Tailoring of smart textiles using temparature and pH responsive hydrogel as a carrier of antimicrobial substances

Namen raziskave je bil razvoj novih temperaturno in pH-odzivnih pametnih tekstilij s sočasno nadzorovano poroznostjo in uravnavanjem vlage ter proaktivno protimikrobno zaščito, zagotovljeno preko nadzorovanega sproščanja protimikrobnih učinkovin in oblikovanja biobariere. Z uporabo disperzijske polimerizacije je bil sintetiziran hidrogel na podlagi poli(N-izopropilakrilamida) in hitozana (PNCS) v mikro (PNCS_M) in nano velikostnem (PNCS_N) razredu. Velikost delcev hidrogela PNCS je vplivala na njegove odzivne lastnosti. Hidrogel PNCS_M je izkazal boljšo proaktivno poroznost in uravnavanje vlage ter večjo občutljivost na spremembe temperature, hidrogel PNCS_N pa je ob superiornem izločanju vlage izkazal intenzivnejšo odzivnost na spremembo pH. Obdelava vlaken s 30-sekundno kisikovo plazmo je izboljšala navzemanje in razporeditev hidrogela PNCS_N na vlaknih ter s tem izboljšanje želenih temperaturno in pH-odzivnih lastnosti funkcionaliziranih vzorcev. Za dosego proaktivnega protimikrobnega delovanja so bila v delce hidrogela PNCS_M vstavljena različna protimikrobna sredstva, tj. AgCl, koloidno srebro in eterično olje (EO) šetraja (Satureja montana), ki delujejo po principu nadzorovanega sproščanja, ter 3-(trimetoksisilil) propildimetiloktadecil amonijev klorid (Si-QAC) in (3-aminopropil)trietoksisilan (APTES), ki delujeta po principu oblikovanja biobariere. Pri tem je bilo doseženo odlično protimikrobno delovanje ter temperaturno pogojeno nadzorovano sproščanje srebra, čeprav je slednje nekoliko poslabšalo sposobnost proaktivnega uravnavanja vlage vzorcev ob spremembah temperature in pH. Za vstavitev hidrofobnega EO šetraja v delce hidrogela na vlaknih je bil sintetiziran hidrogel PNCS z vključenim &#946-ciklodekstrinom (PNCS/CD). Slednji je izboljšal temperaturno odzivnost hidrogela ter s tem omogočil povišanje koncentracije hitozana v strukturi hidrogela. To je zagotovilo sinergistično protimikrobno delovanje med biobariero hitozana in proaktivnim sproščanjem EO šetraja. V primeru kombinacije hidrogela PNCS_M ter Si-QAC in APTES so postopek nanosa, koncentracija in kemijska struktura polisiloksanskih matric pomembno vplivali na odzivne in zaščitne lastnosti ter citotoksičnost funkcionaliziranih vzorcev. Dvostopenjski postopek nanosa, ki je vključeval najprej nanos hidrogela PNCS_M z naknadnim nanosom 0,5-odstotnega Si-QAC, je zagotovil odlično protimikrobno aktivnost funkcionaliziranega vzorca, a je ta izkazal močno citotoksičnost. Ob zamenjavi Si-QAC s 4-odstotno koncentracijo APTES je bila dosežena odlična protimikrobnost, necitotoksičnost in ohranjene odzivne lastnosti. Med postopkom elektropredenja je bil hidrogel PNCS_M vstavljen v vlakna PLA, kar je zagotovilo izdelavo vlaknatih kompozitov z odzivnimi lastnostmi in proaktivnim sproščanjem ultravijoličnega (UV) barvila.The aim of the research was to develop new temperature and pH responsive smart textile materials with simultaneous controlled porosity, moisture management and pro-active antimicrobial protection, provided by controlled release of antimicrobial substances and bio-barrier formation. Hydrogels based on poly-N(isopropylacrylamide) and chitosan with micro- (PNCS_M) and nano-size (PNCS_N) particles were synthesized using dispersion polymerisation. The particle size of PNCS hydrogels influenced their responsive properties. On the fibre surface, PNCS_M hydrogel showed better pro-active porosity and moisture management properties and greater temperature sensitivity, while PNCS_N hydrogel showed superior moisture release and greater pH responsiveness. The 30-second oxygen plasma treatment of fibres improved adsorption and distribution of the PNCS_N hydrogel on fibre surface, which improved the desired temperature and pH responsive properties of functionalised samples. In order to achieve the proactive antimicrobial activity, different antimicrobials, i.e. AgCl, colloidal silver and savory (Satureja montana) essential oil (EO) with the working mechanism based on controlled release, or 3-(trimethoxysilyl) propyl-dimethyltetecyl ammonium chloride (Si-QAC) and (3-aminopropyl) triethoxysilane (APTES) with the working mechanism based on the formation of a bio-barrier, were incorporated into the PNCS hydrogel particles. An excellent antimicrobial activity and temperature related controlled release of silver was achieved, although the presence of silver compounds repressed the temperature and pH-related moisture management of samples. For the embedment of the hydrophobic savory EO into hydrogel particles, PNCS hydrogel with incorporated &#946-cyclodextrins (PNCS/CD) was synthesized. The latter improved the temperature responsive properties of the hydrogel and allowed an increase in the chitosan concentration, which resulted in the synergistic antimicrobial activity provided by the bio-barrier formed by chitosan and a pro-active release of the savory EO. When combining PNCS hydrogel and Si-QAC or APTES, the application procedure, concentration and the chemical composition of polysyloxane matrix greatly influenced the responsive and protective properties, as well as the cytotoxicity of functionalised samples. The two-step application procedure, including the application of first PNCS_M hydrogel and then 0.5 % Si-QAC, ensured an excellent antimicrobial activity, although the sample showed high cytotoxicity. When Si-QAC was replaced with a 4% concentration of APTES, an excellent antimicrobial activity, noncytotoxicity and preserved responsiveness were obtained. The electrospinning procedure was used for the formation of composite PNCS_M hydrogel and PLA fibres with stimuli responsive properties and pro-active release of the ultraviolet (UV) dye

