Antimicrobial properties of chitosan nanoparticles: Mode of action and factors affecting activity

The present investigation describes the synthesis and characterization of novel biodegradable nanoparticles based on chitosan for biomedical applications. The presence of primary amine groups in repeating units of chitosan grants it several properties like antibacterial activity, antitumor activity and so on. Chitosan forms nanoparticles spontaneously on the addition of polyanion tripolyphosphate which has greater antimicrobial activity than parent chitosan. In the present study, chitosan nanoparticles (ChNP) were prepared by the ionic gelation method. The physiochemical characteristics of nanoparticles were analyzed using XRD, SEM, FTIR. The antibacterial activity of chitosan nanoparticles against medical pathogens Klebsiella pneumoniae, Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa was evaluated by calculation of minimum inhibitory concentration (MIC) and compared with chitosan and chitin activity. The mode of action and factors affecting antibacterial activity were also analyzed. ChNP compounds exhibited superior antimicrobial activity against all microorganisms in comparison with chitosan and chitin. The antibiofilm activity was studied using crystal violet assay and growth on congo red agar. The study is thus a good demonstration of the applicability of chitosan nanoparticles as an effective antimicrobial agent with antibiofilm activity as well.     

Preparation of Porous <Emphasis Type="Italic">m</Emphasis>-aramid/cellulose Blend Membranes with High Moisture and Air Permeability by an Enzymatic Degradation Method

Enzyme degradation method was adopted to prepare porous m-aramid/cellulose blend membranes with high air permeability, water absorbency and moisture permeability. This facile preparation process started by casting a blend membrane from a DMAc/LiCl solution containing m-aramid and cellulose. An enzyme was then used to degrade the cellulose in the blend membrane, resulting in porous structures. Five enzymes including cellulase, chitosanase, papain, lipase, and glucose oxidase, were evaluated and cellulase was found to be optimal. Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) were used to characterize the miscibility and the morphology of the m-aramid/cellulose blend membranes before and after degradation, respectively. The thermal stability of the blend membranes were characterized by thermogravimetric analysis (TGA). The properties including air permeability, water absorbency and moisture permeability of the m-aramid/cellulose blend membranes greatly improved after degradation as compared to those of the pure m-aramid. This paper provided a new approach to preparing novel textile materials with high comfortability.     

Durable antibacterial cotton fabrics with chitosan based quaternary ammonium salt

A water soluble quaternary ammonium chitosan derivative, N-benzyl-N,N-diethyl chitosan quaternary ammonium salt (BDCQA), was prepared for antibacterial finish of cotton textiles. The effects of concentrations of finish agents and treatment time on the add-on ratio of cotton treated BDCQA (BDCQA-cotton) were studied in details. The morphology and thermal property of BDCQA-cotton were characterized by scanning electron microscopy (SEM) and thermagravimetric (TG) analysis. Gram-positive bacterium Staphylococcus aureus (S. aureus) and Bacillus cereus (B. cereus), Gram-negative bacterium Escherichia coli (E. coli) and drug-resistant bacterium Methicillin-resistant Staphylococcus aureus (MRSA), were used to evaluate the antibacterial activity and durability of BDCQA-cotton. The results showed that BDCQA-cotton possessed good antibacterial activity and high durability against broad spectrum bacterium. The preliminary investigation on the antibacterial mechanism was discussed in this work.     

Rheological behavior and spinnability of ethylamine hydroxyethyl chitosan/cellulose co-solution in N-methylmorpholine-N-oxide system

