TECHNICAL FIELD

[0001] The present disclosure relates to electrospun nanofibrous webs and methods for preparing nanofibrous webs. Particularly, the present disclosure relates to electrospun nanofibrous layers for DNA filtration.

BACKGROUND

[0002] Current methods for DNA separation are focused on isolating total DNA from biological samples that contain nucleic acids, such as whole blood, blood serum, urine, feces, cell cultures, etc. for genomic studies. To this end, first, floating DNAs are degraded by chemical treatments and then genomic DNA is extracted from lysed cells by employing a bind- wash-elute process. Available methods for DNA extraction may include extraction methods that utilize static silica pillars or beads, magnetic silica particles, chitosan-coated surfaces, micro/nanopillar sieves, and nanoporous membranes for DNA separation.

[0003] For example, Tian et al. (Analytical Biochemistry 2000, 283 (2), 175) disclose a solid phase extraction method, in which silica resin is utilized for adsorption and desorption of DNA in a chaitropic salt solution. In other examples, Wolfe et al. (Electrophoresis 2002, 23 (5), 727), Breadmore et al. (Analytical Chemistry 2003, 75 (8), 1880), Cady et al. (Sensors and Actuators B-Chemical 2005, 107 (1), 332), and Wu et al. (Analytical Chemistry 2006, 78 (16), 5704) have disclosed methods in which silica beads, silica particles imobalized in sol-gels, as well as silica-coated pillars have been utilized for purification of DNA. Surface modified magnetic beads have also been used for DNA extraction. For example, Nakagawa et al. (Journal of Biotechnology 2005, 116 (2), 105) disclosed a basic method in which amine surface coating was used for DNA extraction. Amine groups have a positive charge below neutral pH that may cause negatively charged DNA to bind to these amine groups and the charge drops above neutral pH. Cao et al. (Analytical Chemistry 2006, 78 (20), 7222) utilized chitosan surface coating for DNA extraction. Chitosan has a cationic charge and can retain DNA at pH = 5 and is easily neutralized at pH = 9 for DNA releasing. Chitosan have been also coated onto both magnetic beads and microfabricated poly(methyl methacrylate) (PMMA) posts for nucleic acid extraction, as disclosed by Reedy et al. (Lab on a Chip 2011, 11 (9), 1603) and Jiang et al. (Analytical Biochemistry 2012, 420 (1), 20). Kim et al. (Journal of Micromechanics and Microengineering 2006, 16 (1), 33) disclosed a method for DNA extraction. In their method for extracting DNA, a nanoporous aluminum oxide membrane was utilized for DNA filtration. [0004] Most of available techniques for DNA extraction, including the methods and techniques mentioned above, require pH adjustment and utilizing chemical and mostly toxic agents. Consequently, it would be beneficial to provide a method of isolating DNA from a biological sample that does not require pH adjustment or utilizing any chemical and toxic agents. There is further a need for a method for removing floating and free nucleic acids from fluid media by a simple physical filtration method.

SUMMARY

[0005] This summary is intended to provide an overview of the subject matter of the present disclosure and is not intended to identify essential elements or key elements of the subject matter, nor is it intended to be used to determine the scope of the claimed implementations. The proper scope of the present disclosure may be ascertained from the claims set forth below in view of the detailed description and the drawings.

[0006] According to one or more exemplary embodiments, the present disclosure is directed to an active electrospun layer for DNA separation may include a polymer scaffold. An exemplary polymer scaffold may include at least one of aromatic and aliphatic polyester polymers, such as lactic acid / glycolic acid copolymer. An exemplary active electrospun layer for DNA separation may further include an amine-terminated dendritic polymer that may be embedded within the polymer scaffold. An exemplary amine-terminated dendritic polymer may include at least one of polyamidoamine, polypropylene imine, and polyethylene imine. An exemplary active electrospun layer for DNA separation may further include a cationic gemini surfactant.

[0007] In an exemplary embodiment, an exemplary amine-terminated dendritic polymer has a concentration of 5 wt.% to 30 wt.% based on total weight of the polymer scaffold. In an exemplary embodiment, an exemplary cationic gemini surfactant has a concentration of 0.01 wt.% to 0.1 wt.% based on total weight of the polymer scaffold.

[0008] According to one or more exemplary embodiments, the present disclosure is directed to a method for fabricating an active electrospun layer for DNA separation. An exemplary method may include preparing a base polymer solution by dissolving a base polymer in a first solvent, preparing a base polymer/ gemini surfactant solution by mixing a gemini surfactant with the base polymer solution, preparing an amine-terminated dendritic polymer solution by dissolving an amine-terminated dendritic polymer in a second solvent, preparing a spinning solution by dispersing the amine-terminated dendritic polymer solution into the base polymer/ gemini surfactant solution, and preparing the active electrospun layer by electrospinning the spinning solution.

