Combatting Fungal Infections: Advances in Antifungal Polymeric Nanomaterials

Fungal pathogens cause over 6.5 million life-threatening systemic infections annually, with mortality rates ranging from 20 to 95%, even with medical intervention. The World Health Organization has recently emphasized the urgent need for new antifungal drugs. However, the range of effective antifungal agents remains limited and resistance is increasing. This Review explores the current landscape of fungal infections and antifungal drugs, focusing on synthetic polymeric nanomaterials like nanoparticles that enhance the physicochemical properties of existing drugs. Additionally, we examine intrinsically antifungal polymers that mimic naturally occurring peptides. Advances in polymer characterization and synthesis now allow precise design and screening for antifungal activity, biocompatibility, and drug interactions. These antifungal polymers represent a promising new class of drugs for combating fungal infections.

Smart Galactosidase-Responsive Antimicrobial Dendron: Towards More Biocompatible Membrane-Disruptive Agents

Antimicrobial resistance is a global healthcare challenge that urgently needs the development of new therapeutic agents. Antimicrobial peptides and mimics thereof are promising candidates but mostly suffer from inherent toxicity issues due to the non-selective binding of cationic groups with mammalian cells. To overcome this toxicity issue, this work herein reports the synthesis of a smart antimicrobial dendron with masked cationic groups (Gal-Dendron) that could be uncaged in the presence of β-galactosidase enzyme to form the activated Enz-Dendron and confer antimicrobial activity. Enz-Dendron show bacteriostatic activity toward Gram-negative (P. aeruginosa and E. coli) and Gram-positive (S. aureus) bacteria with minimum inhibitory concentration values of 96 µm and exerted its antimicrobial mechanism via a membrane disruption pathway, as indicated by inner and outer membrane permeabilization assays. Crucially, toxicity studies confirmed that the masked prodrug Gal-Dendron exhibited low hemolysis and is at least 2.4 times less toxic than the uncaged cationic Enz-Dendron, thus demonstrating the advantage of masking the cationic groups with responsive immolative linkers to overcome toxicity and selectivity issues. Overall, this study highlights the potential of designing new membrane-disruptive antimicrobial agents that are more biocompatible via the amine uncaging strategy.

Effect of Star Topology Versus Linear Polymers on Antifungal Activity and Mammalian Cell Toxicity

The global increase in invasive fungal infections and the emergence of drug-resistant strains demand the urgent development of novel antifungal drugs. In this context, synthetic polymers with diverse compositions, mimicking natural antimicrobial peptides, have shown promising potential for combating fungal infections. This study investigates how altering polymer end-groups and topology from linear to branched star-like structures affects their efficacy against Candida spp., including clinical isolates. Additionally, the polymers' biocompatibility is accessed with murine embryonic fibroblasts and red blood cells in vitro. Notably, a low-molecular weight star polymer outperforms both its linear polymeric counterparts and amphotericin B (AmpB) in terms of an improved therapeutic index and reduced haemolytic activity, despite a higher minimum inhibitory concentration against Candida albicans (C. albicans) SC5314 (16-32 µg mL-1 vs 1 µg mL-1 for AmpB). These findings demonstrate the potential of synthetic polymers with diverse topologies as promising candidates for antifungal applications.

Mimicking Charged Host-Defense Peptides to Tune the Antifungal Activity and Biocompatibility of Amphiphilic Polymers

Invasive fungal infections impose a substantial global health burden. They cause more than 1.5 million deaths annually and are insufficiently met by the currently approved antifungal drugs. Antifungal peptides are a promising alternative to existing antifungal drugs; however, they can be challenging to synthesize, and are often susceptible to proteases in vivo. Synthetic polymers which mimic the properties of natural antifungal peptides can circumvent these limitations. In this study, we developed a library of 29 amphiphilic polyacrylamides with different charged units, namely, amines, guanidinium, imidazole, and carboxylic acid groups, representative of the natural amino acids lysine, arginine, histidine, and glutamic acid. Ternary polymers incorporating primary ammonium (lysine-like) or imidazole (histidine-like) groups demonstrated superior activity against Candida albicans and biocompatibility with mammalian cells compared to the polymers containing the other charged groups. Furthermore, a combination of primary ammonium, imidazole, and guanidinium (arginine-like) within the same polymer outperformed the antifungal drug amphotericin B in terms of therapeutic index and exhibited fast C. albicans-killing activity. The most promising polymer compositions showed synergistic effects in combination with caspofungin and fluconazole against C. albicans and additionally demonstrated activity against other clinically relevant fungi. Collectively, these results indicate the strong potential of these easily producible polymers to be used as antifungals.

Synthesis and antibacterial properties of fluorinated biodegradable cationic polyesters

Antimicrobial peptide-mimicking antibacterial polymers represent a practical strategy to conquer the ever-growing threat of antimicrobial resistance. Herein, we report the syntheses and antibacterial performance of degradable amphiphilic cationic polyesters containing pendent quaternary ammonium motifs and hydrophobic alkyl or fluoroalkyl groups. These polyesters were conveniently prepared from poly(3-methylene-1,5-dioxepan-2-one) via highly efficient one-pot successive thiol-Michael addition reactions. The antibacterial activity of these polyesters against S. aureus and E. coli and their hemolytic activity toward red blood cells were evaluated; some of them showed moderate antibacterial activity and selectivity against Gram-positive S. aureus. The membrane disruption mechanism of these cationic polyesters was briefly explored by monitoring the bacteria killing kinetics and SEM observations. Moreover, the effects of cationic/hydrophobic ratio and the incorporation of fluoroalkyl groups on the antibacterial activity and selectivity of the polyesters were demonstrated.

Anionic Hyperbranched Amphiphilic Polyelectrolytes as Nanocarriers for Antimicrobial Proteins and Peptides

This manuscript presents the synthesis of hyperbranched amphiphilic poly (lauryl methacrylate-co-tert-butyl methacrylate-co-methacrylic acid), H-P(LMA-co-tBMA-co-MAA) copolymers via reversible addition fragmentation chain transfer (RAFT) copolymerization of tBMA and LMA, and their post-polymerization modification to anionic amphiphilic polyelectrolytes. The focus is on investigating whether the combination of the hydrophobic characters of LMA and tBMA segments, as well as the polyelectrolyte and hydrophilic properties of MAA segments, both distributed within a unique hyperbranched polymer chain topology, would result in intriguing, branched copolymers with the potential to be applied in nanomedicine. Therefore, we studied the self-assembly behavior of these copolymers in aqueous media, as well as their ability to form complexes with cationic proteins, namely lysozyme (LYZ) and polymyxin (PMX). Various physicochemical characterization techniques, including size exclusion chromatography (SEC) and proton nuclear magnetic resonance (1H-NMR), verified the molecular characteristics of these well-defined copolymers, whereas light scattering and fluorescence spectroscopy techniques revealed promising nanoparticle (NP) self- and co-assembly properties of the copolymers in aqueous media.