In this work, the novel chitosan derivative ethylamine hydroxyethyl chitosan (EHC) was synthesized and blended with cellulose in an aqueous N-methylmorpholine-N-oxide (NMMO) solution in order to fabricate antibacterial chitosan/cellulose fiber. The rheological behaviors of the obtained co-solution in both steady and dynamic states were carefully investigated to determine the spinnability of the co-solution. In steady state, the addition of EHC was found to preserve the power-law flow characteristics of cellulose in the aqueous NMMO solution, while broadening the first Newtonian fluid-flow area. Under dynamic conditions, both Han-plot and viscoelastic analyses indicated the homogeneity of the co-solution. EHC/cellulose antibacterial fibers were successfully spun via the lyocell process using aqueous NMMO as the solvent, confirming the excellent spinnability of the EHC/cellulose co-solution. Scanning electron microscopy was used to observe the morphology of the obtained EHC/cellulose fibers; they were also investigated for antibacterial activity. The obtained EHC/cellulose fiber exhibited good spinning consistency and strong antibacterial activity against Escherichia coli, demonstrating potential applications for the material in antibacterial textiles.     

Preparation of chitosan fibers using aqueous ionic liquid as the solvent

In this work, acidic ionic liquid glycine hydrochloride (Gly·HCl) is reported as a new solvent for dissolving chitosan. The regenerated chitosan fibers were fabricated by a wet spinning process and characterized by scanning electronic microscopy, fourier transform infrared spectroscopy, wide-angle X-ray diffraction and thermal gravimetric analysis. The result shows that the regenerated chitosan fibers had the same chemical structure as the raw chitosan flake, however, its thermal stability and crystallinity is a little low. Furthermore, a new mechanism of dissolving chitosan in ionic liquid was proposed. The chitosan fibers had soft feeling, excellent antibacterial property and have huge potential application in biomaterials.     

Leveraging the Antibacterial Properties of Knitted Fabrics by Admixture of Polyester-Silver Nanocomposite Fibres

Leveraging the antibacterial properties of polyester-cotton knitted fabrics has been attempted in this research by admixture of small proportion of polyester-silver nanocomposite fibres. Polyester-cotton (50:50) yarns were spun by mixing 10, 20 and 30 % (wt.%) polyester-silver nanocomposite fibres with normal polyester fibres so that overall proportion of polyester fibre becomes 50 %. The proportion of cotton fibre was constant (50 %) in all the yarns. Three parameters, namely blend proportion (wt.%) of nanocomposite fibres, yarn count and knitting machine gauge were varied, each at three levels, for producing 27 knitted fabrics. Polyester-cotton knitted fabrics prepared from polyester-silver nanocomposite fibres showed equally good antibacterial activity (65-99 %) against both S. aureus and E. coli bacteria. Antibacterial properties were enhanced with the increase in the proportion of polyester-silver nanocomposite fibres, yarn coarseness and increased compactness of knitted fabrics. Yarn count and blend proportion of nanocomposite fibre were found to have very dominant influence in determining the antibacterial properties of knitted fabrics.     

Synthesis of non-water soluble polymeric guanidine derivatives and application in preparation of antimicrobial regenerated cellulose

In order to prepare antimicrobial regenerated cellulose fibers from blended spinning solutions, three non-water soluble polymeric guanidine derivatives, polyhexamethylene guanidine dodecyl benzene sulfonate (PHGDBS), polyhexamethylene guanidine dodecyl sulfate (PHGDSA), and polyhexamethylene guanidine laurylsulfonate (PHGLSO) were synthesized. And the chemical structure of these agents was verified by element analysis, Fourier transform infrared spectroscopy (FTIR), and proton nuclear magnetic resonance (¹H-NMR). The antimicrobial activity of the three agents as well as cellulose films containing PHGDBS was also studied. The results showed that the compounds we prepared had strong properties against both bacterial and fungus, including Staphylococcus aureus (S. aureus), Escherichia coli (E. coli), Candida albicans, and Aspergillus niger. Moreover, it was found that three antimicrobial agents were insoluble in water but they can dissolve in solvents of cellulose such as 1-butyl-3-methylimidazolium chloride ([BMIM]Cl) and N-methylmorpholine-N-oxide monohydrate (NMMO·H₂O). Meanwhile, it was also proved that [BMIM]Cl had little effect on the antimicrobial properties of these agents. The cellulose films containing only 1.0 wt% PHGDBS showed 99.94 % and 96.95 % bacterial reduction rates for S. aureus and E. coli, respectively. Moreover, still over 91 % of bacterial reduction was maintained after 15 laundering cycles. It suggests that the three agents will be suitable to prepare antimicrobial regenerated cellulose fibers or films.     

