Polyhexamethylene Guanidine Hydrochloride Research Articles

Antibacterial and mothproofing wool fabrics modified by M-Arg/PHMG and ZnO

The increasing focus on sustainable and eco-friendly materials has sparked a growing interest in wool as a natural fiber for sustainable fashion, thanks to its skin-friendly properties, warmth, breathability, renewability and biodegradability. The advancement of wool fabrics with durable antimicrobial and moth-resistant qualities could significantly enhance the utilization of wool in the production of high-quality textiles. This study investigates the synthesis of M−Arg and polyhexamethylene guanidine hydrochloride (PHMG) and their application in the surface modification of wool fibers, with an evaluation of the antimicrobial properties of the treated fabrics. Initially, plasma was used to pre-treat the wool fibers, followed by the adsorption of M−Arg and PHMG and ZnO in situ on the fiber’s surface. The antibacterial effectiveness against gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli) microorganisms was assessed through antibacterial testing of the M−Arg/PHMG/ZnO-Fiber (MPN-Fiber). Results showed that the MPN-Fiber exhibited a significantly higher antimicrobial rate compared to untreated wool fiber. The prepared MPN-Fiber inhibited E. coli and S. aureus by 99.64 ± 1.04 % and 96.47 ± 2.14 %, respectively. Additionally, the MPN-fiber has good washing resistance (20 times, lose only 10 %). The experimental results clearly demonstrated that the MPN-Fiber exhibited exemplary antibacterial and moth-proof properties, confirming the success of the innovative surface modification approach.

Development of antifouling antibacterial polylactic acid (PLA) -based packaging and application for chicken meat preservation

Microbial contamination is the leading cause of food spoilage and food-borne disease. Here, we developed a multifunctional surface based on polylactic acid (PLA) bioplastic with antifouling and antibacterial properties via a facile dual-coating approach. The surface was designed with hierarchical micro/nano-scale roughness and low surface energy. Bactericidal agent polyhexamethylene guanidine hydrochloride (PHMG) was incorporated to endow the film with bactericidal activity. The film had good superhydrophobic, antifouling and antibacterial performance, with a water contact angle of 154.3°, antibacterial efficiency against E. coli and S. aureus of 99.9 % and 99.6 %, respectively, and biofilm inhibition against E. coli and S. aureus of 63.5 % and 68.9 %, respectively. Synergistic effects of antibacterial adhesion and contact killing of bacteria contributed to the significant antibacterial performance of the film. The biobased biodegradable film was highly effective in preventing microbial growth when applied as antibacterial food packaging for poultry product, extending the shelf life of fresh chicken breast up to eight days.

A systematic review and BMD modeling approach to develop an AOP for humidifier disinfectant-induced pulmonary fibrosis and cell death

Dosimetry modeling and point of departure (POD) estimation using in vitro data are essential for mechanism-based hazard identification and risk assessment. This study aimed to develop a putative adverse outcome pathway (AOP) for humidifier disinfectant (HD) substances used in South Korea through a systematic review and benchmark dose (BMD) modeling. We collected in vitro toxicological studies on HD substances, including polyhexamethylene guanidine hydrochloride (PHMG-HCl), PHMG phosphate (PHMG-p), a mixture of 5-chloro-2-methyl-4-isothiazolin-3-one and 2-methyl-4-isothiazolin-3-one (CMIT/MIT), CMIT, and MIT from scientific databases. A total of 193 sets of dose-response data were extracted from 34 articles reporting in vitro experimental results of HD toxicity. The risk of bias (RoB) in each study was assessed following the office of health assessment and translation (OHAT) guideline. The BMD of each HD substance at different toxicity endpoints was estimated using the US Environmental Protection Agency (EPA) BMD software (BMDS). Interspecies- or interorgan differences or most critical effects in the toxicity of the HD substances were analyzed using a 95% lower confidence limit of the BMD (BMDL). We found a critical molecular event and cells susceptible to each HD substance and constructed an AOP of PHMG-p- or CMIT/MIT-induced damage. Notably, PHMG-p induced ATP depletion at the lowest in vitro concentration, endoplasmic reticulum (ER) stress, epithelial-to-mesenchymal transition (EMT), inflammation, leading to fibrosis. CMIT/MIT enhanced mitochondrial reactive oxygen species (ROS) production, oxidative stress, mitochondrial dysfunction, resulting in cell death. Our approach will increase the current understanding of the effects of HD substances on human health and contribute to evidence-based risk assessment of these compounds.