Macromolecular Design and Engineering of New Amphiphilic N-Vinylpyrrolidone Terpolymers for Biomedical Applications

New amphiphilic VP-(di)methacrylate terpolymers of different monomer compositions and topologies have been synthesized by radical polymerization in toluene without any growth regulator of polymer chains. Their structures and properties in solid state and water solution were studied by double-detector size-exclusion chromatography; IR-, 1H, and 13C NMR-spectroscopy; DLS, TEM, TG, and DSC methods. The composition of the VP-AlkMA-TEGDM monomer mixture has been established to regulate the topology of the resulting macromolecules. The studied terpolymers presented on TEM images as individual low-contrast particles and their conglomerates of various sizes with highly ordered regions; in general, they are amorphous structures. None of the terpolymers demonstrated cytotoxic effects for noncancerous Vero and tumor HeLa cells. Hydrophobic D-α-tocopherol (TP) was encapsulated in terpolymer nanoparticles (NPs), and its antioxidant activity was evaluated by ABTS (radical monocation 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid)) or DPPH (2,2'-diphenyl-1-picrylhydrazyl) methods. The reaction efficiency depends on the TP-NP type. The IC50 values for the decolorization reaction of ABTS•+ and DPPH inhibition in the presence of initial and encapsulated TP were obtained.

Electrostatic and Covalent Binding of an Antibacterial Polymer to Hydroxyapatite for Protection against Escherichia coli Colonization

Orthopedic-device-related infections are notorious for causing physical and psychological trauma to patients suffering from them. Traditional methods of treating these infections have relied heavily on antibiotics and are becoming ineffectual due to the rise of antibiotic-resistant bacteria. Mimics of antimicrobial peptides have emerged as exciting alternatives due to their favorable antibacterial properties and lack of propensity for generating resistant bacteria. In this study, the efficacy of an antibacterial polymer as a coating material for hydroxyapatite and glass surfaces, two materials with wide ranging application in orthopedics and the biomedical sciences, is demonstrated. Both physical and covalent modes of attachment of the polymer to these materials were explored. Polymer attachment to the material surfaces was confirmed via X-ray photoelectron spectroscopy and contact angle measurements. The modified surfaces exhibited significant antibacterial activity against the Gram-negative bacterium E. coli, and the activity was retained for a prolonged period on the surfaces of the covalently modified materials.

Synthetic Star Nanoengineered Antimicrobial Polymers as Antibiofilm Agents: Bacterial Membrane Disruption and Cell Aggregation

Antimicrobial resistance has become a worldwide issue, with multiresistant bacterial strains emerging at an alarming rate. Multivalent antimicrobial polymer architectures such as bottle brush or star polymers have shown great potential, as they could lead to enhanced binding and interaction with the bacterial cell membrane. In this study, a library of amphiphilic star copolymers and their linear copolymer equivalents, based on acrylamide monomers, were synthesized via RAFT polymerization. Their monomer distribution and molecular weight were varied. Subsequently, their antimicrobial activity toward a Gram-negative bacterium (Pseudomonas aeruginosa PA14) and a Gram-positive bacterium (Staphylococcus aureus USA300) and their hemocompatibility were investigated. The statistical star copolymer, S-SP25, showed an improved antimicrobial activity compared to its linear equivalent againstP. aeruginosaPA14. The star architecture enhanced its antimicrobial activity, causing bacterial cell aggregation, as revealed via electron microscopy. However, it also induced increased red blood cell aggregation compared to its linear equivalents. Changing/shifting the position of the cationic block to the core of the structure prevents the cell aggregation effect while maintaining a potent antimicrobial activity for the smallest star copolymer. Finally, this compound showed antibiofilm properties against a robust in vitro biofilm model.

Hyperbranched Copolymers of Methacrylic Acid and Lauryl Methacrylate H-P(MAA-co-LMA): Synthetic Aspects and Interactions with Biorelevant Compounds

The synthesis of novel copolymers using one-step reversible addition-fragmentation chain transfer (RAFT) copolymerization of biocompatible methacrylic acid (MAA), lauryl methacrylate (LMA), and difunctional ethylene glycol dimethacrylate (EGDMA) as a branching agent is reported. The obtained amphiphilic hyperbranched H-P(MAA-co-LMA) copolymers are molecularly characterized by size exclusion chromatography (SEC), FTIR, and ¹H-NMR spectroscopy, and subsequently investigated in terms of their self-assembly behavior in aqueous media. The formation of nanoaggregates of varying size, mass, and homogeneity, depending on the copolymer composition and solution conditions such as concentration or pH variation, is demonstrated by light scattering and spectroscopic techniques. Furthermore, drug encapsulation properties are studied by incorporating the low bioavailability drug, curcumin, in the nano-aggregate hydrophobic domains, which can also act as a bioimaging agent. The interaction of polyelectrolyte MAA units with model proteins is described to examine protein complexation capacity relevant to enzyme immobilization strategies, as well as explore copolymer self-assembly in simulated physiological media. The results confirm that these copolymer nanosystems could provide competent biocarriers for imaging and drug or protein delivery/enzyme immobilization applications.