Stimuli-responsive Hydrogels for Textile Functionalisation: A Review

This article reviews hydrogels used for the functionalisation of textile materials. Hydrogels are reviewed according to their reason for incorporation, aspects of crosslinking, stimuli-responsive characteristics and particle size. A more in-depth focus on the effect of hydrogel particle size is provided, where macrogels, microgels and nanogels for textile functionalisation are considered. The advantages and disadvantages of each size group are presented. Furthermore, the correlation between synthesis conditions and the sizes of hydrogel particles is discussed, in addition to the applications of macro-, micro- and nanogels to textile materials and their intended uses

Sustainable and cost-effective functionalization of textile surfaces with Ag-doped TiO2_2/polysiloxane hybrid nanocomposite for UV protection, antibacterial and self-cleaning properties

In this work, TiO$_2$ was incorporated into the surface of cotton fabrics by an in situ sol–gel/hydrothermal approach. Dimethyloctadecyl [3-(trimethoxysilyl) propyl] ammonium chloride (SiQAC) was added as a bio-barrier Si precursor to enhance the synergistic effect/binding of TiO$_2$ to the surface of cotton fabric. A small amount of silver nitrate (AgNO$_3$) was added to produce Ag-doped TiO$_2$-coated fabric during hydrothermal treatment. The treated cotton fabric samples were characterized by scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDS), Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction spectroscopy (XRD) to determine the surface morphology, chemical composition, chemical bonding and crystal structure, respectively. These results confirmed the successful application of well-dispersed TiO$_2$, Ag and SiQAC on the surface of cotton fabric. The cotton fabric functionalized with TiO$_2$ + SiQAC + Ag nanocomposite exhibited superior antibacterial activity against Escherichia coli and Staphylococcus aureus, very good UV protection and excellent self-cleaning performance, which were maintained even after repeated washings. The wash resistance of the newly developed TiO$_2$-based hybrid nanocoating was attributed to the formation of the SiQAC polysiloxane matrix, which served as an anchoring site for the Ag-doped TiO$_2$ through the formation of Si–O–Ti bonds. The enhanced photocatalytic activity of TiO$_2$ in the coating was attributed to the formation of the Ag/AgCl/TiO$_2$ heterostructure, which is promising for the surface and interface engineering of TiO$_2$-modified fabric

Antibacterial activity and biodegradation of cellulose fiber blends with incorporated ZnO