EVALUATION OF THE EFFICACY OF CHLORINE-CONTAINING COMMERCIAL PRODUCTS FOR WATER DECONTAMINATION AGAINST COLIFORM BACTERIA

Problem. Water is a key factor in the transmission of intestinal infections. During war conflicts, the risk of outbreaks of such infections increases due to infrastructure damage, the inaccessibility of central water supplies, and the impossibility of governmental institutions to control drinking water quality. In such situations, the need arises for household water treatment methods. Aim. To evaluate the efficacy of seven commercial water treatment products available in the Ukrainian market against enteric bacteria and to compare their efficacy. Methods. The activity of water purification products against the model microorganism Escherichia coli ATCC25922 was evaluated using serial dilution methods followed by viable count assessment. The main results: High efficacy of the studied preparations against enteric bacteria was detected. In each test, a significant decrease in the initial titer of Escherichia coli from 1,2·10 6 CFU/cm 3 to ˂ 10 CFU/cm 3 was observed after the exposure time declared by the manufacturer. Conclusions: The studied water treatment products from Ukrainian and foreign manufacturers were effective against enteric bacteria and met the WHO criteria for efficiency, regardless of the nature of the active compound (chlorine dioxide, sodium dichloroisocyanurate, or polyhexamethylene guanidine hydrochloride).

Inhibiting perovskite decomposition by a creeper-inspired strategy enables efficient and stable perovskite solar cells

The commercialization of perovskite solar cells is badly limited by stability, an issue determined mainly by perovskite. Herein, inspired by a natural creeper that can cover the walls through suckers, we adopt polyhexamethyleneguanidine hydrochloride as a molecular creeper on perovskite to inhibit its decomposition starting from the annealing process. The molecule possesses a long-line molecular structure where the guanidinium groups can serve as suckers that strongly anchor cations through multiple hydrogen bonds. These features make the molecular creeper can cover perovskite grains and inhibit perovskite decomposition by suppressing cations’ escape. The resulting planar perovskite solar cells achieve an efficiency of 25.42% (certificated 25.36%). Moreover, the perovskite film and device exhibit enhanced stability even under harsh damp-heat conditions. The devices can maintain >96% of their initial efficiency after 1300 hours of operation under 1-sun illumination and 1000 hours of storage under 85% RH, respectively.

Modified Cellulose Nanocrystals Enabled Antimicrobial Polymeric Films

AbstractThis study presents an antimicrobial polymeric material comprising cellulose nanocrystals (CNCs) grafted with an antimicrobial oligomer, polyhexamethylene guanidine hydrochloride (PHGH). A one‐pot reaction is implemented to graft PHGH onto CNCs, creating a non‐leaching and nano‐sized antimicrobial additive (mCNC). The mCNC is subsequently incorporated into a model polymer, polylactic acid (PLA), with concentrations of 2.5 to 10 wt.% and tested for its antimicrobial activity during dynamic and static contact with Escherichia coli and Bacillus subtilis bacteria. The grafting of PHGH onto CNC is confirmed with Fourier transform infrared spectroscopy (FTIR), X‐ray spectroscopy (XPS) and elemental analysis. The effect of mCNC incorporation at various loading levels on the morphology and physicomechanical properties of PLA is investigated with polarized optical microscope (POM), scanning electron microscope (SEM), dynamic mechanical analysis (DMA), tensile testing, and differential scanning calorimetry (DSC). In terms of the antimicrobial action, the films exhibited potent efficacy against Gram‐positive bacteria (B. subtilis), with growth inhibition of 3.97 to 4.66‐log reduction. However, 10 wt.% of mCNC loading is needed to achieve a significant bacterial inhibition (>6.24‐log) of the Gram‐negative bacteria (E. coli). Overall, the incorporation of PHGH grafted CNCs in polymers provided a non‐leaching antimicrobial film that has potential application in food packaging.

