Essay Example on Research on Polymer Nanofibers and their Applications








Research on polymer nanofibers and their applications has seen a remarkable growth over the last few years 1 8 This is due to larger surface areas per unit mass and permit easier addition of surface functionalities compared with polymer microfibers Hence polymer nanofiber mats are used as scaffolds for tissue engineering 9 protective clothing drug delivery applications 10 and antimicrobial applications 11 Electrospinning is a powerful technique for the continuous production of polymeric fibers Fibers can be electrospun from solutions or melts and processing conditions can be adjusted to control fiber diameter 12 14 Bacterial infections have become a serious problem in areas such as medical devices healthcare products water purification systems hospitals dental office equipment food packaging food storage household sanitation 15 18 Hence there is an urgent need to develop strong economically viable and ecofriendly replacements of conventional disinfectants 19 Antimicrobial polymers consider a very convenient way for achieving this goal The use of antimicrobial polymers is promising for enhancing the efficacy of some existing antimicrobial agents and minimizing the environmental problems accompanying conventional antimicrobial agents by reducing the residual toxicity of the agents increasing their efficiency and selectivity and prolonging their lifetime

Also an advantage of polymeric antimicrobial agents is that they are non volatile chemically stable and do not permeate through skin Therefore they can reduce losses associated with volatilization photolytic decomposition and transportation 20 Pluronic F68 also termed Poloxamer is a nonionic triblock copolymer of poly ethylene oxide EO and poly propylene oxide PO blocks arranged in a structure EO PO EO This arrangement results in an amphiphilic copolymer in which the number of hydrophilic EO and hydrophobic PO units can be altered to vary the size hydrophilicity and lipophilicity It is used as an emulsifying agent antifoaming agents solubilizing agent surfactant and wetting agent for antibiotics 21 22 Poloxamers are non toxic and non irritant and so it is also used as wetting agents in ointments suppository bases and gels 23 24 The nanofibers produced from electrospinning of pluronic F68 were used in various applications such as skin tissue engineering wound dressing drug delivery system and antimicrobial activity 25 29 In this study pluronic F68 was modified with chloroacetyl chloride followed by immobilization of onium groups onto the chloroacetylated polymer Then the ammonium and phosphonium salts of pluronic were electrospun in the presence of cellulose acetate as cospinning agent Antibacterial activities of the modified polymer and the electrospun nanofibers were explored in vitro against gram negative and gram positive bacteria by diffusion method Blended Polymer solutions were prepared with fixed concentration of 20 wt by dissolving the mixture of pluronic F68 and cellulose acetate in acetone DMF at different ratios 100 0 75 25 50 50 and 25 75 The solutions were stirred at room temperature for 30 min until a homogeneous solution was obtained The solutions of polymer blend were pumped through a syringe with a 22 gauge needle at rates of 0 7 1 mL h

The distance from the end of the needle to the collector plate was fixed at 7 cm The voltage was varied from 19 to 23 kV until a stable Taylor cone was achieved The electrospun fibers were collected on cleaned aluminum foil All nanofibers were made at room temperature and relative humidity 40 55 The obtained nanofibers were characterized by SEM 2 5 Antimicrobial Activities of the Modified Pluronic F68 and Pluronic blend Nanofibers 2 5 1 Tested Microorganisms The test microorganisms included were Gram negative bacteria Escherichia coli Proteus vulgaris Klebsiella pneumoniae and the Gram positive bacteria Staphylococcus aureus The test microorganisms were obtained from Microbiology section Botany Department Faculty of Science Tanta University Egypt The bacterial strains were maintained on nutrient agar which contained 3 g peptone 5 g NaCl 5 g beef extract 20 g agar per liter 2 5 2 Screening of the antimicrobial activity for Pluronic and electrospun pluronic blend nanofibers The antimicrobial activitiy of the tested samples were determined by well diffusion method To perform the test several colonies of each strain Escherichia coli Proteus vulgaris Klebsiella pneumonia and Staphylococcus aureus obtained from a fresh culture in blood agar plate were suspended in 5 ml of Mueller Hinton broth to achieve turbidity equal to 107 colony forming unit CFU The suspensions were inoculated with sterile swabs onto 150 mm diameter Mueller Hinton agar plates and after the agar surfaces were allowed to dry Powder test samples 20 mg mL were dissolved in DMSO In case of nanofibers the antimicrobial activitiy of pluronic in pluronic cellulose acetate fibers was tested by agar plate diffusion method The circular foil sample and nanofibers disks were placed on each plate Plates were incubated at 37 o C for 24 hour and the zones of inhibition were measured

Aluminum foil was used as a control Among the polymeric materials cationic polymers containing quaternary ammonium groups have proven to be effective antimicrobials and biocides 23 Quaternization of the chloroacetylated polymer were carried out in dry benzene by reacting chloroacetylated pluronic II either with triethyl amine TEA or triphenyl phosphine TPP or tributyl phosphine TBP at room temperature followed by heating at 80 oC for 4 days Scheme 2 The nitrogen content of the polymers III V were determined by elemental microanalysis which were in good agreement with the calculated values as shown in table 1 The IR spectrum of the polymers III V indicated the presence of peaks at 1476 1911 and 2975 cm 1 for quaternary ammonium salt 1494 1402 cm 1 for P Ph and 1477 cm 1 for P CH2 as shown in Figure 1 The 1H NMR spectrum of the quaternized polymers show characteristic bands at 1 12 and 3 07 ppm belongs to proton of triethyl amine multiplet band at 7 8 ppm indicates presence of phenyl groups of triphenyl phosphine and bands at 0 9 and 1 2 1 4 ppm which belongs to protons of tributyl phosphine

Write and Proofread Your Essay
With Noplag Writing Assistance App

Plagiarism Checker

Spell Checker

Virtual Writing Assistant

Grammar Checker

Citation Assistance

Smart Online Editor

Start Writing Now

Start Writing like a PRO