[0009] In an exemplary embodiment, preparing an exemplary base polymer/ gemini surfactant solution may include mixing a first amount of the gemini surfactant with the base polymer solution. The first amount may include between 0.01 wt.% and 0.1 wt.% based on total weight of the base polymer solution.

[0010] In an exemplary embodiment, preparing an exemplary amine-terminated dendritic polymer solution may include dissolving a first amount of the amine-terminated dendritic polymer in the second solvent. The first amount may include between 5 wt.% and 30 wt.% based on total weight of the base polymer.

[0011] In an exemplary embodiment, preparing the base polymer/ gemini surfactant solution may include mixing a first amount of the gemini surfactant with the base polymer solution, an exemplary gemini surfactant may include a cationic gemini surfactant.

[0012] In an exemplary embodiment, preparing the amine-terminated dendritic polymer solution may include dissolving at least one of polyamidoamine, polypropylene imine, and polyethylene imine in the second solvent.

[0013] In an exemplary embodiment, an exemplary first solvent and an exemplary second solvent may be similar. An exemplary first solvent may include at least one of chloroform, dichloromethane, dimethylformamide and an exemplary second solvent may include at least one of dimethylformamide, methanol, ethanol, propanol.

[0014] In an exemplary embodiment, preparing the active electrospun layer may include electrospinning the spinning solution at an electrospinning distance between 15 cm and 20 cm and at a voltage between 20 kV and 25 kV.

[0015] In an exemplary embodiment, preparing an exemplary active electrospun layer may include electrospinning an exemplary spinning solution. The exemplary spinning solution may include 5 to 20 wt.% of the base polymer, 0.01 to 0.1 wt.% of the gemini surfactant, and 5 to 30 wt.% of the dendritic polymer. [0016] According to one or more exemplary embodiments, the present disclosure is directed to a method for DNA filtration. An exemplary method may include preparing an exemplary nanofibrous filter and forcing an exemplary DNA sample through the exemplary nanofibrous filter. An exemplary nanofibrous filter may include a polymer scaffold, where the polymer scaffold may include at least one of aromatic and aliphatic polyester polymers, such as lactic acid / glycolic acid copolymer, an amine -terminated dendritic polymer embedded within the polymer scaffold, where the amine-terminated dendritic polymer may inlcude at least one of polyamidoamine, polypropylene imine, and polyethylene imine, and a cationic gemini surfactant.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The novel features which are believed to be characteristic of the present disclosure, as to its structure, organization, use and method of operation, together with further objectives and advantages thereof, will be better understood from the following drawings in which a presently preferred embodiment of the present disclosure will now be illustrated by way of example. It is expressly understood, however, that the drawings are for the purpose of illustration and description only and are not intended as a definition of the limits of the present disclosure. Embodiments of the present disclosure will now be described by way of example in association with the accompanying drawings in which:

[0018] FIG. 1 illustrates a structural representation of a fourth generation of Polyamidoamine (PAMAM) dendritic polymer, consistent with one or more exemplary embodiments of the present disclosure;

[0019] FIG. 2 illustrates a structure of a cationic gemini surfactant, consistent with one or more exemplary embodiments of the present disclosure;

[0020] FIG. 3 illustrates a flowchart of a method for preparing a positively-charged dendrimer/gemini surfactant membrane, consistent with one or more exemplar embodiments of the present disclosure;

[0021] FIG. 4 illustrates an electrospinning apparatus, consistent with one or more exemplary embodiments of the present disclosure;

[0022] FIG. 5 illustrates Fourier-transform infrared (FTIR) spectra of nanofibrous layers prepared utilizing different spinning solutions, consistent with one or more exemplary embodiments of the present disclosure; [0023] FIG. 6 illustrates a bar chart of water and oil contact angles for nanofibrous layers prepared utilizing different spinning solutions, consistent with one or more exemplary embodiments of the present disclosure;

[0024] FIG. 7 illustrates surface arrangement of gemini surfactants on a PLLA surface, consistent with one or more exemplary embodiments of the present disclosure;

[0025] FIG. 8 illustrates a table reporting DNA separation results, consistent with one or more exemplary embodiments of the present disclosure; and

[0026] FIG. 9 illustrates a schematic representation of an exemplary interaction between an exemplary PLLA/gemini surfactant/PAMAM nanofibrous filter and an exemplary DNA sample, consistent with one or more exemplary embodiments of the present disclosure.