Enhanced mechanical and long-lasting antibacterial properties of starch/PBAT blown films via designing of reactive micro-crosslinked starch

A functional starch (TPS-E) was designed and constructed by incorporating epoxy soybean oil (ESO) and an antibacterial agent polyhexamethylene guanidine hydrochloride (PHMG), then the film was prepared by reaction extrusion and blow molding using TPS-E and poly(butylene adipate-co-terephthalate) (PBAT). The micro-crosslinking structure, forming through ring-opening reaction between the epoxy active site of TPS-E and the end group of PBAT, improved the compatibility of starch/PBAT blend and reduce the dispersed starch phase size, leading to significantly increase the tensile strength. Compared to starch/PBAT films, the tensile strength of TPS-E/PBAT in the longitudinal direction increase by 112% with the same starch content of 30%. Furthermore, these TPS-E/PBAT films demonstrated long-lasting antibacterial performance with a 98% inhibition ratio even after 10 cycles, without any observed leaching of the antibacterial agent, highlighting the high coupling efficiency of PHMG. TPS-E with the degradable ESO also promotes the degradation of PBAT. Thus, an important method of synergistic improving the mechanical, degradable and antibacterial properties of blown films through the design of reactive micro-crosslinked starch structures was established.

Thermomechanical and mechanical properties of biocidal materials based on polyhexamethylene guanidine hydrochloride and polyvinyl alcohol

During the development of polymer science, attention has been attracted to different research areas. The current focus on polymer mixtures is due to their practical significance. Studying the physical and mechanical properties of polymer mixtures has led to a revision of existing basic concepts, the emergence of new research directions and the solution of practical problems. From this point of view, polymer mixtures are similar to copolymerization in achieving specific properties by combining different chemical structures. The use of polymer mixtures allows materials with the desired properties to be obtained at a faster rate than the synthesis of high-molecular compounds. In recent years, numerous studies have been published on the interaction of various polymers, particularly water-soluble and naturally occurring polymers that are safe for humans and the environment. The development of such materials is of great interest due to their high adhesive strength. These materials can be used to obtain polymer films with new valuable properties. This work investigates the potential of improving the thermomechanical and mechanical properties of films for use in construction as polymer biocidal additives by modifying polyhexamethylene guanidine hydrochloride with polyvinyl alcohol. Films based on a polymer-polymer mixture of polyhexamethylene guanidine hydrochloride and polyvinyl alcohol were used as a research object.

ИССЛЕДОВАНИЕ ФУНГИЦИДНЫХ СВОЙСТВ БАКТЕРИЦИДНОГО ПРЕПАРАТА ДЛЯ ЗАЩИТЫ ВИНОГРАДА ОТ МИЛДЬЮ

The paper presents the results of studies of fungicidal properties of bactericidal drug on vine plantations. To test the drug, we used a small-plot experiment with plants of Cabernet Sauvignon variety, cultivated in cover crop with a long-armed bush form. The bactericidal drug contained polyhexamethylene guanidine hydrochloride 9% and alkyldimethylben-zylammonium chloride 1% as active ingredi-ents, as well as functional components and wa-ter. The experiment included variants of differ-ent concentrations of the bactericidal drug (1, 3, 5%), a standard variant using approved fun-gicides (Kurzat, Poliram DF) and a control var-iant − without treatments. The drug at a con-centration of 5% with weak development of downy mildew restrained the development of the disease, with average and epiphytotic de-velopment it was little effective. The effective-ness of the bactericidal drug in protecting against downy mildew at concentrations of 1 and 3% has not been proven. There were no signs of phytotoxicity on vine plants after using the bactericidal drug at the studied doses.

Antibacterial Effect of Two Novel Sealants: A Laboratory-Based Study.

