Antibacterial and Biofilm-Disrupting Coatings from Resin Acid-Derived Materials

Monomer design strategies to create natural product-based polymer materials

In an effort towards enhancing function and sustainability, natural products have become of interest in the field of polymer chemistry.

A Biodegradable Polycationic Paint that Kills Bacteria in Vitro and in Vivo

Bacterial colonization and subsequent formation of biofilms onto surfaces of medical devices and implants is a major source of nosocomial infections. Most antibacterial coatings to combat infections are either metal-based or nondegradable-polymer-based and hence limited by their nondegradability and unpredictable toxicity. Moreover, to combat infections effectively, the coatings are required to display simultaneous antibacterial and antibiofilm activity. Herein we report biocompatible and biodegradable coatings based on organo-soluble quaternary chitin polymers which were immobilized noncovalently onto surfaces as bactericidal paint. The polycationic paint was found to be active against both drug-sensitive and -resistant bacteria such as methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus faecium (VRE), and β-lactam-resistant Klebsiella pneumoniae. The cationic polymers were shown to interact with the negatively charged bacterial cell membrane and disrupt the membrane integrity, thereby causing leakage of intracellular constituents and cell death upon contact. Importantly, surfaces coated with the polymers inhibited formation of biofilms against both Gram-positive S. aureus and Gram-negative E. coli, two of the most clinically important bacteria that form biofilms. Surfaces coated with the polymers displayed negligible toxicity against human erythrocytes and embryo kidney cells. Notably, the polymers were shown to be susceptible toward lysozyme. Furthermore, subcutaneous implantation of polymer discs in rats led to 15-20% degradation in 4 weeks thereby displaying their biodegradability. In a murine model of subcutaneous infection, polymer-coated medical-grade catheter reduced MRSA burden by 3.7 log compared to that of noncoated catheter. Furthermore, no biofilm development was observed on the coated catheters under in vivo conditions. The polycationic materials thus developed herein represent a novel class of safe and effective coating agents for the prevention of device-associated infections.

Antibacterial profiling of abietane-type diterpenoids

Abietic and dehydroabietic acid are interesting diterpenes with a highly diverse repertoire of associated bioactivities. They have, among others, shown antibacterial and antifungal activity, potentially valuable in the struggle against the increasing antimicrobial resistance and imminent antibiotic shortage. In this paper, we describe the synthesis of a set of 9 abietic and dehydroabietic acid derivatives containing amino acid side chains and their in vitro antimicrobial profiling against a panel of human pathogenic microbial strains. Furthermore, their in vitro cytotoxicity against mammalian cells was evaluated. The experimental results showed that the most promising compound was 10 [methyl N-(abiet-8,11,13-trien-18-yl)-d-serinate], with an MIC₉₀ of 60μg/mL against Staphylococcus aureus ATCC 25923, and 8μg/mL against methicillin-resistant S. aureus, Staphylococcus epidermidis and Streptococcus mitis. The IC₅₀ value for compound 10 against Balb/c 3T3 cells was 45μg/mL.

Programmable biomaterials for dynamic and responsive drug delivery

Biomaterials are continually being designed that enable new methods for interacting dynamically with cell and tissues, in turn unlocking new capabilities in areas ranging from drug delivery to regenerative medicine. In this review, we explore some of the recent advances being made in regards to programming biomaterials for improved drug delivery, with a focus on cancer and infection. We begin by explaining several of the underlying concepts that are being used to design this new wave of drug delivery vehicles, followed by examining recent materials systems that are able to coordinate the temporal delivery of multiple therapeutics, dynamically respond to changing tissue environments, and reprogram their bioactivity over time.

Simple and cost-effective polycondensation routes to antimicrobial consumer products

Cost-effective macromolecular antimicrobials were synthesized to explore a variety of chemical functional groups that target antimicrobial performance and reduce cytotoxicity.