Design of Quorum Sensing Inhibitor-Polymer Conjugates to Penetrate Pseudomonas aeruginosa Biofilms

Antimicrobial resistance (AMR) is a global threat to public health with a forecast of a negative financial impact of one trillion dollars per annum, hence novel therapeutics are urgently needed. The resistance of many bacteria against current drugs is further augmented by the ability of these microbes to form biofilms where cells are encased in a slimy extracellular matrix and either adhered to a surface or forming cell aggregates. Biofilms form physiochemical barriers against the penetration of treatments such as small molecule antibacterials, rendering most treatments ineffective. Pseudomonas aeruginosa, a priority pathogen of immediate concern, controls biofilm formation through multiple layers of gene regulation pathways including quorum sensing (QS), a cell-to-cell signaling system. We have recently reported a series of inhibitors of the PqsR QS regulator from this organism that can potentiate the action of antibiotics. However, these QS inhibitors (QSIs) have shown modest effects on biofilms in contrast with planktonic cultures due to poor penetration through the biofilm matrix. To enhance the delivery of the inhibitors, a small library of polymers was designed as carriers of a specific QSI, with variations in the side chains to introduce either positively charged or neutral moieties to aid penetration into and through the P. aeruginosa biofilm. The synthesized polymers were evaluated in a series of assays to establish their effects on the inhibition of the Pqs QS system in P. aeruginosa, the levels of inhibitor release from polymers, and their impact on biofilm formation. A selected cationic polymer-QSI conjugate was found to penetrate effectively through biofilm layers and to release the QSI. When used in combination with ciprofloxacin, it enhanced the biofilm antimicrobial activity of this antibiotic compared to free QSI and ciprofloxacin under the same conditions.

Mechanically robust and highly bactericidal macroporous polymeric gels based on quaternized N,N-(dimethylamino)ethyl methacrylate possessing varying alkyl chain lengths

In this paper, macroporous antimicrobial polymeric gels (MAPGs) functionalized with active quaternary ammonium cations attached to varying hydrocarbon chain lengths have been fabricated. Apart from the change in the alkyl chain length attached to the quaternary ammonium cation, the amount of crosslinker was also varied during the fabrication of the macroporous gels. The prepared gels were characterized using Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, field emission scanning electron microscopy (FE-SEM) and swelling studies. In addition, the mechanical properties of the fabricated macroporous gels were studied using compression and tensile testing. The antimicrobial activity of the gels has been determined for Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa) as well as Gram-positive bacteria (Bacillus subtilis, Staphylococcus aureus). Antimicrobial activity, as well as the mechanical properties of the macroporous gels, was found to be influenced by the alkyl chain length attached to the quaternary ammonium cations as well as by the amount of crosslinker used for the fabrication of the gel. In addition, on increasing the alkyl chain length from C4 (butyl) to C8 (octyl), the effectiveness of the polymeric gels increased. It was observed that the gels derived using a tertiary amine (NMe₂) containing monomer showed relatively low antimicrobial activity as compared to the gels obtained using quaternized monomers (C4 (butyl), C6 (hexyl), and C8 (octyl)). The gels based on the quaternized C8 monomer displayed the highest antimicrobial activity and mechanical stability as compared to the gels based on the C4 and C6 monomers.

Glycopolymers for Antibacterial and Antiviral Applications

Diseases induced by bacterial and viral infections are common occurrences in our daily life, and the main prevention and treatment strategies are vaccination and taking antibacterial/antiviral drugs. However, vaccines can only be used for specific viral infections, and the abuse of antibacterial/antiviral drugs will create multi-drug-resistant bacteria and viruses. Therefore, it is necessary to develop more targeted prevention and treatment methods against bacteria and viruses. Proteins on the surface of bacteria and viruses can specifically bind to sugar, so glycopolymers can be used as potential antibacterial and antiviral drugs. In this review, the research of glycopolymers for bacterial/viral detection/inhibition and antibacterial/antiviral applications in recent years are summarized.

Shape Matters: Highly Selective Antimicrobial Bottle Brush Copolymers via a One-Pot RAFT Polymerization Approach

The one-pot synthesis of antimicrobial bottle brush copolymers is presented. Reversible addition-fragmentation chain-transfer (RAFT) polymerization is used for the production of the polymeric backbone, as well as for the grafts, which were installed using a grafting-from approach. A combination of N-isopropyl acrylamide and a Boc-protected primary amine-containing acrylamide was used in different compositions. After deprotection, polymers featuring different charge densities were obtained in both linear and bottle brush topologies. Antimicrobial activity was tested against three clinically relevant bacterial strains, and growth inhibition was significantly increased for bottle brush copolymers. Blood compatibility investigations revealed strong hemagglutination for linear copolymers and pronounced hemolysis for bottle brush copolymers. However, one bottle brush copolymer with a 50% charge density revealed strong antibacterial activity and negligible in vitro blood toxicity (regarding hemolysis and hemagglutination tests) resulting in selectivity values as high as 320. Membrane models were used to probe the mechanism of shown polymers that was found to be based on membrane disruption. The trends from bioassays are accurately reflected in model systems indicating that differences in lipid composition might be responsible for selectivity. However, bottle brush copolymers were found to possess increased cytotoxicity against human embryonic kidney (HEK) cells compared with linear analogues. The introduced synthetic platform enables screening of further, previously inaccessible parameters associated with the bottle brush topology, paving the way to further improve their activity profiles.

Polymers showing intrinsic antimicrobial activity

Pathogenic microorganisms are considered to a major threat to human health, impinging on multiple sectors including hospitals, dentistry, food storage and packaging, and water contamination. Due to the increasing levels of antimicrobial resistance shown by pathogens, often caused by long-term abuse or overuse of traditional antimicrobial drugs, new approaches and solutions are necessary. In this area, antimicrobial polymers are a viable solution to combat a variety of pathogens in a number of contexts. Indeed, polymers with intrinsic antimicrobial activities have long been an intriguing research area, in part, due to their widespread natural abundance in materials such as chitin, chitosan, carrageen, pectin, and the fact that they can be tethered to surfaces without losing their antimicrobial activities. In addition, since the discovery of the strong antimicrobial activity of some synthetic polymers, much work has focused on revealing the most effective structural elements that give rise to optimal antimicrobial properties. This has often been synthesis targeted, with the generation of either new polymers or the modification of natural antimicrobial polymers with the addition of antimicrobial enhancing modalities such as quaternary ammonium or guanidinium groups. In this review, the growing number of polymers showing intrinsic antimicrobial properties from the past decade are highlighted in terms of synthesis; often based on post-synthesis modification and their utilization. This includes as surface coatings, for example on medical devices, such as intravascular catheters, orthopaedic implants and contact lenses, or directly as antibacterial agents (specifically as eye drops). Surface functionalisation with inherently antimicrobial polymers is highlighted and has been achieved via various techniques, including surface-bound initiators allowing RAFT or ATRP surface-based polymerization, or via physical immobilization such as by layer-by-layer techniques. This article also covers the mechanistic modes of action of intrinsic antimicrobial polymers against bacteria, viruses, or fungi.