DETAILED DESCRIPTION

[0027] The novel features which are believed to be characteristic of the present disclosure, as to its structure, organization, use and method of operation, together with further objectives and advantages thereof, will be better understood from the following discussion.

[0028] The present disclosure relates to exemplary embodiments of an electrospun nanofibrous article or membrane, a method for fabrication an electrospun nanofibrous membrane, and a method for utilizing an electrospun nanofibrous membrane for removing floating and free nucleic acids, such as antibiotic-resistant DNA from fluid media such as drinking water. An exemplary electrospun nanofibrous membrane may include a positively charged dendrimer/gemini surfactant membrane.

[0029] Dendrimers are artificial macromolecules that are characterized by tree-like topological structures, highly branched structures of great regularity with empty spaces between the branches, compact shapes, and large numbers of reactive end groups. As used herein, an exemplary highly branched structure may refer to a macromolecule structure with a high degree of branching originated from a core region. Examples of highly branched dendritic macromolecules may include, but are not limited to, dendrimers, hyperbranched polymers, dendrigraft polymers, and core- shell dendrimers.

[0030] An exemplary dendrimer may include a core, hyperbranched arms extending from the core with repeated units, and surface functional groups. Exemplary surface functional groups may be located on an outermost layer of an exemplary dendrimer in a multivalent fashion and may significantly influence the physical and chemical properties of the dendrimer. Due to the abundance of hollow spaces between interior branches, an exemplary dendritic structure may host a wide variety of nonpolar or charged guest molecules into its hollow spaces or pockets by hydrophobic/hydrogen-bond interactions. Furthermore, due to the abundance of surface functional groups, an exemplary dendritic structure may host a wide variety of nonpolar or charged guest molecules on its surface by electrostatic interactions.

[0031] FIG. 1 illustrates a structural representation of a fourth generation of Polyamidoamine (PAMAM) dendritic polymer 10, consistent with one or more exemplary embodiments of the present disclosure. In an exemplary embodiment, PAMAM dendritic polymer 10 may include a core region 12 and extended branches 14 originated from core region 12. In an exemplary embodiment, extended branches 14 may be terminated by amie functional groups 16, hence, PAMAM dendritic polymer is an amine-terminated dendritic polymer.

[0032] An exemplary functional group of an exemplary dendrimer, for example amine functional groups 16 of PAMAM dendritic polymer 10 may act as a reactive site, which may be capable of attracting and binding to guest molecules of interest. On the other hand, hollow spaces between exemplary branches of an exemplary dendrimer, for example, hollow spaces between extended branches 14 of PAMAM dendritic polymer 10 may act as cages or spaces in which a guest molecule of interest may be encaged or encapsulated.

[0033] A gemini surfactant may include two monomeric surfactant molecules that may be covalently linked by a spacer. Two polar head groups of the aforementioned monomeric surfactant molecules may be cationic, anionic or nonionic. For example, double quaternary ammonium salts are among cationic gemini surfactant. These polar head groups may determine the classification and properties of surfactants.

[0034] FIG. 2 illustrates a structure of a cationic gemini surfactant 20, consistent with one or more exemplary embodiments of the present disclosure. In an exemplary embodiment, a cationic gemini surfactant, such as cationic gemini surfactant 20 may include at least two hydrophobic chains, such as hydrophobic chains 22 and two hydrophilic quaternary ammonium groups such as hydrophilic quaternary ammonium groups 24 connected by a spacer group, such as spacer 26. In an exemplary embodiment, hydrophobic chains 22 may include linear or branched hydrocarbon chains. Hydrophobic chains 22 may further be functionalized with heteroatoms, such as fluorine, or may contain various functional groups, such as esters, or amide groups. An exemplary spacer group, such as spacer 26 may be hydrophobic, like a polymethylene chain or may be hydrophilic, like polymethylene with ether or hydroxyl groups. From a structural point of view an exemplary spacer group, such as spacer 26 may be rigid, such as an aromatic spacer or may be flexible, like a polymethylene chain. Methyl groups within a cationic gemini surfactant may be substituted with another functional groups, for example, hydroxyethyl or deoxy-D-glucitol. The neutral charge of the surfactant molecule may be retained, by the presence of counterions, which usually are halide anions. The equilibrium between hydrophilic quaternary ammonium groups such as hydrophilic quaternary ammonium groups 24 and hydrophobic parts, such as hydrophobic chains 22 may be responsible for special properties of cationic gemini surfactants in solutions, such as adsorption on the surfaces and interfaces and formation of self-assembly aggregates.