This research sought to assess the impact of polyhexamethylene guanidine hydrochloride (PHMGH) and 1,3,5-triacryloyl hexahydro-1,3,5-triazine (TAT) on the antibacterial activity of an experimental resin sealant. The two experimental sealants were formulated based on previous research, and Streptococcus mutans (S. mutans) was tested for biofilm and planktonic bacteria's antibacterial properties. In 48 hours, 300 L of frozen S. mutans in skim milk was stored in an oven at 37°C in a microaerophilic atmosphere with 5% of CO2 and put on a petri plate containing brain-heart infusion (BHI) broth with agar at 15 g/L. By combining 100 mL of the subculture broth with 900 mL of a sterile saline solution (0.9%) in an Eppendorf tube, the initial inoculum used for the experiments was evaluated. The colonies were measured in colony-forming units per milliliter (CFU/mL) after being counted visually. To measure the antibacterial activity, log CFU/mL was used to express the number of bacteria in the broth that had been in contact with the samples for 24 hours. Outcomes of antibacterial activity against planktonic bacteria and against biofilm development on polymerized materials. The two innovative sealant materials were found to differ significantly from one another, while group 2's mean and standard deviation values were larger. Dental sealants designed with PHMGH and TCPTAT for anticaries application showed less bacterial growth throughout time the cavity prevention properties of the resin sealant.

IMPROVEMENT OF TECHNOLOGICAL STAGES IN BEEKEEPING WITH DISINFECTION MEASURES

Disinfection is a very important technological measure, which is carried out to combat infectious diseases of bees and prevent contamination of beekeeping products with harmful microorganisms. The disinfection procedure is very complex, and its effectiveness depends on a large number of factors: the spectrum of the disinfectant, the method of application, the concentration of the disinfectant, the exposure time, and the properties of the environment to be disinfected. Active components of disinfectants usually affect the metabolism of microorganisms. For disinfection in beekeeping, we can use iodine preparations, bases, acids, quaternary ammonium compounds, oxidizers (hydrogen peroxide, peracetic acid). Effective chemical disinfectants are a warm solution of sodium hydroxide, oxidizers, so these disinfectants are most often used in beekeeping. However, the negative properties of these disinfectants should also be considered. There is no perfect disinfectant. Because of the toxicity and other harmful effects of disinfectants, and often their ineffectiveness, physical methods of disinfection should be implemented whenever possible. The article presents the results of studies of such disinfectants as Septox, PHMG – HC and Crystal-700 in concentrations of 0.25%, 0.5%, 1.5%, as well as a comparative description of their effectiveness during “in vitro” disinfection on test objects (glass, veneer, wax) contaminated with spores of Paenibacillus larvae subsp. larvae and Ascosphaera apis. Test controls were: No. 1 – sterile physiological solution; No. 2 – Desvax (4% formaldehyde solution with 0.05% DMSO), a drug approved for disinfection of bee inventory in Ukraine (Deklaratsiinyi patent 61387A, 2003, Rudenko, 2012). The test objects were immersed in the test solutions and kept for 3, 9, 18 hours. To determine the intestinal toxicity, the test substances were fed to bees and the time and number of dead individuals were monitored. According to the results of the sanitary and hygienic assessment of individual indicators of chemical disinfectants, the best disinfecting properties were demonstrated by 1.5% solutions of polyhexamethyleneguanidine hydrochloride, sodium hypochlorite and Crystal-700, which are environmentally safe, non-toxic, non-volatile, non-aggressive towards metals, plastics, wood, convenient to use. They can be recommended for long-term antiseptic protection, preventive, forced, current and final disinfection for bacterial, fungal and viral infections.

Fabrication of Multifunctional Cotton Fabrics with Antibacterial, Hydrophobic, and Dyeing Performance.