Two plus One: Combination Therapy Tri-systems Involving Two Membrane-Disrupting Antimicrobial Macromolecules and Antibiotics

The escalating issue of multidrug-resistant (MDR) bacteria indicates the urgent need for new and effective strategies to combat this global health challenge. Here, we describe a new combinatorial approach that can be put forward for experimental therapy application against MDR bacteria. Specifically, we have developed a tri-system that includes the coadministration of two different membrane-disrupting-type antimicrobial agents─a synthetic antimicrobial polymer P and an antimicrobial peptide (AMP) colistin methanesulfonate (Col)─in conjunction with an antibiotic [doxycycline (Dox), rifampicin (Rif), or azithromycin (Azi)]. Traditionally, the administration of membrane-disrupting antimicrobial agents causes toxicity, but, in comparison, we demonstrated synergy and biocompatibility using this combinatorial approach. Checkerboard assays showed the occurrence of synergistic interactions in Col-Dox-P, Col-Rif-P, and Col-Azi-P tri-systems against wild-type and MDR Pseudomonas aeruginosa, with the Col-Dox-P system being the most effective. The ability to synergize thus enables the use of a lower dosage in combinations compared to the standalone agents. The tri-systems not only demonstrated bacteriostatic activity but were also bactericidal. For example, the Col-Dox-P system (at 8, 4, and 8 μg mL^-1, respectively) and the Col-Rif-P system (at 4, 8, and 16 μg mL^-1, respectively) were able to kill >99.999% of planktonic P. aeruginosa cells within 3 h of treatment. More importantly, an improvement of the therapeutic/selectivity index was achieved via combination therapy. Taking the Col-Dox-P system as an example, its biocompatibility with murine embryonic fibroblast cells was found to be comparable to that of polymer P alone despite the synergistic enhancement in antimicrobial activity of the combination. This resulted in a significant increase in selectivity by 16-fold for the Col-Dox-P combination system compared to P alone. Furthermore, the broad applicability of this tri-system strategy was demonstrated via the successful application of the AMP melittin in place of Col or P. Overall, this study sheds new insights on the application of membrane-disrupting antimicrobial agents in combination therapy and their potential for safer clinical use. Additionally, the information gathered in this study could inform the development of future combination therapy systems involving the simultaneous employment of multiple AMPs with antibiotics.

Antimicrobial Polymers of Linear and Bottlebrush Architecture: Probing the Membrane Interaction and Physicochemical Properties

Polymeric antimicrobial peptide mimics are a promising alternative for the future management of the daunting problems associated with antimicrobial resistance. However, the development of successful antimicrobial polymers (APs) requires careful control of factors such as amphiphilic balance, molecular weight, dispersity, sequence, and architecture. While most of the earlier developed APs focus on random linear copolymers, the development of APs with advanced architectures proves to be more potent. It is recently developed multivalent bottlebrush APs with improved antibacterial and hemocompatibility profiles, outperforming their linear counterparts. Understanding the rationale behind the outstanding biological activity of these newly developed antimicrobials is vital to further improving their performance. This work investigates the physicochemical properties governing the differences in activity between linear and bottlebrush architectures using various spectroscopic and microscopic techniques. Linear copolymers are more solvated, thermo-responsive, and possess facial amphiphilicity resulting in random aggregations when interacting with liposomes mimicking Escheria coli membranes. The bottlebrush copolymers adopt a more stable secondary conformation in aqueous solution in comparison to linear copolymers, conferring rapid and more specific binding mechanism to membranes. The advantageous physicochemical properties of the bottlebrush topology seem to be a determinant factor in the activity of these promising APs.

Antimicrobial Peptides and Macromolecules for Combating Microbial Infections: From Agents to Interfaces

Bacterial resistance caused by the overuse of antibiotics and the shelter of biofilms has evolved into a global health crisis, which drives researchers to continuously explore antimicrobial molecules and strategies to fight against drug-resistant bacteria and biofilm-associated infections. Cationic antimicrobial peptides (AMPs) are considered to be a category of potential alternative for antibiotics owing to their excellent bactericidal potency and lesser likelihood of inducing drug resistance through their distinctive antimicrobial mechanisms. In this review, the hitherto reported plentiful action modes of AMPs are systematically classified into 15 types and three categories (membrane destructive, nondestructive membrane disturbance, and intracellular targeting mechanisms). Besides natural AMPs, cationic polypeptides, synthetic polymers, and biopolymers enable to achieve tunable antimicrobial properties by optimizing their structures. Subsequently, the applications of these cationic antimicrobial agents at the biointerface as contact-active surface coatings and multifunctional wound dressings are also emphasized here. At last, we provide our perspectives on the development of clinically significant cationic antimicrobials and related challenges in the translation of these materials.

Nonionic nontoxic antimicrobial polymers: indole-grafted poly(vinyl alcohol) with pendant alkyl or ether groups

A series of new nonionic antimicrobial polymers with a biodegradable polyvinyl alcohol (PVA) backbone grafted with indole units and different hydrophobic alkyl or ether groups were synthesized by facile esterification.

Main-Chain Sulfonium-Containing Homopolymers with Negligible Hemolytic Toxicity for Eradication of Bacterial and Fungal Biofilms

Antimicrobials against planktonic cells and established biofilms at low doses are in increasing demand to tackle antibiotic-resistant biofilm infections. As a promising alternative to antibiotics, cationic polymers can effectively kill planktonic microbes but usually require high concentrations to eradicate the established biofilms. Herein, we developed a series of sulfonium-based homopolymers with cationic sulfoniums and alkane spacers in the main chain. These polysulfoniums presented effective activity against planktonic fungi (Candida albicans) and bacteria (Escherichia coli and Staphylococcus aureus) with minimum inhibition concentrations (MICs) of 0.5-32 μg/mL, and the optimal composition can provide an 80-90% reduction in biofilm mass and >99% killing of Candida albicans and Escherichia coli cells in 3-day mature biofilms at 2 × MIC as well as steadily low hemolytic toxicity. The influence of amphiphilicity and charge density of polysulfonium homopolymers on their antimicrobial activity against planktonic microbes and mature biofilms was investigated to provide insights for effective antimicrobial polymer design.