[0035] To get the expected properties of cationic gemini surfactants, the structure must be optimized by modification of HLB of the cationic gemini surfactants. This can be obtained by introduction of balanced polar or hydrophilic functional groups to substituents or to the spacer group. Hydrophilicity may be increased by insertion of hydroxyl, ester, ether, amide etc. groups. To increase lipophilicity, hydrocarbon chains longer than 12 methylene groups, or aromatic rings may be introduced to the substituents or to the spacer group. To increase biodegradability of cationic gemini surfactants, amide, ester or sugar groups may also be introduced to the substituents or to the spacer group.

[0036] The gemini alkylammonium salts show unique interfacial properties in aqueous solution. Critical micelle concentration (CMC) of gemini alkylammonium salts is usually two orders lower than the CMC for corresponding monomeric surfactants. The effectiveness of cationic gemini surfactants in lowering surface tension is also much better than their monomeric counterparts. The values of C20 (surfactant concentration at which the surface tension is lowered by 20 mN/m), are dozen times smaller for gemini surfactants compared to monomeric surfactants. Furthermore, double quaternary ammonium salts may form many morphological structures in solution, like spherical, ellipsoidal, rod shape and worm-like micelles as well as vesicles and helical or tubular forms. This may lead to cationic gemini surfactants to have unique detergent, dispersion and solubilizing properties.

[0037] The gemini alkylammonium compounds further show a very high antimicrobial activity against microorganisms, like Gram positive bacteria, Gram negative bacteria, viruses, molds and yeasts. The mechanism of biocidal activity of quaternary ammonium salts is based on the adsorption of the ammonium cation on the bacterial cell surface, diffusion through the cell wall and then binding and disruption of cytoplasmic membrane. Damage of the membrane results in the release of potassium ions and other cytoplasmatic constituents, leading to the death of the cell. The minimal inhibitory concentrations (MIC) of gemini surfactants against microorganisms are even three orders of magnitude lower in comparison to MIC values of monomeric surfactants. The gemini surfactants may further function as very efficient corrosion inhibitors, due to the presence of two positively charged nitrogen atoms and a large molecular surface.

[0038] Antimicrobial resistance (AMR) continues to be one of the most serious global public health threats. Recently, it has been evidenced that free nucleic acids (NAs) are abundantly present in the effluent of wastewater treatment after bacterial die-off. These free DNAs contain trace amounts of antibiotic resistant DNAs which are often reintroduced to the water supply chains, potentially resulting in the spread of AMR via horizontal gene transfer in the receiving environment. In other words, one plausible cause of “the global resistome” include dispersion of free antibiotic -resistant DNAs in sewage into environments such as soil, fresh water, sea sediments and animals. Antibiotic -resistant DNAs may also be up-taken by human body through drinking water, contaminated food, crops, etc. An exemplary positively charged dendrimer/gemini surfactant membrane may function as an effective barrier for removal of free DNAs including antibiotic -resistant DNAs. An exemplary positively charged dendrimer/gemini surfactant membrane may be utilized as a filter in wastewater and drinking water treatment pipelines. An exemplary positively charged dendrimer/gemini surfactant membrane may prohibit further dispersion of resistant genes into environments and contribute to counteracting the AMR global public health threats.

[0039] Furthermore, since an isoelectric point (Ip) of a virion depends on the amino acid composition of the protein capsid. At pH values above the Ip, viruses have a net negative charge, but below the Ip, their charge is positive. Consequently, at higher pH values, an exemplary positively charged dendrimer/gemini surfactant membrane may adsorb viruses.

[0040] A synergetic effect between amine-terminated dendrimers and cationic gemini surfactants present in the structure of an exemplary positively charged dendrimer/gemini surfactant membrane may be utilized for both virus removal and antibiotic-resistant DNA filtration.

[0041] Exemplary methods and techniques disclosed herein are directed to exemplary embodiments of an exemplary fabrication method for preparing an exemplary positively charged dendrimer/gemini surfactant membrane. An exemplary fabrication method may include preparing an exemplary spinning solution including an exemplary base polymer, an exemplary gemini surfactant, and an exemplary dendritic polymer. An exemplary fabrication method may further include forming an exemplary nanofibrous membrane by electrospinning the exemplary spinning solution. In other words, an exemplary fabrication method may include simultaneous electrospinning of an exemplary base polymer and an exemplary dendritic polymer in the presence of a gemini surfactant. In an exemplary embodiment, such simultaneous electrospinning of an exemplary base polymer and an exemplary dendritic polymer in the presence of a gemini surfactant may allow for the presence of the exemplary gemini surfactant within the exemplary nanofibrous membrane. The synergetic effect between amine-terminated dendrimers and cationic gemini surfactants present in the structure of an exemplary positively charged dendrimer/gemini surfactant membrane may make the exemplary positively charged dendrimer/gemini surfactant membrane an effective filter for both virus removal and antibiotic -resistant DNA filtration.