One Step Thermochromic Pigment Printing and Ag NPs Antibacterial Functional Finishing of Cotton and Cotton/PET Fabrics

One step thermochromic pigment printing and antibacterial functionality of cotton (100 %) and cotton/polyester blend (50/50 %) were demonstrated in this study. The improvement in antimicrobial activity against G+ve (Bacillus cereus) and G-ve (E. coli), and pigment printability were achieved by inclusion of Ag-NPs (30 g/kg) into pigment printing paste followed by printing and microwave curing at 700 W for 5 min. Modes of interactions were proposed, and surface modification was also confirmed by SEM and EDX analysis that proved the presence of Ag-NPs in cotton and cotton/ polyester blended samples. The results indicated that the colour fastness to wash and rubbing was excellent, the surface roughness reduced, and exhibited good antibacterial activity against Bacillus cereus and E. coli bacteria.     

Influence of residual ionic liquid on the thermal stability and electromechanical behavior of cellulose regenerated from 1-ethyl-3-methylimidazolium acetate

The regenerated cellulose films were prepared by dissolving cotton cellulose pulp directly in room temperature ionic liquid namely, 1-ethyl-3-methylimidazolium acetate at 80 °C, followed by washing/curing in different coagulants namely, methanol, deionized water, methanol-deionized water, and isopropyl alcohol-deionized water. It was found that the type of coagulants employed for curing the cellulose films has a significant influence on the amount of residual ionic liquid entrapped in the films. The amount of residual ionic liquids was 2.68, 1.01, 0.84, and 0.75 wt.% for the films cured with deionized water, isopropyl alcohol-deionized water, methanol, and methanol-deionized water, respectively. The DTG peaks of regenerated cellulose films showed two decomposition temperatures at 280 °C and 320 °C. Among all the cases studied, deionized water curing case showed the lowest decomposition temperature, attributed to entrapment of large residual ionic liquid in it. Electromechanical characteristic of the regenerated cellulose films was also investigated.     

Study on antibacterial and comfort performances of cotton fabric finished by chitosan-silver for intimate apparel

The fabric used for intimate apparel is widely required to have excellent antibacterial and comfort performances. In order to improve its antibacterial ability, this paper studied chitosan-silver finishing on the cotton knitted fabric. The study indicates that the chitosan-silver attached to the fabric exhibits excellent antibacterial action against the typical bacteria of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureu). The anti-bacterial mechanism of chitosan-silver against E. coli and S. aureu were investigated. To guarantee its prominent comfort performance, measurements were made on the finished fabric of its air permeability, water vapor transmission, hydrophily, surface friction and bending ability against the control fabric, which is currently used for intimate apparel. The antibacterial and comfort performances were compared between the tested fabrics. The results show that the air permeability and the hydrophily of the finished cotton fabric are significantly better than the control one, while the water vapor transmission, the surface friction and the adjustable rate remain similar to each other. The bending rigidity of the finished fabric is slightly better due to the attachment of chitosan within accepted threshold. The dual compounding theory of chitosan-silver proves to be useful for a higher synergistic effect of anti-bacteria, lower whiteness degradation and overall optimization of comfort performance. This dual compounding theory of chitosan-silver is valuable for improving antibacterial and comfort performances of intimate apparel.     