Tug-of-War between Covalent Binding and Electrostatic Interaction Effectively Killing E. coli without Detectable Resistance

Antimicrobial resistance in Gram-negative bacteria has become one of the leading causes of morbidity and mortality and a serious worldwide public health concern due to the fact that Gram-negative bacteria have an additional outer membrane protecting them from an unwanted compound invading. It is still very difficult for antimicrobials to reach intracellular targets and very challenging to treat Gram-negative bacteria with the current strategies. Here, we found that (o-(bromomethyl)phenyl)boronic acid was incorporated into poly((2-N,N-diethyl)aminoethyl acrylate) (PDEA), forming a copolymer (poly(o-B_n-DEA)) having both phenylboronic acid (B) and ((2-N,N-diethyl)amino) (DEA) units. Poly(o-B_n-DEA) exhibits very strong intramolecular B-N coordination, which could highly promote the covalent binding of phenylboronic acid with lipopolysaccharide (LPS) on the outer membrane of E. coli and lodge poly(o-B_n-DEA) on the LPS layer on the surface of E. coli. Meanwhile, the strong electrostatic interaction between poly(o-B_n-DEA) and the negatively charged lipid preferred tugging the poly(o-B_n-DEA) into the lipid bilayer of E. coli. The combating interactions between covalent binding and electrostatic interaction form a tug-of-war action, which could trigger the lysis of the outer membrane, thereby killing Gram-negative E. coli effectively without detectable resistance.

Photo-Enhanced Antimicrobial Activity of Polymers Containing an Embedded Photosensitiser

This work presents the synthesis of a novel photosensitive acrylate monomer for use as both a self-catalyst in the photoinduced electron/energy transfer-reversible addition fragmentation chain transfer (PET-RAFT) polymerisation process and a photosensitiser (PS) for antibacterial applications. Hydrophilic, cationic, and antimicrobial formulations are explored to compare the antibacterial effects between charged and non-charged polymers. Covalent attachment of the catalyst to well-defined linear polymer chains has no effect on polymerisation control or singlet oxygen generation. The addition of the PS to polymers provides activity against S. aureus for all polymer formulations, resulting in up to a 99.99999 % killing efficacy in 30 min. Antimicrobial peptide mimetic polymers previously active against P. aeruginosa, but not S. aureus, gain significant bactericidal activity against S. aureus through the inclusion of PS groups, with 99.998 % killing efficiency after 30 min incubation with light. Thus, a broader spectrum of antimicrobial activity is achieved using two distinct mechanisms of bactericidal activity via the incorporation of a photosensitiser monomer into an antimicrobial polymer.

Possibility for double optimization of siRNA intracellular delivery efficiency and antibacterial activity: Structure screening of pH-sensitive triblock amphiphilic polycation micelles

Optimal combination of hydrophobic-hydrophilic balance, proton buffering and electrostatic interaction is the key issue for designing polycations as efficient gene vectors and antibacterial agents. Herein, we screened a series of pH-sensitive quaternary ammonium-based amphiphilic triblock copolymers, mPEG_2k-P(DPA_a/DMA_b)-PQA_c (TDDE-x), which had different pKa values and proton buffering capacities. Significantly, we found that both the highest siRNA intracellular delivery efficiency and the strongest antibacterial capacity occurred on TDDE-3 micelles with the segment structure of mPEG_2k-P(DPA₅₀/DMA₅₆)-PQA₅₅. The TDDE-3/siRNA complex achieved 67% silencing efficiency on H9C2 cells (N/P = 5, 50 nM siRNA), higher than the advanced commercial transfection reagents RNAiMAX (58%) and Lipo2000 (30%). Moreover, TDDE-3 micelles showed quite low MICs of 32 μg/mL and 8 μg/mL against E. coli and S. aureus, respectively. Further studies on the structure-function relationship indicated that TDDE-3 micelles could mediate robust endosome escape and siRNA cytosolic release, and strong bacterial cell membrane-destabilizing function. Undoubtedly, this work reveals the possibility for double optimization of siRNA intracellular delivery efficiency and antibacterial activity of amphiphilic polycations by reasonable structure design, which is significant for low-cost development and clinical translation of efficient multifunctional polycations.

Cationic Lignin-Based Hyperbranched Polymers to Circumvent Drug Resistance in Pseudomonas Keratitis

The rise of antimicrobial-resistant bacteria strains has been a global public health concern due to their ability to cause increased patient morbidity and a greater burden on the healthcare system. As one of the potential solutions to overcome such bacterial infections, hyperbranched copolymers with cationic charges were developed. These copolymers were assessed for their antimicrobial efficacy and their bactericidal mechanisms. They were found to be potent against mobile colistin-resistant 1 strains, which was significant as colistin is known to be the last-resort antibiotic against Gram-negative bacteria. Furthermore, there was no sign of mutational resistance developed by E. Coli ATCC 25922 and MCR 1+ E. Coli against the copolymer even up to 20 passages. The ability to evade inducing resistance would provide invaluable insights for future antibiotic development. Our studies suggest that the bactericidal efficacy comes from the ability to target the outer membrane efficaciously. In vivo study using a Pseudomonas keratitis model showed that the copolymer was compatible with the eye and further supported that the copolymer treatment was effective for complete bacteria elimination.

The function of peptide-mimetic anionic groups and salt bridges in the antimicrobial activity and conformation of cationic amphiphilic copolymers

Herein we report the synthesis of ternary statistical methacrylate copolymers comprising cationic ammonium (amino-ethyl methacrylate: AEMA), carboxylic acid (propanoic acid methacrylate: PAMA) and hydrophobic (ethyl methacrylate: EMA) side chain monomers, to study the functional role of anionic groups on their antimicrobial and hemolytic activities as well as the conformation of polymer chains. The hydrophobic monomer EMA was maintained at 40 mol% in all the polymers, with different percentages of cationic ammonium (AEMA) and anionic carboxylate (PAMA) side chains, resulting in different total net charge for the polymers. The antimicrobial and hemolytic activities of the copolymer were determined by the net charge of +3 or larger, suggesting that there was no distinct effect of the anionic carboxylate groups on the antimicrobial and hemolytic activities of the copolymers. However, the pH titration and atomic molecular dynamics simulations suggest that anionic groups may play a strong role in controlling the polymer conformation. This was achieved via formation of salt bridges between cationic and anionic groups, transiently crosslinking the polymer chain allowing dynamic switching between compact and extended conformations. These results suggest that inclusion of functional groups in general, other than the canonical hydrophobic and cationic groups in antimicrobial agents, may have broader implications in acquiring functional structures required for adequate antimicrobial activity. In order to explain the implications, we propose a molecular model in which formation of intra-chain, transient salt bridges, due to the presence of both anionic and cationic groups along the polymer, may function as "adhesives" which facilitate compact packing of the polymer chain to enable functional group interaction but without rigidly locking down the overall polymer structure, which may adversely affect their functional roles.