Cotton fibers have received considerable attention owing to their functional properties. Current research endeavors have shifted toward devising straightforward and versatile approaches for modifying cotton fibers. Herein, a simple and feasible method was proposed for preparing multifunctional cotton fibers. This method entailed subjecting cotton fibers to alkaline conditions, prompting the epoxy group in epoxidized soybean oil to engage in a ring-opening reaction with the hydroxyl group in cotton fibers and the amino group in polyhexamethylene guanidine hydrochloride. Epoxidized soybean oil acted as a bridge, forming a covalent bond between polyhexamethylene guanidine hydrochloride and cotton fibers, thereby facilitating the cationization of cotton fibers. Structural changes in the modified cotton fibers were characterized using Fourier transform infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and energy-dispersive X-ray spectroscopy. The modified cotton fibers were also evaluated for their dyeing, antibacterial, and hydrophobic properties. The results demonstrated that the dye exhaustion and total dye utilization of modified cotton in salt-free dyeing were much higher than those of raw cotton in conventional dyeing. The water contact angle of the modified cotton fiber reached 139.5°, and their antibacterial properties were partially improved. Importantly, this chemical modification was performed under mild conditions, highlighting its simplicity and environmentally friendly nature.

Biological Properties and Antibiotic Resistance of <i>Klebsiella pneumoniae</i> and Its Role in the Etiological Structure of Community-Acquired Pneumonia Pathogens

Background. In a novel coronavirus pandemic, the most common complications of viral pneumonia are secondary infections of bacterial and fungal etiology. At the same time, the spread of multidrug-resistant bacteria remains a global threat to public health. One of such microorganisms of the Enterobacteriaceae family is Klebsiella pneumoniae, which belongs to dangerous resistant pathogens of the ESKAPE group.The aim of the study was the comparative analysis of the biological properties of classical and hypermucoid strains of K.pneumoniae isolated from patients with community-acquired pneumonia (CAP): characterization of their sensitivity to antibacterial drugs, Klebsiella bacteriophage, and a disinfectant (polyhexamethylene guanidine hydrochloride), as well as assessment of the strains’ virulence in the model of experimental infection in white mice.Material and methods. 56 strains of Klebsiella isolated in diagnostic quantities from patients’ sputum samples were studied. Species identification of cultures was carried out using bacteriological and mass spectrometric methods. The sensitivity of bacteria to antibiotics, bacteriophage, and the disinfectant was determined in accordance with regulatory documents.Results. In the course of the study, 243 gram-negative cultures were isolated, of which 30% were bacteria of the genus Klebsiella spp. An analysis of their species composition showed that K.pneumoniae occupied a dominant place in the structure. Based on colony morphology, Burri-Gins smear staining, and a positive string test, 14 strains with a hypermucoid phenotype were identified. These strains differed from the classic K.pneumoniae strain by the presence of a thicker capsule in smears, virulence in white mice (DCL≤103 mc), and increased resistance to commercial Klebsiella bacteriophage. At the same time, they were characterized by a wider spectrum of sensitivity to antibiotics. There were no significant differences in sensitivity to the disinfectant in strains of both morphotypes.Conclusion. The results obtained demonstrated the important role of K.pneumoniae in the etiological structure of CAP pathogens.

Expand and Sensitize: Guanidine‐Functionalized Exopolysaccharide Nanoparticles Cause Bacterial Cell Expansion and Antibiotic Sensitization

AbstractConventional antibacterial agents and mechanisms are frequently observed to be ineffective due to the evolution of bacteria to the strains with stronger antibiotic resistance, and hence developing alternative antibacterial materials and mechanisms is urgently needed. Here, guanidine‐functionalized exopolysaccharide (EPS) nanoparticles (termed EPGNs) with durable antibacterial and antibiofilm activities are developed. Very interestingly, the EPGNs obtained by the reaction of EPS, epichlorohydrin, and polyhexamethylene guanidine hydrochloride exhibit an unconventional antibacterial mechanism, i.e., they can induce substantial bacterial cell expansion by upregulating the SulA and DicB proteins that are responsible for cell division inhibition, along with the increase of reactive oxygen species production, bacterial cell surface disruption, and bacterial ribosomal RNA degradation. The transcriptome analysis reveals that EPGNs can hinder cell motility, induce loss of cell integrity, decrease the resistance of bacteria to oxidative stress, and finally lead to cell death. Moreover, EPGNs can effectively accelerate the bacteria‐infected wound healing. This work provides the first example that nanomaterials can cause bacterial cell expansion by affecting intracellular structures and inhibiting cell division, and it may inspire other researchers to investigate the effect of antibacterial materials on the change of bacterial volume and design unconventional antibacterial materials/strategies.

