Polydopamine-functionalized selenium nanoparticles as an efficient photoresponsive antibacterial platform

The Use of Photoactive Polymeric Nanoparticles and Nanofibers to Generate a Photodynamic-Mediated Antimicrobial Effect, with a Special Emphasis on Chronic Wounds

This review is concerned with chronic wounds, with an emphasis on biofilm and its complicated management process. The basics of antimicrobial photodynamic therapy (PDT) and its underlying mechanisms for microbial eradication are presented. Intrinsically active nanocarriers (polydopamine NPs, chitosan NPs, and polymeric micelles) that can further potentiate the antimicrobial photodynamic effect are discussed. This review also delves into the role of photoactive electrospun nanofibers, either in their eluting or non-eluting mode of action, in microbial eradication and accelerating the healing of wounds. Synergic strategies to augment the PDT-mediated effect of photoactive nanofibers are reviewed.

Applications of peptide-functionalized or unfunctionalized selenium nanoparticles for the passivation of SARS-CoV-2 variants and the respiratory syncytial virus (RSV)

The SARS-CoV-2 Omicron subvariants BA.4, BA. 5 and XBB are currently causing a COVID resurgence due to their increased spreading and infectivity. These latest subvariants have been shown to be somewhat resistant to the most common vaccines even with the third dose. Moreover, it has been well documented that when patients stop taking some commercial therapies (such as Paxlovid), COVID from these variants may return and may even be more contagious. Herein, we tested unfunctionalized and functionalized selenium (Se) nanoparticles with three novel peptides (NapFFTLUFLTUTEKKKK, NapFFMLUFLMUMEKKKK, and NapFFSAVLQSGFKKKK) previously shown by themselves to passivate the Omicron SARS-CoV-2 BA.4, BA.5 and XBB variants. Se is a natural element in our diet and is well known to boost the immune system, thus, providing a complementary approach to viral infections. NapFFMLUFLMUMEKKKK showed a stronger inhibition ability at 98 % for Omicron BA.4 % and 96 % for Omicron BA.5 after just 15 min in vitro. Two types of Se nanoparticles (those made chemically or biogenically by cells) were tested to passivate the new SARS-CoV-2 XBB variant. Results showed that the combination of any peptide and using either type of Se NP, the Omicron subvariant XBB was inhibited by 100 % after just 15 min in vitro. Interestingly, the use of Se NPs alone outperformed the peptides in terms of XBB passivation. Also, in order to determine a mechanism of action, functionalizing Se nanoparticles with the NapFFSAVLQSGFKKKK peptide showed a high binding ability toward the chemotrypsin-like cysteine protease (SARS CoV-2 3CLpro). Further, as a demonstration of their versatility, these functionalized peptides also passivated the Respiratory Syncytial Virus (RSV). NapFFTLUFLTUTEKKKK and NapFFMLUFLMUMEKKKK showed in silico interactions with the fusion glycoprotein of RSV prompting in vitro RSV pseudo virus testing. Compared to the conventionally precipitated synthetic Se nanoparticles, in vitro results showed that biogenic Se functionalized with the peptides enhanced the inhibition RSV to 100 % after just 15 min of incubation. NapFFTLUFLTUTEKKKK and NapFFMLUFLMUMEKKKK also showed no potential genotoxicity or carcinogenic effects. The peptides showed good gastro-intestinal (GI) tract absorption and bioavailability as predicted using the partition coefficient (QP logPo/w), and high-water solubility as detected by QPlogS. According to these promising results, functionalizing biogenic Se nanoparticles with these novel peptides should be further studied in vivo for the improved diagnosis, prevention, and treatment of SARS-CoV-2, RSV, and other respiratory virus infections.

Different drug loading methods and antibiotic structure modulate the efficacy of polydopamine nanoparticles as drug nanocarriers

The inefficient delivery of antimicrobials to their target is a significant factor contributing to antibiotic resistance. As such, smart nanomaterials that respond to external stimuli are extensively explored for precise drug delivery. Here, we investigate how drug loading methods and the structure of antibiotics impact the effectiveness of photothermally active polydopamine nanoparticles (PDNPs) as a laser-responsive drug delivery system. We examine two loading methods: in-synthesis and post-synthesis, and evaluate how laser irradiation affects drug release. Density functional theory calculations are also performed to gain deeper insights into the drug-PDNP interactions. Our findings point to the critical role of antibiotic structure and drug loading method in the laser-responsive capabilities of PDNPs as drug nanocarriers. Our study offers valuable insights for optimizing the design and efficiency of PDNP-based drug delivery systems.

Biosynthesis of Quercetin-Loaded Melanin Nanoparticles for Improved Antioxidant Activity, Photothermal Antimicrobial, and NIR/pH Dual-Responsive Drug Release

Quercetin (QCT) is a promising dose-dependent nutraceutical that usually suffers from poor water solubility and low bioavailability issues. In this work, a novel QCT-loaded nanoscale delivery system was constructed based on the oxidative self-polymerization of melanin (Q@MNPs). The FT-IR, XRD, and Zeta potential analyses confirmed that QCT was successfully absorbed on the melanin nanoparticles (MNPs) via Π-Π and hydrogen bonding interactions. The encapsulation efficiency and particle size of Q@MNPs were 43.78% and 26.68 nm, respectively. Q@MNPs improved the thermal stability of QCT and the antioxidant properties in comparison to MNPs. Meanwhile, Q@MNPs presented fantastic photothermal conversion capacity and stability triggered by the NIR laser, which significantly enhanced the antibacterial capability with a sterilization rate of more than 98% against E. coli and S. aureus. More importantly, Q@MNPs exhibited NIR/pH dual-responsive drug release behavior and good biocompatibility (at concentrations of < 100 μg/mL). Thus, Q@MNPs show promising prospects for flavonoid delivery.

Synthesis and antibacterial activities of Ag-TiO2/ZIF-8

In recent years, massive bacterial infections have led to human illness and death, reminding us of the urgent need to develop effective and long-lasting antimicrobial materials. In this paper, Ag-TiO2/ZIF-8 with good environmental friendliness and biological antibacterial activity was prepared by solvothermal method. The structure and morphology of the synthesized materials were characterized by XRD, FT-IR, SEM-EDS, TEM, XPS, and BET. To investigate the antibacterial activity of the synthesized samples, Escherichia coli and Bacillus subtilis were used as target bacteria for experimental studies of zone of inhibition, bacterial growth curves, minimum bactericidal concentration and antibacterial durability. The results demonstrated that 20 wt.%Ag-TiO2/ZIF-8 had the best bacteriostatic effect on E. coli and B. subtilis under dark and UV conditions compared to TiO2 and ZIF-8. Under the same conditions, the diameter of the inhibition circle of 20 wt% Ag-TiO2/ZIF-8 is 8.5-11.5 mm larger than that of its constituent material 4 wt% Ag-TiO2, with more obvious antibacterial effect and better antibacterial performance. It is also proposed that the excellent antibacterial activity of Ag-TiO2/ZIF-8 is due to the synergistic effect of Ag-TiO2 and ZIF-8 under UV light. In addition, the prepared material has good stability and durability with effective antimicrobial activity for more than 5 months.