Rational Design of an Antifungal Polyacrylamide Library with Reduced Host-Cell Toxicity

Life-threatening invasive fungal infections represent an urgent threat to human health worldwide. The limited set of antifungal drugs has critical constraints such as resistance development and/or adverse side effects. One approach to overcome these limitations is to mimic naturally occurring antifungal peptides called defensins. Inspired by their advantageous amphiphilic properties, a library of 35 synthetic, linear, ternary polyacrylamides was prepared by controlled/living radical polymerization. The effect of the degree of polymerization (20, 40, and 100) and varying hydrophobic functionalities (branched, linear, cyclic, or aromatic differing in their number of carbons) on their antifungal activity was investigated. Short copolymers with a calculated log P of ∼1.5 revealed optimal activity against the major human fungal pathogen Candida albicans and other pathogenic fungal species with limited toxicity to mammalian host cells (red blood cells and fibroblasts). Remarkably, selected copolymers outperformed the commercial antifungal drug amphotericin B, with respect to the therapeutic index, highlighting their potential as novel antifungal compounds.

Antimicrobial PEGtides: A Modular Poly(ethylene glycol)-Based Peptidomimetic Approach to Combat Bacteria

Despite their high potency, the widespread implementation of natural antimicrobial peptides is still challenging due to their low scalability and high hemolytic activities. Herein, we address these issues by employing a modular approach to mimic the key amino acid residues present in antimicrobial peptides, such as lysine, leucine, and serine, but on the highly biocompatible poly(ethylene glycol) (PEG) backbone. A series of these PEG-based peptides (PEGtides) were developed using functional epoxide monomers, corresponding to each key amino acid, with several possessing highly potent bactericidal activities and controlled selectivities, with respect to their hemolytic behavior. The critical role of the composition and the structure of the PEGtides in their selectivities was further supported by coarse-grained molecular dynamic simulations. This modular approach is anticipated to provide the design principles necessary for the future development of antimicrobial polymers.

Polymeric antibacterial materials: design, platforms and applications

Over the past decades, the morbidity and mortality caused by pathogen invasion remain stubbornly high even though medical care has increasingly improved worldwide. Besides, impacted by the ever-growing multidrug-resistant bacterial strains, the crisis owing to the abuse and misuse of antibiotics has been further exacerbated. Among the wide range of antibacterial strategies, polymeric antibacterial materials with diversified synthetic strategies exhibit unique advantages (e.g., their flexible structural design, processability and recyclability, tuneable platform construction, and safety) for extensive antibacterial fields as compared to low molecular weight organic or inorganic antibacterial materials. In this review, polymeric antibacterial materials are summarized in terms of four structure styles and the most representative material platforms to achieve specific antibacterial applications. The superiority and defects exhibited by various polymeric antibacterial materials are elucidated, and the design of various platforms to elevate their efficacy is also described. Moreover, the application scope of polymeric antibacterial materials is summarized with regard to tissue engineering, personal protection, and environmental security. In the last section, the subsequent challenges and direction of polymeric antibacterial materials are discussed. It is highly expected that this critical review will present an insight into the prospective development of antibacterial functional materials.

Combating drug-resistant bacterial infection using biodegradable nanoparticles assembled from comb-like polycarbonates grafted with amphiphilic polyquaternium

Bacterial infection is a serious clinical threat. The misuse of antibiotics has already resulted in the emergence of antibiotic-resistant strains of pathogenic bacteria. Efficient membrane-destructive antibacterial agents are considered as an alternative, promising solution against bacterial infection. Herein, we prepared a new type of comb-like cationic, polyethylene glycol (PEG) block polycarbonates with polyquaternium arms (G-CgQAs). The amphiphilic G-CgQAs could self-assemble into about 60 nm sized nanoparticles (NPs) with positive charges (20~30 mV). G-CgQA-3 NPs with an appropriate hydrophobic-hydrophilic balance in the polyquaternium arms showed antibacterial activity against Gram-negative, Gram-positive, and drug-resistant strains at low concentrations (MIC 64-128 μg mL-1) and low hemolysis (HC50 > 2000 μg mL-1). In vivo anti-infection tests indicated G-CgQA-3 NPs could highly inhibit the growth of vancomycin-resistant bacteria by spraying on wounds. Collectively, G-CgQA NPs hold great promise for the prevention of infection, serving as new antibacterial agents. This study also highlights the significance of a hydrophobic block in positive polyquaternium arms to facilitate the antibacterial activity of cationic, quaternized polymers. The design of comb-like amphiphilic cationic polycarbonates provides a new method for manufacturing antibacterial nano-agents.

Releasable antimicrobial polymer-silk coatings for combating multidrug-resistant bacteria

Controlled release of synthetic cationic antimicrobial polymers from silk-based coating for preventing bacterial biofilm formation on the surface and for killing planktonic bacteria cells.

State-of-the-art polymeric nanoparticles as promising therapeutic tools against human bacterial infections

Infectious diseases kill over 17 million people a year, among which bacterial infections stand out. From all the bacterial infections, tuberculosis, diarrhoea, meningitis, pneumonia, sexual transmission diseases and nosocomial infections are the most severe bacterial infections, which affect millions of people worldwide. Moreover, the indiscriminate use of antibiotic drugs in the last decades has triggered an increasing multiple resistance towards these drugs, which represent a serious global socioeconomic and public health risk. It is estimated that 33,000 and 35,000 people die yearly in Europe and the United States, respectively, as a direct result of antimicrobial resistance. For all these reasons, there is an emerging need to find novel alternatives to overcome these issues and reduced the morbidity and mortality associated to bacterial infectious diseases. In that sense, nanotechnological approaches, especially smart polymeric nanoparticles, has wrought a revolution in this field, providing an innovative therapeutic alternative able to improve the limitations encountered in available treatments and capable to be effective by theirselves. In this review, we examine the current status of most dangerous human infections, together with an in-depth discussion of the role of nanomedicine to overcome the current disadvantages, and specifically the most recent and innovative studies involving polymeric nanoparticles against most common bacterial infections of the human body.