Antibacterial Bombyx Mori silk fabric modified with reactive chitosan quaternary ammonium salt and its laundering durability

A new fiber-reactive chitosan derivative was synthesized in two steps from a chitosan of low molecular weight. First, a water-soluble chitosan derivative, N-[(2-hydroxy-3-trimethylammonium)propyl] chitosan chloride (short for HTCC), was prepared by reacting chitosan with 2,3-epoxypropyltrimethylammonium chloride. Second, HTCC was further modified by reacting with N-(hydroxymethyl)-acrylamide to prepare a fiber-reactive chitosan derivative, O-methyl acrylamide quaternary ammonium salt of chitosan (short for NMA-HTCC), which can form covalent bonds with silk fiber under alkaline conditions. The chemical structure of NMA-HTCC was characterized by Fourier transform infrared spectrum (FTIR) and nuclear magnetic resonance (NMR). The substitution degree of HTCC and the double-bond content of NMA-HTCC were tested. Then NMA-HTCC was used for antibacterial finishing of Bombyx Mori silk fabric. The results showed that silk fabric treated with NMA-HTCC had a significantly improved antibacterial activity to Staphylococcus aureus and Escherichia coli, and the antibacterial activity of silk fabric finished by NMA-HTCC was much better than that finished by chitosan and HTCC. Bombyx Mori silk fabric modified with NMA-HTCC demonstrated excellent durable antibacterial activity, even after 50 repeated launderings, the bacterial reduction rate of silk fabric maintained over 95 %.     

Antimicrobial and cellular activity of poly(L-lactide)/chitosan/Imipenem antibiotic composite nanofibers

Synthesis of biocompatible polymer nanofibers is valuable, due to their use as a cover for burns and as a replacement for bandage because of their antimicrobial properties. In this study, electrospinning of chitosan(Ch) and nanofibers synthesis with antibacterial properties was investigated. Nanofibers with antibacterial properties were synthesized by electrospun of Ch/poly(L-lactide)(PLA)/Imipenem(Imi) polymer solution. The results showed that the optimized ratio of Ch/PLA polymer solution was ratio of 50:50 and Ch 2 wt% and PLA 10 wt% polymer solution was the best weight percentage for nanofiber preparation. Also, the average diameter of Ch/PLA/Imi nanofibers was 143 nm and measured with ImageJ software. Afterwards, the antibacterial properties of Imi as additives (with different percentages) was studied in the polymer solution. The scanning electron microscopy (SEM) images and antibacterial tests were showed that the electrospun of Ch/PLA/Imi polymeric nanofibers were effective against Gram negative bacteria Escherichia coli (E. coli) and inhibited growth of E. coli. The growth and viability percentage of fibroblast cells with nanofibers in αMEM culture are at desirable levels after 6 days.     

Development and evaluation of novel eucalyptus essential oil liposomes/chitosan composite sponges for medical use

Novel eucalyptus essential oil liposomes (EEOLs)/chitosan composite sponges (EC) were successfully fabricated by electrostatic self-assembly. EEOLs were prepared by the thin-membrane hydration method with sonication and blended with chitosan solution to create the sponges by lyophilization. The observations of transmission electron microscopy (TEM) and scanning electron microscopy (SEM) confirmed the existence of eucalyptus essential oil in the lipid bilayer of liposomal membrane and the location of the liposomes in positive holes formed by the protonated amino groups of chitosan. The average size of EEOLs was about 60 nm. Fourier transform infrared (FTIR) analysis showed the destroy of inter- and intramolecular hydrogen bonding among chitosan chains and the construction of the intermolecular hydrogen bonding between chitosan and molecules on the surface of EEOLs. The incorporation of EEOLs in chitosan sponges slightly decreased the porosity, fluid absorptivity, gas permeability and hemostatic property of sponges, but increased their biodegradation ability. EC exhibited more rapid and efficient microbicidal effects against Staphylococcus aureus (S. aureus), Pseudomonas aeruginosa (P. aeruginosa) and Candida albicans (C. albicans) than pure chitosan sponges. EC showed no toxicity toward human HEK293T cells and no significant adverse effect on cell attachment and proliferation of HEK293T cells. This inherent behaviour can be exploited to apply in the medical field.     

