Anti-biofilm studies of synthetic imidazolium salts on dental biofilm in vitro

Role of small molecules and nanoparticles in effective inhibition of microbial biofilms: A ray of hope in combating microbial resistance

Microbial biofilms pose a severe threat to global health, as they are associated with deadly chronic infections and antibiotic resistance. To date, very few drugs are in clinical practice that specifically target microbial biofilms. Therefore, there is an urgent need for the development of novel therapeutic options targeting biofilm-related infections. In this review, we discuss nearly seventy-five different molecular scaffolds published over the last decade (2010-2023) which have exhibited their biofilm inhibition potential. For convenience, we have classified these into five different sub-groups based on their origin and design (excluding peptides as they are placed in between small molecules and biologics), namely, heterocycles; inorganic small molecules & metal complexes; small molecules decorated nanoparticles; small molecules derived from natural products (both plant and marine sources); and small molecules designed by in-silico approach. These antibiofilm agents are capable of disrupting microbial biofilms and can offer a promising avenue for future developments in human medicine. A hitherto review of this kind will lay a platform for the researchers to find new molecular entities to curb the serious menace of antimicrobial resistance especially caused by biofilms.

Effects of caffeic acid phenethyl ester against multi-species cariogenic biofilms

Dental caries is a biofilm-related disease, widely perceived to be caused by oral ecological imbalance when cariogenic/aciduric bacteria obtain an ecological advantage. Compared with planktonic bacteria, dental plaques are difficult to remove under extracellular polymeric substance protection. In this study, the effect of caffeic acid phenethyl ester (CAPE) on a preformed cariogenic multi-species biofilm was evaluated, which was comprised of cariogenic bacteria (Streptococcus mutans), commensal bacteria (Streptococcus gordonii), and a pioneer colonizer (Actinomyces naeslundii). Our result revealed that treatment with 0.08 mg/mL CAPE reduced live S. mutans in the preformed multi-species biofilm while not significantly changing the quantification of live S. gordonii. CAPE significantly reduced the production of lactic acid, extracellular polysaccharide, and extracellular DNA and made the biofilm looser. Moreover, CAPE could promote the H2O2 production of S. gordonii and inhibit the expression of SMU.150 encoding mutacin to modulate the interaction among species in biofilms. Overall, our results suggested that CAPE could inhibit the cariogenic properties and change the microbial composition of the multi-species biofilms, indicating its application potential in dental caries prevention and management.

Theranostic gold-in-gold cage nanoparticles enable photothermal ablation and photoacoustic imaging in biofilm-associated infection models

Biofilms are structured communities of microbial cells embedded in a self-produced matrix of extracellular polymeric substances. Biofilms are associated with many health issues in humans, including chronic wound infections and tooth decay. Current antimicrobials are often incapable of disrupting the polymeric biofilm matrix and reaching the bacteria within. Alternative approaches are needed. Here, we described a complex structure of a dextran-coated gold-in-gold cage nanoparticle that enabled photoacoustic and photothermal properties for biofilm detection and treatment. Activation of these nanoparticles with a near infrared laser could selectively detect and kill biofilm bacteria with precise spatial control and in a short timeframe. We observed a strong biocidal effect against both Streptococcus mutans and Staphylococcus aureus biofilms in mouse models of oral plaque and wound infections, respectively. These effects were over 100 times greater than those seen with chlorhexidine, a conventional antimicrobial agent. Moreover, this approach did not adversely affect surrounding tissues. We concluded that photothermal ablation using theranostic nanoparticles is a rapid, precise, and nontoxic method to detect and treat biofilm-associated infections.

Theranostic gold in a gold cage nanoparticle for photothermal ablation and photoacoustic imaging of skin and oral infections

Biofilms are structured communities of microbial cells embedded in a self-produced matrix of extracellular polymeric substances. Biofilms are associated with many health issues in humans, including chronic wound infections and tooth decay. Current antimicrobials are often incapable of disrupting the polymeric biofilm matrix and reaching the bacteria within. Alternative approaches are needed. Here, we describe a unique structure of dextran coated gold in a gold cage nanoparticle that enables photoacoustic and photothermal properties for biofilm detection and treatment. Activation of these nanoparticles with a near infrared laser can selectively detect and kill biofilm bacteria with precise spatial control and in a short timeframe. We observe a strong biocidal effect against both Streptococcus mutans and Staphylococcus aureus biofilms in mouse models of oral plaque and wound infections respectively. These effects were over 100 times greater than that seen with chlorhexidine, a conventional antimicrobial agent. Moreover, this approach did not adversely affect surrounding tissues. We conclude that photothermal ablation using theranostic nanoparticles is a rapid, precise, and non-toxic method to detect and treat biofilm-associated infections.

Significantly improved antifouling capability of silicone rubber surfaces by covalently bonded acrylated agarose towards biomedical applications

Bacteria have the extraordinary ability to adhere to biomaterial surfaces and form multicellular structures known as biofilms, which have a detrimental impact on the performance of medical devices. Herein, an investigation highlighted the effective inhibition of bacteria adhesion and overgrowth on silicone rubber surface by grafting polysaccharide, agarose (AG), to construct hydrophilic and negatively charged surfaces. Because of the strong hydration capacity of agarose, the water contact angle of the modified silicone rubber surfaces was significantly reduced from 107.6 ± 2.7° to 19.3 ± 2.6°, which successfully limited bacterial adherence. Most importantly, the durability and stability of coating were observed after 10 days of simulated dynamic microenvironment in vivo, exhibiting a long service life. This modification method did not compromise biocompatibility of silicone rubber, opening a door to new applications for silicone rubber in the field of biomedical materials.