Effects of Glycyrrhizin on Multi-Drug Resistant Pseudomonas aeruginosa

The effects of glycyrrhizin (GLY) on multi-drug resistant (MDR) systemic (MDR9) vs. ocular (B1045) Pseudomonas aeruginosa clinical isolates were determined. Proteomes of each isolate with/without GLY treatment were profiled using liquid chromatography mass spectrometry (LC-MS/MS). The effect of GLY on adherence of MDR isolates to immortalized human (HCET) and mouse (MCEC) corneal epithelial cells, and biofilm and dispersal was tested. Both isolates were treated with GLY (0.25 minimum inhibitory concentration (MIC), 10 mg/mL for MDR9 and 3.75 mg/mL for B1045) and subjected to proteomic analysis. MDR9 had a greater response to GLY (51% of identified proteins affected vs. <1% in B1045). In MDR9 vs. controls, GLY decreased the abundance of proteins for: antibiotic resistance, biofilm formation, and type III secretion. Further, antibiotic resistance and type III secretion proteins had higher control abundances in MDR9 vs. B1045. GLY (5 and 10 mg/mL) significantly reduced binding of both isolates to MCEC, and B1045 to HCET. MDR9 binding to HCET was only reduced at 10 mg/mL GLY. GLY (5 and 10 mg/mL) enhanced dispersal for both isolates, at early (6.5 h) but not later times (24–72 h). This study provides evidence that GLY has a greater effect on the proteome of MDR9 vs. B1045, yet it was equally effective at disrupting adherence and early biofilm dispersal.

Impact of Multivalence and Self-Assembly in the Design of Polymeric Antimicrobial Peptide Mimics

Antimicrobial resistance is an increasingly serious challenge for public health and could result in dramatic negative consequences for the health care sector during the next decades. To solve this problem, antibacterial materials that are unsusceptible toward the development of bacterial resistance are a promising branch of research. In this work, a new type of polymeric antimicrobial peptide mimic featuring a bottlebrush architecture is developed, using a combination of reversible addition-fragmentation chain transfer (RAFT) polymerization and ring-opening metathesis polymerization (ROMP). This approach enables multivalent presentation of antimicrobial subunits resulting in improved bioactivity and an increased hemocompatibility, boosting the selectivity of these materials for bacterial cells. Direct probing of membrane integrity of treated bacteria revealed highly potent membrane disruption caused by bottlebrush copolymers. Multivalent bottlebrush copolymers clearly outperformed their linear equivalents regarding bioactivity and selectivity. The effect of segmentation of cationic and hydrophobic subunits within bottle brushes was probed using heterograft copolymers. These materials were found to self-assemble under physiological conditions, which reduced their antibacterial activity, highlighting the importance of precise structural control for such applications. To the best of our knowledge, this is the first example to demonstrate the positive impact of multivalence, generated by a bottlebrush topology in polymeric antimicrobial peptide mimics, making these polymers a highly promising material platform for the design of new bactericidal systems.

Complex polymer architectures through free-radical polymerization of multivinyl monomers

The construction of complex polymer architectures with well-defined topology, composition and functionality has been extensively explored as the molecular basis for the development of modern polymer materials. The unique reaction kinetics of free-radical polymerization leads to the concurrent formation of crosslinks between polymer chains and rings within an individual chain and, thus, free-radical (co)polymerization of multivinyl monomers provides a facile method to manipulate chain topology and functionality. Regulating the relative contribution of these intermolecular and intramolecular chain-propagation reactions is the key to the construction of architecturally complex polymers. This can be achieved through the design of new monomers or by spatially or kinetically controlling crosslinking reactions. These mechanisms enable the synthesis of various polymer architectures, including linear, cyclized, branched and star polymer chains, as well as crosslinked networks. In this Review, we highlight some of the contemporary experimental strategies to prepare complex polymer architectures using radical polymerization of multivinyl monomers. We also examine the recent development of characterization techniques for sub-chain connections in such complex macromolecules. Finally, we discuss how these crosslinking reactions have been engineered to generate advanced polymer materials for use in a variety of biomedical applications.

Enzyme-Responsive Ag Nanoparticle Assemblies in Targeting Antibacterial against Methicillin-Resistant Staphylococcus Aureus

The abuse of antibiotics resulted in the emergence of antibiotics-resistant bacteria, which has raised a great social concern together with the impetus to develop effective antibacterial materials. Herein, the synthesis of biocompatible enzyme-responsive Ag nanoparticle assemblies (ANAs) and their application in the high-efficiency targeted antimicrobial treatment of methicillin-resistant Staphylococcus aureus (MRSA) have been demonstrated. The ANAs could collapse and undergo stable/collapsed transition on approaching MRSA because of the serine protease-like B enzyme proteins (SplB)-triggered decomposition of the branched copolymers which have been employed as the macrotemplate in the synthesis of responsive ANAs. This transition contributed greatly to the high targeting affinity and efficiency of ANAs to MRSA. The minimum inhibitory concentration and minimum bactericidal concentration against MRSA were 2.0 and 32.0 μg mL^-1, respectively. Skin wound healing experiments confirmed that the responsive ANAs could serve as an effective wound dressing to accelerate the healing of MRSA infection.

High-Throughput Preparation of Antibacterial Polymers from Natural Product Derivatives via the Hantzsch Reaction

The Hantzsch and free-radical polymerization reactions were combined in a one-pot high-throughput (HTP) system to simultaneously prepare 30 unique polymers in parallel. Six aldehydes derived from natural products were used as the starting materials to rapidly prepare the library of 30 poly(1,4-dihydropyridines). From this library, HTP evaluation methods led to the identification of an antibacterial polymer. Mechanistic studies revealed that the dihydropyridine group in the polymer side-chain structure plays an important role in resisting bacterial attachment to the polymer surface, thus leading to the antibacterial function of this polymer. This research demonstrates the value of multicomponent reactions (MCRs) in interdisciplinary fields by discovering functional polymers for possible practical applications. It also provides insights to further developing new functional polymers using MCRs and HTP methods with important implications in organic chemistry, polymer chemistry, and materials science.

Tunable nanostructures by directional assembly of donor–acceptor supramolecular copolymers and antibacterial activity

This manuscript reports supramolecular copolymerization of amphiphilic donor (D) and acceptor (A) units and their antibacterial activity.

