Biodegradable gelatin/pectin films containing cellulose nanofibers and biguanide polymers: Characterization and application in sweet cherry packaging.

To expand the utilization of gelatin and pectin derived from agricultural by-products, the composite films composed of gelatin, citrus pectin, cellulose nanofibers (CNF), and polyhexamethylene biguanide hydrochloride (PHMB) were prepared through the solvent casting method. Fourier infrared spectroscopy analysis verified the successful integration of CNF and PHMB into the gelatin-pectin matrix. The incorporation of CNF as a reinforcing agent substantially enhanced the barrier capabilities of the composite film. Moreover, the addition of PHMB, functioning as an antimicrobial agent, not only granted the film with antibacterial properties but also improved its physical characteristics and biodegradability. A water contact angle experiment revealed the film presented a certain degree of hydrophobicity. The optimal performances were attained with a composition in which CNF and PHMB constituted 8 % and 3 %, respectively, of the total weight of gelatin and pectin. As a packaging film, the composite film demonstrated its effectiveness by reducing the decay index and weight loss rate of sweet cherries during a 12-day storage period. In the soil degradation test, the composite film exhibited notable structural degradation by the 16th day. Consequently, the composite film will be used as an innovative and biodegradable packaging material to provide a sustainable solution for food packaging industries.

Surface-Modified Carboxylated Cellulose Nanofiber Hydrogels for Prolonged Release of Polyhexamethylene Biguanide Hydrochloride (PHMB) for Antimicrobial Applications.

The surface modification of cellulose nanofibers (CNFs) using a 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)/sodium bromide (NaBr)/sodium hypochlorite (NaClO) system was successful in improving their hydrophilicity. Following that, we fabricated hydrogels containing carboxylated cellulose nanofibers (c-CNFs) and loaded them with polyhexamethylene biguanide (PHMB) using a physical crosslinking method, aiming for efficient antimicrobial uses. The morphological and physicochemical properties of all hydrogel formulations were characterized, and the results revealed that the 7% c-CNFs-2 h loaded with PHMB formulation exhibited desirable characteristics such as regular shape, high porosity, good mechanical properties, suitable gel content, and a good maximum swelling degree. The successful integration of PHMB into the c-CNF matrix was confirmed by FTIR analysis. Furthermore, the 7% c-CNFs-2 h loaded with the PHMB formulation demonstrated PHMB contents exceeding 80% and exhibited a prolonged drug release pattern for up to 3 days. Moreover, this formulation displayed antibacterial activity against S. aureus and P. aeruginosa. In conclusion, the novel approach of c-CNF hydrogels loaded with PHMB through physical crosslinking shows promise as a potential system for prolonged drug release in topical drug delivery while also exhibiting excellent antibacterial activity.

Mechanism of Polyhexamethylene Biguanide Resistance in Purpureocillium lilacinum Strains.

Purpureocillium lilacinum has been recently found to contaminate a 20% (200,000 µg/mL) aqueous solution of polyhexamethylene biguanide hydrochloride (PHMB) . We aimed to elucidate the mechanism underlying the resistance of P. lilacinum to PHMB. First, we induced the PHMB-resistant (IR) strains IFM 67050 (IR) and IFM 65838 (IR) from the type strain P. lilacinum CBS 284.36T via cultivation in a medium containing high concentrations of PHMB. We then analyzed the DNA sequences via Illumina sequencing to evaluate the presence of genetic mutations in IFM 65838 (IR) . Further, we established an IFM 65838 (IR) uridine/uracil auxotrophic strain, and using the orotidine-5'-decarboxylase gene, pyrG as a selection marker, we tried to knockout a mutant gene in IFM 65838 (IR) using the CRISPR-Cas9 genome-editing technique. The growth rates of IFM 67050 (IR) and IFM 65838 (IR) in medium containing PHMB increased, and the minimum inhibitory concentrations (MICs) against PHMB also increased. Based on the DNA sequence analysis, we found a nonsynonymous point mutation in the gene PLI-008146 (G779A) in IFM 67050 (IR) and IFM 65838 (IR) . This point mutation leads to site combinations of splicing changes that cause partial sequences deletion (p.Y251_G281del) in the ΔPLI-008146 locus of IFM 65838 (IR) , and deletion sequences include partial adenosine/AMP deaminase motif (PF00962) orthologous to adenosine deaminase (ADA) (GeneBank: OAQ82383.1) . Furthermore, the mutant gene ΔPLI-008146 was successfully knocked out from the resistanceinduced strain using a novel CRISPR-Cas9 gene transformation method. A considerable reduction in growth rate and MIC against PHMB was observed in the absence of the mutant gene. Therefore, ADA may represent an important resistance factor in PHMB-resistant P. lilacinum.