This research aimed to study the influence of lyocell with incorporated ZnO (CLY) for antibacterial activity and biodegradation of fiber blends composed of viscose (CV), flax (LI), and CLY. Fiber blended samples with an increased weight fraction of CLY fibers were composed, and single CLY, CV and LI fibers were also used for comparison. Antibacterial activity was determined for the Gram-negative Escherichia coli and the Gram-positive Staphylococcus aureus bacteria. The biodegradation of fiber blends was investigated by the soil burial test. The results show that the single CLY fibers exhibited high antimicrobial activity against both E. coli and S. aureus bacteria and that the presence of LI fibers in the blended samples did not significantly affect antibacterial activity against E. coli, but drastically decreased the antibacterial activity against S. aureus. LI fibers strongly promoted the growth of S. aureus and, consequently, impaired the antimicrobial performance of ZnO against this bacterium. The presence of CLY fibers slowed down, but did not prevent, the biodegradation process of the fiber blends, even at the highest ZnO concentration. The soil that was in contact with the fiber blended samples during their burial was not contaminated to such an extent as to affect the growth of sprouts, confirming the sustainability of the fiber blends

Multifunctional antibacterial and ultraviolet protective cotton cellulose developed by in situ biosynthesis of silver nanoparticles into a polysiloxane matrix mediated by sumac leaf extract

A novel facile and eco-friendly procedure for fabrication of multifunctional antibacterial and ultraviolet (UV) protective cotton surface was presented, including premodification of cellulose fibres with a polysiloxane matrix, followed by green in situ biosynthesis of silver nanoparticles (Ag NPs) in the presence of sumac leaf extract as a reducing and stabilising agent. During the biosynthesis, face-centred cubic Ag NPs with an average size of 52–105 nm were generated on the cotton fibres. Increasing the concentration of the AgNO$_3$ precursor resulted in increased concentration of Ag NPs of 50–11,000 mg/kg. The chemically modified cotton surface exhibited excellent antimicrobial and UV protection properties. The additive antibacterial activity of Ag NPs and sumac leaf extract showed biocidal activity against S. aureus even at the lowest Ag NP concentration of 50 mg/kg, and in the case of E. coli, biocidal activity was achieved at a concentration of 340 mg/kg. The presence of both Ag NPs and sumac leaf extract provided UV protection factor greater than 40, irrespective of Ag NP concentration. The increase in Ag NP concentration significantly improved the durability of the coating

Preparation of Functional Stimuli-responsive Polyamide 6 Fabric with ZnO Incorporated Microgel

A new functional, stimuli-responsive microgel coating on polyamide 6 (PA6) fabric with simultaneous temperature (T)- and pH-responsive moisture management, UV protection and photocatalytic self-cleaning properties was prepared by applying poly-(N-isopropylacrylamide)/chitosan (PNCS) microgel in combination with ZnO nanoparticles to PA6 fabric. Two different application procedures were used: (i) the application of PNCS previously functionalized with a ZnO nanoparticles suspension and (ii) the application of PNCS with the subsequent application of a ZnO nanoparticles suspension. The coatings were fabricated on the untreated PA6 fabric as well as on fabric previously modified by the silica matrix created by the sol-gel precursor iSys MTX in order to increase the adsorption ability and uniformity of the coating. The chemical and morphological properties of the coated PA6 samples were determined by SEM and FTIR analyses. Stimuli responsiveness and functional properties were assessed by the moisture content, water vapour transmission rate, water uptake, UV protection and photocatalytic self-cleaning measurements. The results show that the application procedure as well as the pretreatment of PA6 fabric greatly infl uenced the properties of the coating. Accordingly, the most appropriate procedure included the creation of a silica matrix on the PA6 fibres followed by the application of PNCS and subsequent application of ZnO. In this case, the modified PA6 fabric exhibited high T and pH responsiveness due to the swelling/de-swelling activity of the PNCS microgel, as well as good UV protection with UPF equal to 18.8 and photocatalytic self-cleaning properties that are even higher than those in the case of the one-component coating with ZnO

Proactive release of antimicrobial essential oil from a "smart" cotton fabric

Two temperature and pH responsive submicron hydrogels based on poly(N-methylenebisacrylamide), chitosan and β-cyclodextrines (PNCS/CD hydrogel) with varying poly(N-isopropylacrylamide) to chitosan ratios were synthesized according to a simplified procedure, reflecting improved stimuli responsive properties and excellent bio-barrier properties, granted by incorporated chitosan. Hydrogels were applied to cotton-cellulose fabric as active coatings. Subsequently, antimicrobially active savory essential oil (EO) was embedded into the hydrogels in order to develop temperature- and pH-responsive cotton-cellulose fabric with double antimicrobial activity, i.e., bio-barrier formation of chitosan along with the proactive release of savory EO at predetermined conditions. The influence of the hydrogels chemical composition on stimuli responsive and antibacterial properties were assessed. Both PNCS/CD hydrogels showed stimuli responsiveness along with controlled release of savory EO. The chemical composition of the hydrogels strongly influenced the size of the hydrogel particles, their temperature and pH responsiveness, and the bio-barrier forming activity. The increased concentration of chitosan resulted in superior overall stimuli responsiveness and excellent synergy between the antimicrobial activities of the hydrogel and released savory EO