[0042] FIG. 3 illustrates a flowchart of a method 30 for preparing a positively-charged dendrimer/gemini surfactant membrane, consistent with one or more exemplar embodiments of the present disclosure. In an exemplary embodiment, method 30 may include a step 32 of preparing a polymer solution by dissolving a base polymer in a first solvent, a step 34 of preparing a polymer/surfactant solution by mixing a gemini surfactant with the polymer solution, a step 36 of preparing an amine-terminated dendritic polymer solution by dissolving an amine-terminated dendritic polymer in a second solvent, a step 38 of preparing a spinning solution by dispersing the amine-terminated dendritic polymer solution into the polymer/surfactant solution, and a step 310 of preparing the positively-charged dendrimer/gemini surfactant membrane by electrospinning the spinning solution to obtain the scented nanofibrous layer.

[0043] In an exemplary embodiment, step 32 may include preparing the polymer solution by dissolving a base polymer such as aromatic and aliphatic polyester polymers, such as lactic acid / glycolic acid copolymer, or combinations thereof in a suitable first solvent for the first polymer, where the first solvent may be one of chloroform, dichloromethane, dimethylformamide, and mixtures thereof. In an exemplary embodiment, the polymer solution may have a polymer-to-solvent concentration between 5 (w/v) % and 20 (w/v) %.

[0044] In an exemplary embodiment, step 34 of preparing the polymer/surfactant solution may include mixing a gemini surfactant, such as hexamethylene- l,6-bis(N,N-dimethyl-N- dodecylammonium bromide), 3 -oxapentylene -l,5-bis(N,N-dimethyl-N-dodecylammonium bromide), 3 -azapentylene -l,5-bis(N,N-dimethyl-N-dodecylammonium bromide), or combinations thereof with the polymer solution. In an exemplary embodiment, the gemini surfactant may have a concentration between 0.01 (w/v) % and 0.1 (w/v) % based on the total volume of the polymer solution. In an exemplary embodiment, mixing a gemini surfactant with the polymer solution may aid in emulsifying an exemplary mixture of an exemplary polymer solution and an exemplary dendritic polymer solution that may be mixed with the exemplary polymer solution in the following steps. In an exemplary embodiment, mixing a gemini surfactant with the polymer solution may further enhance the virus removal and DNA filtration capabilities of an exemplary positively-charged dendrimer/gemini surfactant membrane.

[0045] In an exemplary embodiment, step 36 of preparing the amine-terminated dendritic polymer solution may include dissolving the amine-terminated dendritic polymer in the second solvent in an amount such that the amine-terminated dendritic polymer may have a concentration between 5 wt. % and 30 wt. % based on the weight of the first polymer. In an exemplary embodiment, dissolving the amine-terminated dendritic polymer in the second solvent may include adding the amine-terminated dendritic polymer to the second solvent while being stirred by a stirrer such as a mechanical stirrer, a sonicator, or other similar homogenizers. In an exemplary embodiment, dissolving the amine-terminated dendritic polymer in the second solvent may include adding the amine-terminated dendritic polymer to at least one of dimethylformamide, methanol, ethanol, propanol, and mixtures thereof. In an exemplary embodiment, dissolving the amine-terminated dendritic polymer in the second solvent may include adding at least one of a hyperbranched polymer, a dendrigraft polymer, a dendrimer, or mixtures thereof in the second solvent. In an exemplary embodiment, the first solvent and the second solvent may be similar.

[0046] In an exemplary embodiment, step 38 may include preparing the spinning solution by dispersing the amine-terminated dendritic polymer solution into the polymer/surfactant solution, such that the spinning solution may include the base polymer with a concentration between 5 (w/v) % and 20 (w/v) % in the first solvent, the gemini surfactant with a concentration between 0.01 wt. % and 0.1 wt. % based on the weight of the first polymer, and the amine-terminated dendritic polymer with a concentration between 5 wt. % and 30 wt. % based on the weight of the first polymer. [0047] In an exemplary embodiment, step 310 may include electrospinning the spinning solution in an electrospinning apparatus to obtain the positively-charged dendrimer/gemini surfactant membrane. In an exemplary embodiment, the electrospinning may be carried out with different flow rates at different spray-to-collector distances. For example, electrospinning the spinning solution may be carried out at a nozzle-to-collector distance between 15 cm and 20 cm at a voltage between 20 kV and 25 kV, and with a flow rate of between 0.5 cm ³ hr ^-1 and 1 cm ³ hr ^-1 . In an exemplary embodiment, step 312 may include electrospinning the spinning solution in a needleless electrospinning apparatus to obtain the positively-charged dendrimer/gemini surfactant membrane.

