Functional insights to the development of bioactive material for combating bacterial infections

Synthesis of silver nanoparticles embedded into melamine polyaminal networks as antibacterial and anticancer active agents

Silver nanoparticles were successfully incorporated into a melamine-based polymer, resulting in the synthesis of (Ag NPs@Bipy-PAN) through a reverse double solvent approach. The synthesised Ag NPs@Bipy-PAN polymer underwent extensive characterisation through Powder X-ray Diffraction (PXRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy and Energy Dispersive X-ray (EDX) and Thermal Gravimetric Analysis. PXRD analysis confirmed the successful encapsulation of Ag nanoparticles and provided insights into the amorphous nature of the polymer following encapsulation. SEM and EDX analyses further corroborated the presence and distribution of Ag nanoparticles on the polymer surface. The biological efficacy of the Ag NPs@Bipy-PAN polymer was evaluated through antibacterial, anti-breast cancer, and biocompatibility assays. The results demonstrated notable antibacterial and anticancer activities, with significant efficacy against bacterial strains and breast cancer cells. Biocompatibility assessments indicated acceptable compatibility, particularly at a concentration of 2.5 mg/mL, compared to untreated control cells. These findings suggest that Ag NPs@Bipy-PAN has considerable potential as a candidate for cancer-targeted and antimicrobial drug delivery systems. The incorporation of silver nanoparticles into the melamine-based polymer enhances the safety profile of these systems in in vivo conditions, making them a viable option for advanced therapeutic applications.

Antimicrobial Photodynamic Therapy: Self-Disinfecting Surfaces for Controlling Microbial Infections

Microbial infections caused by bacteria, viruses, and fungi pose significant global health threats in diverse environments. While conventional disinfection methods are effective, their reliance on frequent chemical applications raises concerns about resistance and environmental impact. Photodynamic self-disinfecting surfaces have emerged as a promising alternative. These surfaces incorporate photosensitizers that, when exposed to light, produce reactive oxygen species to target and eliminate microbial pathogens. This review explores the concept and mechanism of photodynamic self-disinfecting surfaces, highlighting the variety and characteristics of photosensitizers integrated into surfaces and the range of light sources used across different applications. It also highlights the effectiveness of these surfaces against a broad spectrum of pathogens, including bacteria, viruses, and fungi, while also discussing their potential for providing continuous antimicrobial protection without frequent reapplication. Additionally, the review addresses both the advantages and limitations associated with photodynamic self-disinfecting surfaces and concludes with future perspectives on advancing this technology to meet ongoing challenges in infection control.

Harnessing antimicrobial peptide-coupled photosensitizer to combat drug-resistant biofilm infections through enhanced photodynamic therapy

Bacterial biofilm-associated infection was one of the most serious threats to human health. However, effective drugs for drug-resistance bacteria or biofilms remain rarely reported. Here, we propose an innovative strategy to develop a multifunctional antimicrobial agent with broad-spectrum antibacterial activity by coupling photosensitizers (PSs) with antimicrobial peptides (AMPs). This strategy capitalizes on the ability of PSs to generate reactive oxygen species (ROS) and the membrane-targeting property of AMPs (KRWWKWIRW, a peptide screened by an artificial neural network), synergistically enhancing the antimicrobial activity. In addition, unlike conventional aggregation-caused quenching (ACQ) photosensitizers, aggregation-induced emission (AIE) PSs show stronger fluorescence emission in the aggregated state to help visualize the antibacterial mechanism. In vitro antibacterial experiments demonstrated the excellent killing effects of the developed agent against both Gram-positive (G+) and Gram-negative (G-) bacteria. The bacterial-aggregations induced ability enhanced the photoactivatable antibacterial activity against G- bacteria. Notably, it exhibited a significant effect on destroying MRSA biofilms. Moreover, it also showed remarkable efficacy in treating wound infections in mice in vivo. This multifunctional antimicrobial agent holds significant potential in addressing the challenges posed by bacterial biofilm-associated infections and drug-resistant bacteria.