Stability of modified technetium-containing magnesium potassium phosphate matrix under repository conditions with regard to biogeochemical effects

In this work, the biological stability of magnesium potassium phosphate (MPP) matrix was assessed for the first time under conditions modelling near-surface and deep repositories of radioactive waste (RW) containing technetium. It was found that MPP-matrix is potentially susceptible to microbial degradation, so it is necessary to introduce modifying additives. The efficiency of introduction of modifying additives - tetraphenylphosphonium chloride (TPP), thiourea (THIO), polyhexamethyleneguanidine hydrochloride (PHMG), polyethyleneimine (PEI), shungite (SHU), chalcopyrite (CP), orpiment (ORP) at immobilisation of pertechnetate ion in MPP-matrix has been estimated. The mechanical strength and water resistance of the obtained compounds were investigated. The maximum leaching rate of technetium was found to be 0.34 g cm-2 day-1 from the blank sample without additives. The addition of ORP and PHMG reduces the leaching rate of technetium by 90% and 62%, respectively, relative to the pure sample. The addition of other modifying additives reduced the leaching rate of pertechnetate ions by 15–25% on average. At the same time, the addition of PEI and THIO led to a decrease in compressive strength below the standard requirement of 4.9 MPa.a. Samples containing PHMG and ORP up to 0.5 wt% showed higher safety margin compared to the blank sample. ORP, PHMG and TPP can be proposed as modifying additives to reduce microbial activity during immobilisation of pertechnetate ion using MPP matrix.

Prospects for Application of Guanidine-Containing Organomineral Complexes as Biocidal Functional Additives for Waterborne Polymer Materials

The possibility of using organomineral complexes of polyhexamethylene guanidine hydrochloride as a functional additive for a waterborne paint based on polyvinyl acetate has been investigated. Organomineral complexes containing 20 and 30 wt % guanidine polymer have been obtained, with intercalation of polyguanidine chains into the interlayer space of montmorillonite being observed. It has been revealed that the stability of the polymer film to water is retained when organomineral complexes are introduced into a polyvinyl acetate dispersion, whereas the water resistance of the film sharply decreases when free polyguanidine is added. There was no significant influence of organomineral complexes on the rheological characteristics of the dispersion and its sedimentation stability. Testing of waterborne paints with various additives has shown that introduction of organomineral complexes into the material prevents the coating from fouling by biofilms of gram-positive bacteria Staphylococcus aureus and Rhodococcus erythropolis, with the hardness, water resistance, and water-vapor transmission of the coatings being retained at a satisfactory level.

Polyhexamethylene guanidine hydrochloride as promising active ingredient for oral antiseptic products to eliminate microorganisms threatening the health of endangered wild cats: a comparative study with chlorhexidine digluconate.

The aim of this study was to evaluate the antimicrobial efficacy of polyhexamethylene hydrochloride guanidine (PHMGH) compared to chlorhexidine digluconate (CLX) for use as an oral antiseptic during dental procedures in wild cats. This research is crucial due to limited information on the diversity of oral microorganisms in wild cats and the detrimental local and systemic effects of oral diseases, which highlights the importance of improving prevention and treatment strategies. Samples were collected from the oral cavities of four Puma concolor, one Panthera onca, and one Panthera leo, and the number of colony-forming units per milliliter (CFU/mL) was counted and semi-automatically identified. The antimicrobial susceptibility profile of bacterial isolates was determined using minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and time-kill kinetics of PHMGH and CLX. A total of 16 bacterial isolates were identified, consisting of six Gram-positive and 10 Gram-negative. PHMGH displayed MIC and MBC from 0.24 to 125.00 μg/mL, lower than those of CLX against three isolates. Time-kill kinetics showed that PHMGH reduced the microbial load by over 90% for all microorganisms within 30 min, whereas CLX did not. Only two Gram-positive isolates exposed to the polymer showed incomplete elimination after 60 min of contact. The results could aid in the development of effective prevention and treatment strategies for oral diseases in large felids. PHMGH showed promising potential at low concentrations and short contact times compared to the commercial product CLX, making it a possible active ingredient in oral antiseptic products for veterinary use in the future.