Bioactive and multifunctional textile using plant-based madder dye: Characterization of UV protection ability and antibacterial activity

In the present work the natural madder dye (Rubia tinctorum L.) was applied to the simultaneous dyeing and functionalization of polyester (PET) fabric. In the first part of the study the color performance and the durability were revealed for exhaustion dyed fabric. The dyed fabric was then characterized with respect to ultraviolet (UV) protection ability and antibacterial activity against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). CIELab color coordinates, namely the positive a* and b* values, confirmed a yellow/orange color of the dyed fabric. From durability tests, the color showed a moderate to good light fastness and good to excellent fastness to washing and rubbing. The madder dye improved both the UV protective performance and the antibacterial activity of the fabric. With 3 % on weight of fiber (owf) the UV protection factor increased up to 106, and the antibacterial activity up to 86 % against both types of bacteria tested.     

Preparation and characterization of cellulose nanofiltration membrane through hydrolysis followed by carboxymethylation

Bamboo cellulose (BC) is hydrophilic, biodegradable and inexhaustible. The bamboo cellulose membrane (BCM) is one of the best materials to replace petroleum-based polymer film for water purification. In this study, the N-methylmorpholine-N-oxide (NMMO) was used as a solvent to dissolve cellulose 6 wt.%, and regenerated cellulose membrane was prepared by phase inversion. A new kind of cellulose nanofiltration membrane (BC-NFM) was obtained by the hydrolysis and carboxymethylation of dense cellulose membrane (BCM). The modification was carried out through hydrolysis followed by carboxymethylation. The BC-NFM was characterized by XRD, FT-IR, SEM and thermal analysis. BC-NFM performance evaluation instrument were used to evaluate retention rate and water flux of nanofiltration membrane. BCM was immersed in 1 mol/l NaOH and 3 wt/v.% chloroacetic acid solution to obtain BC-NFM. By calculating, pore size of nanofiltration membrane was 0.63 nm. With a pressure of 0.5 MPa, the water flux of nanofiltration membrane for Na₂SO₄ solution was 10.32 l/m²h, and the retention rate was 68.4 %. The water flux for NaCl solution was 13.12 l/m²h, and the retention rate was 34.9 %. And the retention rates were 93.0 % and 98.9 % for methyl orange and methyl blue, respectively. The stability of the nanofiltration membrane was measured by the thermal analyzer, following the order of BC>BCM>BC-NFM. The prepared cellulose nanofiltration membrane exhibited good stability in water treatment process, and can be used to remove organic compounds in aqueous solutions.     

Application of MCT-βCD to Modify Cellulose/Wool Blended Fabrics for Upgrading Their Reactive Printability and Antibacterial Functionality

Pre-loading of monochlorotriazinyl β-Cyclodextrin (MCT-βCD) onto/within viscose/wool (V/W) and cotton/wool (C/W) blended fabrics provide hosting cavities that can form host-guest inclusion complexes with reactive dyes in postprinting as well as with triclosan derivative or silver nanoparticles/hyperbranched polyamide-amine (AgNPs/HBPAA) composite in subsequent final antibacterial finishing step. Coloration properties, antibacterial activity against (S. aureus) and (E. coli) pathogenic bacteria, durability of the obtained products, according to the above mentioned route, to wash, surface morphology and composition of selected samples were investigated. Results obtained signify that premodification of the nominated substrates with MCT-βCD (10 g/l), followed by reactive printing with mono-or bifunctional reactive dye (20 g/l), and subsequent post-finishing with triclosan derivative or AgNPs/HBPAA composite (15 g/l each) is an efficient treatments sequence for attaining reactive prints with significant antibacterial efficacy and noticeable durability to wash. Surface depositions of selected active ingredients were also confirmed using SEM and EDX analysis.     