Polyhexamethylene biguanide hydrochloride (PHMB)-properties and application of an antiseptic agent. A narrative review.

The prevention and management of ocular surface infections is still one of the great challenges for ophthalmologists. The spread of antimicrobial resistance makes it necessary to use antiseptic substances with a broad antimicrobial spectrum. Polyhexamethylene biguanide hydrochloride (Polyhexanide, PHMB) is a broad-spectrum antiseptic with excellent tolerance and a low-risk profile. Its physicochemical action on the phospholipid membrane and DNA replication or repair mechanism, prevents or impedes the development of resistant bacterial strains. PHMB revealed its effective against numerous organisms like viruses, Gram-negative and Gram-positive bacteria, and fungi. Polyhexanide is commonly used as preservative in commercially available disinfecting solutions for contact lens care and in ophthalmic formulations at different concentrations ranging from 1 µg/ml to 50 µg/ml. The administration of 0.02% (200 µg/ml) PHMB is often the first-line therapy of Acanthamoeba keratitis. However, to date, only one close-out randomized controlled study tested the efficacy of 0.02% PHMB in Acanthamoeba keratitis and a phase III study is still ongoing. This paper reviews the antiseptic agent PHMB, focusing on biochemical mechanisms, safety profile and applications in ophthalmology.

Isolation and Characterization of the Polyhexamethylene Biguanide Hydrochloride-Resistant Fungus, Purpureocillium lilacinum.

We isolated a fungus from a 20% (= 200,000 µg/mL) aqueous solution of polyhexamethylene biguanide hydrochloride (PHMB), a widely used antimicrobial and examined its morphology and drug resistance profile. Based on the sequence of the internal transcribed spacer region of ribosomal DNA, the fungus was identified as Purpureocillium lilacinum. Although the P. lilacinum type and resistant strains showed similar morphology, the latter had extremely low PHMB susceptibility and was able to grow in 20% aqueous solution of PHMB, which eliminated the type strain. The minimum inhibitory concentration (MIC) of PHMB for the resistant strain was significantly higher than that of the type strain and other pathogenic filamentous fungi and yeasts. The susceptibility to antimicrobial agents and antifungal agents other than PHMB was similar to that of the type strain, therefore the drug resistance of the isolate was specific to PHMB. Furthermore, we sequenced the genome of the isolate to predict PHMB resistance-related genes. Despite its high resistance to PHMB, no well-known genes homologous to fungal PHMB-resistant genes were detected in the genome of the resistant strain. In summary, P. lilacinum was found to be significantly more resistant to PHMB than previously reported, via an unidentified mechanism of drug resistance.

Safety Assessment of Polyaminopropyl Biguanide (Polyhexamethylene Biguanide Hydrochloride) as Used in Cosmetics.