Nanozyme-Engineered Hydrogels for Anti-Inflammation and Skin Regeneration

Inflammatory skin disorders can cause chronic scarring and functional impairments, posing a significant burden on patients and the healthcare system. Conventional therapies, such as corticosteroids and nonsteroidal anti-inflammatory drugs, are limited in efficacy and associated with adverse effects. Recently, nanozyme (NZ)-based hydrogels have shown great promise in addressing these challenges. NZ-based hydrogels possess unique therapeutic abilities by combining the therapeutic benefits of redox nanomaterials with enzymatic activity and the water-retaining capacity of hydrogels. The multifaceted therapeutic effects of these hydrogels include scavenging reactive oxygen species and other inflammatory mediators modulating immune responses toward a pro-regenerative environment and enhancing regenerative potential by triggering cell migration and differentiation. This review highlights the current state of the art in NZ-engineered hydrogels (NZ@hydrogels) for anti-inflammatory and skin regeneration applications. It also discusses the underlying chemo-mechano-biological mechanisms behind their effectiveness. Additionally, the challenges and future directions in this ground, particularly their clinical translation, are addressed. The insights provided in this review can aid in the design and engineering of novel NZ-based hydrogels, offering new possibilities for targeted and personalized skin-care therapies.

Nanomedicine against biofilm infections: A roadmap of challenges and limitations

Microbial biofilms are complex three-dimensional structures where sessile microbes are embedded in a polymeric extracellular matrix. Their resistance toward the host immune system as well as to a diverse range of antimicrobial treatments poses a serious health and development threat, being in the top 10 global public health threats declared by the World Health Organization. In an effort to combat biofilm-related microbial infections, several strategies have been developed to independently eliminate biofilms or to complement conventional antibiotic therapies. However, their limitations leave room for other treatment alternatives, where the application of nanotechnology to biofilm eradication has gained significant relevance in recent years. Their small size, penetration efficiency, and the design flexibility that they present makes them a promising alternative for biofilm infection treatment, although they also present set-backs. This review aims to describe the main possibilities and limitations of nanomedicine against biofilms, while covering the main aspects of biofilm formation and study, and the current therapies for biofilm treatment. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Infectious Disease Toxicology and Regulatory Issues in Nanomedicine > Toxicology of Nanomaterials Toxicology and Regulatory Issues in Nanomedicine > Regulatory and Policy Issues in Nanomedicine.

Eco-Friendly Cellulose-Based Nonionic Antimicrobial Polymers with Excellent Biocompatibility, Nonleachability, and Polymer Miscibility

This study aims to prepare natural biomass-based nonionic antimicrobial polymers with excellent biocompatibility, nonleachability, antimicrobial activity, and polymer miscibility. Two new cellulose-based nonionic antimicrobial polymers (MIPA and MICA) containing many terminal indole groups were synthesized using a sustainable one-pot method. The structures and properties of the nonionic antimicrobial polymers were characterized using nuclear magnetic resonance hydrogen spectroscopy (1H NMR), infrared spectroscopy (FTIR), wide-angle X-ray diffractometry (XRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), gel chromatography (GPC), and other analytical techniques. The results showed that microcrystalline cellulose (MCC) molecules combined with indole derivatives through an esterification reaction to produce MICA and MIPA. The crystallinity of the prepared MICA and MIPA molecules decreased after MCC modification; their morphological structure changed from short fibrous to granular and showed better thermal stability and solubility. The paper diffusion method showed that both nonionic polymers had good bactericidal effects against the two common pathogenic bacteria Escherichia coli (E. coli, inhibition zone diameters >22 mm) and Staphylococcus aureus (S. aureus, inhibition zone diameters >38 mm). Moreover, MICA and MIPA showed good miscibility with biodegradable poly(vinyl alcohol) (PVA), and the miscible cellulose-based composite films (PVA-MICA and PVA-MIPA) showed good phase compatibility, light transmission, thermal stability (maximum thermal decomposition temperature >300 °C), biocompatibility, biological cell activity (no cytotoxicity), nonleachability, antimicrobial activity, and mechanical properties (maximum fracture elongation at >390%).