[0048] FIG. 4 illustrates an electrospinning apparatus 40, consistent with one or more exemplary embodiments of the present disclosure. In an exemplary embodiment, apparatus 40 may include an electrospinning nozzle 42 that may be utilized for injecting an exemplary spinning solution and a collector 44 placed in front of nozzle 42 at a distance 48. In an exemplary embodiment, distance 48 may be adjustable. A power supply system 410 connected to both nozzle 42 and collector 44 may apply a predetermined potential difference between a tip 46 of nozzle 42 and collector 44. In an exemplary embodiment, collector 44 may be grounded.

[0049] In an exemplary embodiment, step 310 of preparing the positively-charged dendrimer/gemini surfactant membrane may include electrospinning of the spinning solution onto a collector, such as collector 44 from an electrospinning nozzle such as nozzle 42 with a flow rate between 0.5 cm ³ hr ^-1 and 1 cm ³ hr ^-1 . Collector 44 may be positioned at distance 44. In an exemplary embodiment, distance 48 may be between 15 cm and 20 cm from tip 46 of electrospinning nozzle 42. A power supply system such as power supply system 410 may apply a voltage between 20 kV and 25 kV between nozzle tip 46 and collector 44.

EXAMPLE 1

[0050] In this example, a nanofibrous layer of poly(L-Lactic acid) (PLLA)/gemini surfactant/polyamidoamine (PAMAM) was prepared utilizing a synthesis method similar to method 30 of FIG. 3. First, PLLA as the base polymer was dissolved in a solvent system containing chloroform (CHCI3) and N,N-dimethylformide (DMF) with a CHCI3: DMF ratio of 85:15 v/v. Then, a PLLA/gemini surfactant solution was prepared by mixing a gemini surfactant with the PLLA solution. A second generation PAMAM solution was prepared by dissolving a second generation PAMAM polymer in a solvent system containing chloroform (CHCI3) and N,N-dimethylformide (DMF) with a CHCI3: DMF ratio of 85:15 v/v. After that, a spinning solution was prepared by dispersing the second generation PAMAM solution into PLLA/gemini surfactant solution. The spinning solution included 10 wt.% of PLLA, 0.01 wt.% of the gemini surfactant, and 10 wt.% of the second generation PAMAM polymer based on the total weight of the spinning solution.

[0051] The prepared spinning solution was electrospun in an electrospinning system with a feeding rate of approximately 0.5 ml/h, an electrospinning distance of approximately 18 cm, and a voltage of approximately 20 kV. The electrospinning process was carried out at 18-20 °C utilizing an electrospinning nozzle with an inner diameter of 0.4 mm and a cylindrical collector rotating at 2000 rpm. For purpose of comparison, three other samples were prepared under similar electrospinning conditions as described above. A first sample was prepared using a spinning solution containing only a 10 wt.% polymer solution of PLLA in a solvent system containing chloroform (CHCI3) and N,N-dimethylformide (DMF) with a CHCI3: DMF ratio of 85:15 v/v, and second sample was prepared using a spinning solution including a PLLA/gemini surfactant solution containing 10 wt.% of PLLA and 0.01 wt.% of the gemini surfactant. A third sample was prepared using a spinning solution including PLLA with a concentration of 10 wt.% and a second generation PAMAM polymer with a concentration of 10 wt.% based on the total weight of the spinning solution. The first sample is referred to herein as PLLA sample, the second sample is referred to herein as PLLA/gemini surfactant sample, and the third sample is referred to herein as PLLA/PAMAM sample.

[0052] FIG. 5 illustrates Fourier-transform infrared (FTIR) spectra 50 of nanofibrous layers prepared utilizing different spinning solutions, consistent with one or more exemplary embodiments of the present disclosure. FTIR spectra 50 of nanofibrous layers include an FTIR spectrum 52 of PLLA sample, an FTIR spectrum 54 of PLLA/gemini surfactant sample, an FTIR spectrum 56 of PLLA/PAMAM sample, and an FTIR spectrum 58 of PLLA/gemini surfactant/PAMAM sample. Peak band assignments of PLLA are -CH- stretch (2995, 2944) cm ¹ , -C=O- carbonyl (1759 cm ¹ ), -CH- deformation (1362, 1382, 1453) cm ¹ -C-O- stretch (1268, 1194, 1130 ,1093 1047) cm ¹ and -C-C- stretch (868 cm ¹ ). Utilizing a dendritic polymer, and a gemini surfactant in the spinning solution, may cause a cleavage in the ester bond of PLLA. During the interaction, nucleophilic attacks were done and new functional groups were formed after cleaving the ester bonds. Referring to FIG. 5, a decrease is evident in the intensity of the 1750 cm ¹ peak and the presence of wide peaks within the range of 2800-3650 cm ¹ attributed to C=O and -COOH vibrations, respectively.