Improving the antimicrobial efficacy against resistant Staphylococcus aureus by a combined use of conjugated oligoelectrolytes

Two membrane-intercalating conjugated oligoelectrolytes (COEs), namely COE-D8 and COE-S6, were combined to achieve enhanced antimicrobial efficacy. COE-D8 has a shorter molecular length than COE-S6 and is typical of effective antimicrobial COE molecules, presumably due to its prominent membrane disrupting function. In contrast, COE-D6 exhibits lower efficacy against bacteria and lower toxicity toward mammalian cells. Surprisingly, after supplementing 8 μM COE-S6, the minimum inhibitory concentration (MIC) of COE-D8 against methicillin-resistant Staphylococcus aureus (MRSA) was improved 8-fold, from 0.5 μM to 0.063 μM (0.050 μg mL-1). No increased toxicity toward mammalian cells was observed by the combination of COEs, as indicated by cytotoxicity measurements using the 3T3 cell line. Indeed, there is an extended ratio between the half maximal inhibitory concentration based on 3T3 cells to MIC against MRSA from 12 to greater than 256. Biophysical experiments using liposome models suggest that COE-S6 promotes the interactions between COE-D8 and lipid bilayers, which is in agreement with damages of cellular permeability and morphology, as observed by confocal microscopy and scanning electron microscopy. The application of a combined mixture of COEs further demonstrates their promising potential as a new class of antimicrobial agents with high efficacy and selectivity.

Antibiofilm Platform based on the Combination of Antimicrobial Polymers and Essential Oils

The development of potent strategies to counter microbial biofilm is an urgent priority in healthcare. The majority of bacterial infections in humans are biofilm related, however, effective treatments are still lacking especially for combating multidrug-resistant (MDR) strains. Herein, we report an effective antibiofilm platform based on the use of synthetic antimicrobial polymers in combination with essential oils, where the antimicrobial polymers play a secondary role as delivery vehicle for essential oils. Two ternary antimicrobial polymers consisting of cationic primary amines, low-fouling oligo(ethylene glycol) and hydrophobic ethylhexyl groups were synthesized in the form of random and block copolymers, and mixed with either carvacrol or eugenol. Coadministration of these compounds improved the efficacy against Pseudomonas aeruginosa biofilms compared to the individual compounds. We observed about a 60-75% and 70-85% biofilm inhibition effect for all tested combinations against wild-type P. aeruginosa PAO1 and MDR strain PA37, respectively, upon 6.5 h of incubation time. While both random and block copolymers demonstrated similar biofilm inhibition potencies in combination with essential oils, only the block copolymer acted synergistically with essential oils in killing biofilm. Treatment of PAO1 biofilm for 20 min with the block copolymer-oil combinations resulted in the killing of >99.99% of biofilm bacteria. This synergistic bactericidal activity is attributed to the targeted delivery of essential oils to the biofilm, driven by the electrostatic interaction between positively charged delivery vehicles, in the form of polymeric micelles, and negatively charged bacteria. This study thus highlights the advantage of combining essential oils and antimicrobial polymers as an effective avenue for antibacterial applications.

Synergy between Synthetic Antimicrobial Polymer and Antibiotics: A Promising Platform To Combat Multidrug-Resistant Bacteria

The failure of many antibiotics in the treatment of chronic infections caused by multidrug-resistant (MDR) bacteria necessitates the development of effective strategies to combat this global healthcare issue. Here, we report an antimicrobial platform based on the synergistic action between commercially available antibiotics and a potent synthetic antimicrobial polymer that consists of three key functionalities: low-fouling oligoethylene glycol, hydrophobic ethylhexyl, and cationic primary amine groups. Checkerboard assays with Pseudomonas aeruginosa (P. aeruginosa) and Escherichia coli demonstrated synergy between our synthetic antimicrobial polymer and two antibiotics, doxycycline and colistin. Coadministration of these compounds significantly improved the bacteriostatic efficacy especially against MDR P. aeruginosa strains PA32 and PA37, where the minimal inhibitory concentrations (MICs) of polymer and antibiotics were reduced by at least 4-fold. A synergistic killing activity was observed when the antimicrobial polymer was used in combination with doxycycline, killing >99.999% of planktonic and biofilm P. aeruginosa PAO1 upon a 20 min treatment at a polymer concentration of 128 μg mL^-1 (4.6 μM) and doxycycline concentration of 64 μg mL^-1 (133.1 μM). In addition, this synergistic combination reduced the rate of resistance development in P. aeruginosa compared to individual compounds and was also capable of reviving susceptibility to treatment in the resistant strains.

High Throughput Screening of Glycopolymers: Balance between Cytotoxicity and Antibacterial Property

To search for synthetic agents with low cytotoxicity and good antibacterial activity is essential for antimicrobial applications. Here we report a high throughput technique that carried out in multiwell plates via recyclable-catalyst-aided, opened-to-air, and sunlight-photolyzed RAFT (ROS-RAFT) polymerization. By using this method, three key monomers (MAG the sugar unit, DMAPMA the positively charged monomer, and DEMAA the hydrophobic monomer) can be polymerized in a controlled manner to afford glycopolymers. This simple high throughput technology is used to synthesize glycopolymers with variable compositions. The bacterial adhesion/killing ability and cytotoxicity of synthesized polymers have been evaluated, and glycopolymers with certain composition can achieve a balance of low cytotoxic and good antibacterial activity.

Poly(silsesquioxanes) and poly(siloxanes) grafted with N-acetylcysteine for eradicating mature bacterial biofilms in water environment

Bacteria adapt to their living environment forming organised biofilms. The survival strategy makes them more resistant to disinfectants, which results in acute biofilm-caused infections, secondary water pollution by biofilm metabolites and bio-corrosion. New, efficient and environmentally friendly strategies must be developed to solve this problem. Water soluble N-acetyl derivative of L-cysteine (NAC) is a non-toxic compound of mucolytic and bacteriostatic properties that can interfere with the formation of biofilms. However, it can also be a source of C and N for undesired microorganisms, as well as a reason for some adverse human health effects. Consequently, novel procedures are required, that would decrease the take-up of NAC but not reduce its antibacterial properties. We have grafted N-acetyl-l-cysteine onto linear poly(vinylsilsesquioxanes) and poly(methylvinylsiloxanes) via thiol-ene addition. Antibacterial activity of the obtained hybrid materials (respectively, NAC-Si-1 and NAC-Si-2) was determined against Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus strains. Native NAC inhibited growth of planktonic cells for the tested bacteria at concentration 0.25% w/v. Inhibition with equivalent solutions of the polymer derivatives was less effective due to the lack of SH groups. However, the tested polymers proved to be quite effective in eradication of mature biofilms. Treatment with 1% w/v emulsions of the hybrid polymers resulted in a significant reduction of viable cells in biofilm matrix despite the absence of thiol moieties. The effect was most pronounced for mature biofilms of S. aureus eradicated with NAC-Si-2.