The Expert Panel for Cosmetic Ingredient Safety (Panel) reviewed the safety of Polyaminopropyl Biguanide (polyhexamethylene biguanide hydrochloride), which functions as a preservative in cosmetic products. The Panel reviewed relevant data relating to the safety of this ingredient and concluded that Polyaminopropyl Biguanide is safe in cosmetics in the present practices of use and concentration described in the safety assessment, when formulated to be nonirritating and nonsensitizing, which may be based on a quantitative risk assessment or other accepted methodologies. The Panel also concluded that the data are insufficient to determine the safety of Polyaminopropyl Biguanide in products that may be incidentally inhaled.

Determination of Polyhexamethylene Biguanide Hydrochloride Using a Lactone-Rhodamine B-Based Fluorescence Optode.

A new determination method for polyhexamethylene biguanide hydrochloride (PHMB) using a lactone-rhodamine B (L-RB) based fluorescence optode has been developed. The optode membrane consists of 2-nitrophenyl octyl ether as a plasticizer, L-RB, and poly (vinyl chloride). The optode responds to tetrakis (4-fluorophenyl) borate, sodium salt (NaTPBF) in the µM range. The fluorescence intensity of the L-RB film for PHMB solution containing 20 µM NaTPBF decreased linearly as the concentration of the PHMB solution increased in the concentration range from 0 to 8.0 µM, which shows that PHMB with a concentration range of 0 to 8.0 µM is determined by the L-RB film optode. The concentration of PHMB in the contact lens detergents by the proposed method was in accord with its nominal concentration.

Albumin reduces the antibacterial efficacy of wound antiseptics against Staphylococcus aureus.

OBJECTIVE: The influence of proteins on the efficacy of antiseptic solutions has been rarely investigated even though exudate can contain high levels of protien. The aim of this study was to analyse the antibacterial efficacy of commonly used solutions in the presence of albumin protein. METHOD: Using Staphylococcus aureus in a standardised quantitative suspension assay, the antibacterial effects of poly (1-(2-oxo-1-pyrrolidinyl) ethylene)-iodine (PVP-I) and octenidin-dihydrochloride/phenoxyethanol (OCT/PE) were analysed in the presence of 0-3% bovine serum albumin (BSA). These were compared with previous results obtained with polyhexamethylene biguanide hydrochloride (PHMB). RESULTS: Presence of albumin caused a significant (p<0.001) decrease in antibacterial effect in the analysed solutions. The concentrations of albumin that provoked highly significant decreases in the bacterial reduction factors of the study agents were: 0.01875 % for PVP-I, followed by 0.75 % for OCT/PE. After addition of 3 % albumin, adequate antimicrobial effects were ensured for titrations to 5 % PVP-I and 8 % OCT/PE. As we could show before, it is not possible to titrate PHMB in order to assure adequate potency. CONCLUSION: This study demonstrates that albumin induces a significant decrease of the antibacterial potency of the analysed solutions.

Versatile synthesis of PHMB-stabilized silver nanoparticles and their significant stimulating effect on fodder beet (Beta vulgaris L.).

Silver nanoparticles (AgNPs) are well-known bactericidal agents. However, information about the influence of AgNPs on the morphometric parameters and biochemical status of most important agricultural crops is limited. The present study reports the influence of AgNPs stabilized with cationic polymer polyhexamethylene biguanide hydrochloride (PHMB) on growth, development, and biochemical status of fodder beet Beta vulgaris L. under laboratory and greenhouse conditions. PHMB-stabilized AgNPs were obtained via sodium borohydride reduction of silver nitrate in an aqueous solution. The average diameter of thus prepared AgNPs was 10 nm. It appears that the results of experiments with laboratory-grown beets in the nanosilver-containing medium, where germination of seeds and growth of roots were suppressed, do not correlate with the results of greenhouse experiments. The observed growth-stimulating action of PHMB-stabilized AgNPs can be explained by the change of activity of oxidases and, consequently, by the change of auxins amount in plant tissues. In beets grown in the presence of PHMB-stabilized AgNPs no negative deviations of biological parameters from normal values were registered. Furthermore, the SEM/EDS examination revealed no presence of silver in the tissues of the studied plants.