[0053] FIG. 6 illustrates a bar chart 60 of water and oil contact angles for nanofibrous layers prepared utilizing different spinning solutions, consistent with one or more exemplary embodiments of the present disclosure. Bar chart 60 includes water contact angle bar 62a and oil contact angle bar 62b for PLLA/PAMAM sample, water contact angle bar 64a and oil contact angle bar 64b for PLLA sample, water contact angle bar 66a and oil contact angle bar 66b for PLLA/gemini surfactant/PAMAM sample, and water contact angle bar 68a and oil contact angle bar 68b for PLLA/gemini surfactant sample. It is evident that, PLLA/PAMAM sample shows the highest wettability due to the presence of amin functional end groups within the structure of the PLLA/PAMAM sample. It is further evident that, PLLA/gemini surfactant sample has the lowest wettability due to the long hydrophobic tail and surface arrangement of the gemini surfactant.

[0054] FIG. 7 illustrates surface arrangement of gemini surfactants 70 on PLLA surface 72, consistent with one or more exemplary embodiments of the present disclosure. PLLA surface 72 has a negative charge, therefore, when PLLA is exposed to gemini surfactants 70, gemini surfactants 70 may tend to turn form the positive heads of gemini surfactants 70 towards PLLA surface 72. In such arrangement of gemini surfactants 70, since hydrophobic tails are positioned outward, the wettability of the sample decreases.

EXAMPLE 2

In this example, synthesized nanofibrous layers of PLLA /gemini surfactant/PAMAM were utilized in a spin filter of a DNA capturing kit. To this end and for the purpose of comparison, PLLA /gemini surfactant/PAMAM nanofibrous filter, PLLA nanofibrous filter, PLLA/gemini surfactant nanofibrous filter, and PLLA/PAMAM nanofibrous filter as-synthesized in Example 1, referred to hereinafter as nanofibrous filters, were placed in a number of spin filter tubes. Each spin filter tube was centrifuged at 13500 rpm for 30 seconds to make sure that each nanofibrous filter was properly disposed within each respective spin filter tube. After that, 2 pl of a DNA sample with a concentration of 600 ng/mL was pipetted on top of each nanofibrous filter. In this example, DNA sample was extracted from soil and encompasses a community of microorganisms. Spin filters were then placed in falcon tubes and were centrifuged at 12500 rpm for 2 min. Then, the filtrate from each spin filter was used to measure the DNA concentration. [0055] FIG. 8 illustrates a table 80 reporting DNA separation results, consistent with one or more exemplary embodiments of the present disclosure. As discussed in the preceding paragraph, four different DNA separation set-ups were utilized for evaluating the performances of the nanofibrous filters synthesized in Example 1. The DNA separation set-up, in which, a PLLA nanofibrous filter was utilized within the spin filter of the DNA separation kit is referred to as set-up “B” in table 80. The DNA separation set-up, in which, a PLLA/gemini surfactant nanofibrous filter was utilized within the spin filter of the DNA separation kit is referred to as set-up “C” in table 80. The DNA separation set-up, in which, a PLLA/PAMAM nanofibrous filter was utilized within the spin filter of the DNA separation kit is referred to as set-up “D” in table 80. The DNA separation set-up, in which, a PLLA/gemini surfactant/PAMAM nanofibrous filter was utilized within the spin filter of the DNA separation kit is referred to as set-up “E” in table 80.

[0056] Referring to FIG. 8, maximum amount of DNA filtration was achieved with set-up “E”, where a PLLA/gemini surfactant/PAMAM nanofibrous filter was utilized within the spin filter of the DNA separation kit. Not bound by any particular theory, this may be due to an increase in surface charge, which in turn may be due to the positive surface charge of the gemini surfactant and the dendrimer.

[0057] FIG. 9 illustrates a schematic representation of an exemplary interaction between an exemplary PLLA/gemini surfactant/PAMAM nanofibrous filter and an exemplary DNA sample, consistent with one or more exemplary embodiments of the present disclosure. In an exemplary embodiment, interactions among PAMAM dendritic polymer 92, gemini surfactant 94, PLLA 96, and DNA sample 98 is illustrated in this figure. It may be evident that in an exemplary PLLA/gemini surfactant/PAMAM nanofibrous filter, an exemplary gemini surfactant is not only functioning as a surfactant, but the synergetic effect of simultaneous presence of an exemplary gemini surfactant and an exemplary amine terminated dendrimer may allow for an efficient DNA removal.