In situ tailoring of Ag-doped-TiO2_2/TPMP/cotton nanocomposite with UV-protective, self-sterilizing and flame-retardant performance for advanced technical textiles

Herein, we present a novel approach to the development of a multifunctional, UV-protective, photocatalytic, antimicrobial and flame-retardant nanocomposite fabric surface. Using a sol–gel/hydrothermal approach, a phosphorus-based flame-retardant 3-(trihydroxysilyl)propyl methylphosphonate (TPMP) in combination with Ag-doped TiO$_2$ was applied to the surface of cotton fibers for the first time, using an aqueous AgNO$_3$ solution as the dopant. The modified cotton fabrics were characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDS) and X-ray diffraction spectroscopy (XRD) to confirm the successful application of Ag-TiO$_2$ and TPMP on the cotton fabric by analyzing the surface morphology, chemical composition, chemical bonding and crystal structure. The functional properties of the modified cotton fabric were determined by measuring the UV protection factor (UPF), burning behavior and thermo-oxidative stability, as well as antibacterial activity against Escherichia coli and Staphylococcus aureus. The results show the formation of a unique nanocomposite matrix of TPMP–polysiloxane on the surface of cotton fibers with well-distributed Ag-TiO$_2$. The formation of TiO$_2$/Ag$_2$O particles on the surface of cellulose fibers was also confirmed. The synergism between all components of the nanocomposite resulted in excellent UV protection in the UVA and UVB region, with a UPF of 50+, self-sterilizing activity against both tested bacteria and enhanced thermo-oxidative stability. Therefore, the novel approach proposed herein is promising for the development of multifunctional, protective surfaces for advanced technical textiles

Proactive Release of Antimicrobial Essential Oil from a “Smart” Cotton Fabric

Two temperature and pH responsive submicron hydrogels based on poly(N- methylenebisacrylamide), chitosan and β-cyclodextrines (PNCS/CD hydrogel) with varying poly(N-isopropylacrylamide) to chitosan ratios were synthesized according to a simplified procedure, reflecting improved stimuli responsive properties and excellent bio-barrier properties, granted by incorporated chitosan. Hydrogels were applied to cotton-cellulose fabric as active coatings. Subsequently, antimicrobially active savory essential oil (EO) was embedded into the hydrogels in order to develop temperature- and pH-responsive cotton-cellulose fabric with double antimicrobial activity, i.e., bio-barrier formation of chitosan along with the proactive release of savory EO at predetermined conditions. The influence of the hydrogels chemical composition on stimuli responsive and antibacterial properties were assessed. Both PNCS/CD hydrogels showed stimuli responsiveness along with controlled release of savory EO. The chemical composition of the hydrogels strongly influenced the size of the hydrogel particles, their temperature and pH responsiveness, and the bio-barrier forming activity. The increased concentration of chitosan resulted in superior overall stimuli responsiveness and excellent synergy between the antimicrobial activities of the hydrogel and released savory EO

Bio-Based Epoxy Adhesives with Lignin-Based Aromatic Monophenols Replacing Bisphenol A

A bio-epoxy surface adhesive for adherence of the metal component species to glass substrate with desirable adhesion strength, converted controlled removal upon request, and bio-based resource inclusion was developed. For the development of resin, three different lignin-based aromatic monophenols, guaiacol, cresol, and vanillin, were used in the chemical epoxidation reaction with epichlorohydrin. The forming transformation process was studied by viscoelasticity, in situ FTIR monitoring, and Raman. Unlike other hydroxyl phenyls, guaiacol showed successful epoxide production, and stability at room temperature. Optimization of epoxide synthesis was conducted by varying NaOH concentration or reaction time. The obtained product was characterized by nuclear magnetic resonance and viscosity measurements. For the production of adhesive, environmentally problematic bisphenol A (BPA) epoxy was partially substituted with the environmentally acceptable, optimized guaiacol-based epoxy at 20, 50, and 80 wt.%. Mechanics, rheological properties, and the possibility of adhered phase de-application were assessed on the bio-substitutes and compared to commercially available polyepoxides or polyurethanes. Considering our aim, the sample composed of 80 wt.% bio-based epoxy/20 wt.% BPA thermoset was demonstrated to be the most suitable among those analyzed, as it was characterized by low BPA, desired boundary area and recoverability using a 10 wt.% acetic acid solution under ultrasound