Durable antibacterial cotton modified by silver nanoparticles and chitosan derivative binder

This article focuses on the functional finishing of textiles using silver nanoparticles (AgNPs) and chitosan derivative binder, which was synthesized by a modification of chitosan using α-ketoglutaric acid. The binder covalently linked to cotton fabric via esterification of the hydroxyl groups on the cotton surface, and tightly adhered to surface of the AgNPs by coordination bonds. As a result, the coating of AgNPs on the cotton fabric showed excellent antibacterial property and laundering durability. After 30 consecutive laundering cycles, the Ag content on the fabrics decreased to 37.6 %, but the bacterial reduction rates against both S. aureus and E. coli were maintained over 95 %. It has potential applications in a wide variety of fields such as sportswear, socks, and medical textile.     

Physico-chemical characteristics of a seed fiber arised from <Emphasis Type="Italic">Pergularia Tomentosa</Emphasis> L.

In the present paper, we analyze a seed fiber arising from Pergularia tomentosa L. (PTL). It was, primarily, characterized using different techniques. The morphology of the fibers was observed via Scanning Electron Microscopy (SEM). They are also checked in term of decomposition behavior through TGA/DTG instrument. The cristallinity index was determined using XRD and it was about 52 %. The chemical composition in terms of moisture percent, ash, waxes and fats, lignin, hemicellulose and cellulose were, respectively 8.5 %, 2.74 %, 1.88 %, 8.6 %, 16 % and 43.8 %. The contact angle value was measured and the evolution of drop profile was captured with video-camera using GBX Tensiometer Surfaces Sciences Studies. Further, fibers were dyed with Methylene Blue, Direct Red 79, Sumifix supra yellow 3RF and Reactive Blue 198. Color coordinates (ΔL*, Δa*, Δb*, ΔC* and ΔH*) of the samples were so measured. All obtained data were compared to cotton fibers and some other cellulosic fibers. The Results revealed that, based on such properties, PTLF could be a competitive fiber in many applications field (textile weaving, composites, etc).     

Extraction,Dyeing, and Antibacterial Properties of <Emphasis Type="Italic">Crataegus Elbursensis</Emphasis> Fruit Natural Dye on Wool Yarn

Fruits obtained from shrubs of the Crataegus elbursensis (C. elbursensis) plant demonstrate significant antioxidant and antibacterial properties. In this study, natural dye was sono-extracted from fresh and dried fruits and applied in dyeing and antibacterial finishing of wool. The maximum sono-extraction yield was obtained when optimal conditions of ethanol/ water (4/1 v/v) as extracting solvent, time 30 min, pH 4, temperature 50 oC, and C. elbursensis concentration 10 g/l were used. When wool yarns were dyed with the extracted natural dye, the maximum dye uptake was achieved using dye concentration 75 % owf, and dyeing condition of 100 oC, 60 min, pH 4, and LR 100:1. Different metal salts like aluminum sulfate, copper sulfate, and tin chloride were applied on wool by pre-mordanting method and their effects on dye uptake, color variation, and color fastness were examined. Results showed that the natural dye itself had relatively high uptake and good color fastness on un-mordanted wool. Further, each mordant had different effect on dye uptake, color variation, and color fastness properties depending on its coordination ability with dye molecules and wool chains. Moreover, dyed yarns showed good antibacterial activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) bacteria.     

Antibacterial cotton fabric with enhanced durability prepared using L-cysteine and silver nanoparticles

L-cysteine (Cys) and silver nanoparticles (Ag NPs) were successfully linked onto the cotton fabric surfaces. The Cys molecules were covalently linked to the cotton fibers via esterification with the cellulose hydroxyl groups, and the Ag NPs tightly adhered to the fiber surface via coordination bonds with the Cys thiol groups. As a result, the Ag NPs coating on the cotton fabric showed an excellent antibacterial function with an outstanding laundering durability. The bacterial reduction rates (BR) efficiency reached 100 % for Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). After 50 consecutive laundering cycles, the bacterial reduction rates (BR) against E. coli and S. aureus were maintained over 97 %. It has potential applications in a wide variety of fields such as sportswear, socks, and medical textile.