[0058] While the foregoing has described what are considered to be the best mode and/or other examples, it is understood that various modifications may be made therein and that the subject matter disclosed herein may be implemented in various forms and examples, and that the teachings may be applied in numerous applications, only some of which have been described herein. It is intended by the following claims to claim any and all applications, modifications and variations that fall within the true scope of the present teachings. [0059] Unless otherwise stated, all measurements, values, ratings, positions, magnitudes, sizes, and other specifications that are set forth in this specification, including in the claims that follow, are approximate, not exact. They are intended to have a reasonable range that is consistent with the functions to which they relate and with what is customary in the art to which they pertain.

[0060] The scope of protection is limited solely by the claims that now follow. That scope is intended and should be interpreted to be as broad as is consistent with the ordinary meaning of the language that is used in the claims when interpreted in light of this specification and the prosecution history that follows and to encompass all structural and functional equivalents. Notwithstanding, none of the claims are intended to embrace subject matter that fails to satisfy the requirement of Sections 101, 102, or 103 of the Patent Act, nor should they be interpreted in such a way. Any unintended embracement of such subject matter is hereby disclaimed.

[0061] Except as stated immediately above, nothing that has been stated or illustrated is intended or should be interpreted to cause a dedication of any component, step, feature, object, benefit, advantage, or equivalent to the public, regardless of whether it is or is not recited in the claims.

[0062] It will be understood that the terms and expressions used herein have the ordinary meaning as is accorded to such terms and expressions with respect to their corresponding respective areas of inquiry and study except where specific meanings have otherwise been set forth herein. Relational terms such as first and second and the like may be used solely to distinguish one entity or action from another without necessarily requiring or implying any actual such relationship or order between such entities or actions. The terms “comprises,” “comprising,” or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element proceeded by “a” or “an” does not, without further constraints, preclude the existence of additional identical elements in the process, method, article, or apparatus that comprises the element.

[0063] The Abstract of the Disclosure is provided to allow the reader to quickly ascertain the nature of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. In addition, in the foregoing Detailed Description, it can be seen that various features are grouped together in various implementations. This is for purposes of streamlining the disclosure and is not to be interpreted as reflecting an intention that the claimed implementations require more features than are expressly recited in each claim. Rather, as the following claims reflect, the inventive subject matter lies in less than all features of a single disclosed implementation. Thus, the following claims are hereby incorporated into the Detailed Description, with each claim standing on its own as a separately claimed subject matter.

[0064] While various implementations have been described, the description is intended to be exemplary, rather than limiting and it will be apparent to those of ordinary skill in the art that many more implementations and implementations are possible that are within the scope of the implementations. Although many possible combinations of features are shown in the accompanying figures and discussed in this detailed description, many other combinations of the disclosed features are possible. Any feature of any implementation may be used in combination with or substituted for any other feature or element in any other implementation unless specifically restricted. Therefore, it will be understood that any of the features shown and/or discussed in the present disclosure may be implemented together in any suitable combination. Accordingly, the implementations are not to be restricted except in light of the attached claims and their equivalents. Also, various modifications and changes may be made within the scope of the attached claims.

[0065] The embodiments have been described above with the aid of functional building blocks illustrating the implementation of specified functions and relationships thereof. The boundaries of these functional building blocks have been arbitrarily defined herein for the convenience of the description. Alternate boundaries can be defined so long as the specified functions and relationships thereof are appropriately performed.

[0066] The foregoing description of the specific embodiments will so fully reveal the general nature of the disclosure that others can, by applying knowledge within the skill of the art, readily modify and/or adapt for various applications such specific embodiments, without undue experimentation, without departing from the general concept of the present disclosure. Therefore, such adaptations and modifications are intended to be within the meaning and range of equivalents of the disclosed embodiments, based on the teaching and guidance presented herein. It is to be understood that the phraseology or terminology herein is for the purpose of description and not of limitation, such that the terminology or phraseology of the present specification is to be interpreted by the skilled artisan in light of the teachings and guidance.

[0067] The breadth and scope of the present disclosure should not be limited by any of the above-described exemplary embodiments but should be defined only in accordance with the following claims and their equivalents.

[0068] Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not to the exclusion of any other integer or step or group of integers or steps. [0069] Moreover, the word "substantially" when used with an adjective or adverb is intended to enhance the scope of the particular characteristic; e.g., substantially planar is intended to mean planar, nearly planar and/or exhibiting characteristics associated with a planar element. Further use of relative terms such as “vertical”, “horizontal”, “up”, “down”, and “side-to-side” are used in a relative sense to the normal orientation of the apparatus.