Antimicrobial Hydantoin-Containing Polyesters

Fabrication of N-halamine polyurethane films with excellent antibacterial properties

An N-halamine precursor, namely, 2-amino-5-(2-hydroxyethyl)-6-methylpyrimidin-4-one (AHM), was used as a chain extender in the preparation of a series of N-halamine polyurethane (PU) films, in order to also instill antibacterial properties. The mechanical properties, thermodynamic performance, and antimicrobial performance of the functionalized PU films were systematically studied. The results showed that the addition of AHM could improve the thermodynamic and mechanical properties of the developed PU films. Conducting tests in the presence of Escherichia coli and Staphylococcus aureus as the model microorganisms revealed that prior to chlorination the antibacterial properties of the chlorinated PU-AHM-Cl films improved significantly relative to the analogous films. The excellent antibacterial properties and the overall superior performance of the PU-AHM-Cl films allow their potential application in microbiological protection materials and related fields.

Cu-catalyzed N-3-Arylation of Hydantoins Using Diaryliodonium Salts

A general Cu-catalyzed, regioselective method for the N-3-arylation of hydantoins is described. The protocol utilizes aryl(trimethoxyphenyl)iodonium tosylate as the arylating agent in the presence of triethylamine and a catalytic amount of a simple Cu-salt. The method is compatible with structurally diverse hydantoins and operates well with neutral aryl groups or aryl groups bearing weakly donating/withdrawing elements. It is also applicable for the rapid diversification of pharmaceutically relevant hydantoins.

Surface Charge Switchable Supramolecular Nanocarriers for Nitric Oxide Synergistic Photodynamic Eradication of Biofilms

Biofilm has resulted in numerous obstinate clinical infections, posing severe threats to public health. It is urgent to develop original antibacterial strategies for eradicating biofilms. Herein, we develop a surface charge switchable supramolecular nanocarrier exhibiting pH-responsive penetration into an acidic biofilm for nitric oxide (NO) synergistic photodynamic eradication of the methicillin-resistant Staphylococcus aureus (MRSA) biofilm with negligible damage to healthy tissues under laser irradiation. Originally, by integrating the glutathione (GSH)-sensitive α-cyclodextrin (α-CD) conjugated nitric oxide (NO) prodrug (α-CD-NO) and chlorin e6 (Ce6) prodrug (α-CD-Ce6) into the pH-sensitive poly(ethylene glycol) (PEG) block polypeptide copolymer (PEG-(KLAKLAK)₂-DA) via host-guest interaction, the supramolecular nanocarrier α-CD-Ce6-NO-DA was finely prepared. The supramolecular nanocarrier shows complete surface charge reversal from negative charge at physiological pH (7.4) to positive charge at acidic biofilm pH (5.5), promoting efficient penetration into the biofilm. Once infiltrated into the biofilm, the nanocarrier exhibits rapid NO release triggered by the overexpressed GSH in the biofilm, which not only produces abundant NO for killing bacteria but also reduces the biofilm GSH level to improve photodynamic therapy (PDT) efficiency. On the other hand, NO can react with reactive oxygen species (ROS) to produce reactive nitrogen species (RNS), further improving the PDT efficiency. Due to the effective penetration into the biofilm and depletion of biofilm GSH, the surface charge switchable GSH-sensitive NO nanocarrier can greatly improve the PDT efficiency at a low photosensitizer dose and laser intensity and cause negligible side effect to healthy tissues. Considering the above advantages, the strategy developed in this work may offer great possibilities to fight against biofilm infections.

Photothermal Killing of Methicillin-Resistant Staphylococcus aureus by Bacteria-Targeted Polydopamine Nanoparticles with Nano-Localized Hyperpyrexia

Bacterial infections caused by antibiotic-resistant pathogens have become intractable problems to public health. Therefore, there is an imperious demand for developing new approaches to effectively kill antibiotic-resistant bacteria. In this work, we report a kind of bacteria-targeted polydopamine nanoparticle exhibiting great photothermal killing ability toward methicillin-resistant Staphylococcus aureus (MRSA) by nano-localized hyperpyrexia under low-power near-infrared (NIR) light irradiation. These bacteria-targeted nanoparticles (PDA-PEG-Van) are prepared by modifying polydopamine nanoparticles with thiol-poly(ethylene glycol) (mPEG-SH) and vancomycin (Van) molecules. The PEG shell endows the nanoparticles with excellent long-term circulation stability. Due to the multivalent hydrogen-bond interactions between vancomycin and the MRSA cell wall, the vancomycin-modified polydopamine nanoparticles can specifically target MRSA rather than mammalian cells. These bacteria-targeted nanoparticles are employed as a nano-localized heat source to kill MRSA via disrupting the bacterial cell wall and membrane under irradiation of low-power NIR light. More importantly, the surrounding healthy tissues suffer bare damage, owing to the absence of any targeting effect of PDA-PEG-Van toward mammalian cells and the low power of NIR light used in the therapeutic process. Given the above advantages, the bacteria-targeted polydopamine nanoparticles proposed in this work show tremendous potential to treat MRSA infections, because they can effectively limit localized heating in the infection sites to kill bacteria and cut down damage to healthy tissues.

Development of new hydantoin-based biocidal polymers with improved rechargeability and anti-microbial activity

Novel hydantoin based co-polymers containing both amide and imide positions for halogen capture with improved rechargeability and antibacterial activity were developed.

Surface-Adaptive Gold Nanoparticles with Effective Adherence and Enhanced Photothermal Ablation of Methicillin-Resistant Staphylococcus aureus Biofilm

Biofilms that contribute to the persistent bacterial infections pose serious threats to global public health, mainly due to their resistance to antibiotics penetration and escaping innate immune attacks by phagocytes. Here, we report a kind of surface-adaptive gold nanoparticles (AuNPs) exhibiting (1) a self-adaptive target to the acidic microenvironment of biofilm, (2) an enhanced photothermal ablation of methicillin-resistant Staphylococcus aureus (MRSA) biofilm under near-infrared (NIR) light irradiation, and (3) no damage to the healthy tissues around the biofilm. Originally, AuNPs were readily prepared by surface modification with pH-responsive mixed charged zwitterionic self-assembled monolayers consisting of weak electrolytic 11-mercaptoundecanoic acid (HS-C₁₀-COOH) and strong electrolytic (10-mercaptodecyl)trimethylammonium bromide (HS-C₁₀-N₄). The mixed charged zwitterion-modified AuNPs showed fast pH-responsive transition from negative charge to positive charge, which enabled the AuNPs to disperse well in healthy tissues (pH ∼7.4), while quickly presenting strong adherence to negatively charged bacteria surfaces in MRSA biofilm (pH ∼5.5). Simultaneous AuNP aggregation within the MRSA biofilm enhanced the photothermal ablation of MRSA biofilm under NIR light irradiation. The surrounding healthy tissues showed no damage because the dispersed AuNPs had no photothermal effect under NIR light. In view of the above advantages as well as the straightforward preparation, AuNPs developed in this work may find potential applications as a useful antibacterial agent in the areas of healthcare.

Hyperbranched polyesters as biodegradable and antibacterial additives

Herein, we present novel hyperbranched poly(amino-ester)s functionalized with quaternary ammonium salts.

Cytocompatible antibacterial fibrous membranes based on poly(3-hydroxybutyrate-co-4-hydroxybutyrate) and quaternarized N-halamine polymer

A novel polymeric N-halamine-containing quaternary ammonium salt (PHQS) was synthesized and used to make antibacterial electrospun fibrous membranes by blending with biodegradable poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P(3HB-4HB)).