Toxicity of benzethonium chloride and polyhexamethylene guanidine hydrochloride mixtures on Daphnia carinata: synergistic and antagonistic effects at specific ratios

Throughout the coronavirus (COVID-19) pandemic, the sanitizing products benzethonium chloride (BEC) and polyhexamethylene guanidine hydrochloride (PHMG-H) were widely used; however, few studies have investigated their combined toxicity to organisms. In the present study, acute toxicity and genotoxicity of BEC, PHMG-H, and the combination of the two were investigated as endpoints using Daphnia carinata as the model organism. For individual reagents, PHMG-H was found to be more toxic than BEC in terms of both mortality and genotoxicity. DNA damage and survival rate were used as toxicity endpoints. The interaction was evaluated with the concentration addition (CA) model via toxic unit (TU) approach and additive index (AI) method in mixtures at different ratios in TU. Only the binary mixture BEC + PHMG-H at the ratio 1:9 in TU was regarded as synergistic, while all others indicated increased antagonistic effects as the proportion of BEC increased over the PHMG-H concentration. The findings here benefit understanding surrounding precisely how BEC and PHMG-H interact at different mixing ratios, and can assist with the evaluation of risk assessments for binary mixtures in aquatic ecosystems.

Polyhexamethylene guanidine hydrochloride‐functionalized wound dressings: Physical, mechanical and biological evaluations

AbstractThe objective of the present study is fabrication of wound dressing membranes with effective antibacterial activity, good biocompatibility with fibroblast cells, appropriate mechanical properties in both dry and wet states to potentially provide physical protection to wounds at different stages of healing, and the ability to maintain an optimum moist environment over the wounded area. To achieve this, a new silane functional polyhexamethylene guanidine hydrochloride was synthesized and utilized as a crosslinker for a polymeric matrix consisting of poly(vinyl alcohol) and gelatin. Thin monolayer films of the resulting polymeric networks were characterized and subjected to different physical and biological assays. The tensile test results indicated that the prepared dressing membranes exhibit good tensile strength in both dry (44 MPa) and hydrated (700 KPa) states. The fluid handling capacity of the dressings was found to be in the range of 2.23 to 2.29 g 10−1 m−2 day−1, which is appropriate for treating wounds with “light” to “moderate” exudate levels. The MTT assay showed excellent biocompatibility, evidenced by high fibroblast cells viability cultured directly over dressings (over 70%) or cultured in media containing the leachates extracted from the dressings (over 90%). Moreover, the dressings exhibited potent antibacterial activity against Staphylococcus aureus (87% killing) and Escherichia coli (99% killing) bacterial strains.

Preparation of grafted starch by IPDI coupling and its antibacterial properties

Antibacterial acetate grafted starch (AGS) was synthesized by isophorone diisocyanate (IPDI) coupling acetate esterified starch (AST) and the antimicrobial agent polyhexamethyleneguanidine hydrochloride (PHMG), and the antimicrobial properties of AGS were evaluated. The process parameters of AGS were: IPDI reacted with PHMG at 120 °C for 1 h, then, reacted with starch at 60 °C for 3 h. The grafting yield of PHMG and starch reached 28.43%. The Fourier transform infrared spectroscopy (FTIR) and Nuclear magnetic resonance (1H NMR) showed that the binding of IPDI to PHMG was successfully grafted on the AS. The antibacterial effect of AGS was investigated. AGS produced inhibition zones and confirmed its significant inhibitory effect on Escherichia coli and Staphylococcus aureus, as the grafting yield increased, the inhibition effect on bacteria became stronger. When the grafting yield was 28.43%, the inhibition rate of AGS was 90.24% for Escherichia coli. and 94.45% for Staphylococcus aureus. The experiments of water washing showed that after AGS was washed 10 times with water, the inhibition rate of AGS to E. coli. only reduced 3.04% and that of S. aureus 2.95%, indicating that the combination of PHMG and starch was stable and the inhibition effect was long-lasting, AGS has huge potential to be developed into antibacterial material.