Are antibiotic-functionalized nanoparticles a promising tool in antimicrobial therapies?

Ofloxacin@Doxorubicin-Epirubicin functionalized MCM-41 mesoporous silica-based nanocarriers as synergistic drug delivery tools for cancer related bacterial infections

Mesoporous silica nanoparticles (MNs) emerged as new promising drug-delivery platforms capable to overcome resistance in bacteria. Dual loading of drugs on these nanocarriers, exploiting synergistic interactions between the nanoparticles and the drugs, could be considered as a way to increase the efficacy against resistant bacteria with a positive effect even at very low concentrations. Considering that patients with cancer are highly susceptible to almost any type of bacterial infections, in this work, nanocarriers mesoporous silica-based, MNs and MNs@EPI were synthetized and submitted to single and/or dual loading of antibiotics (ofloxacin - OFLO) and anticancer drugs (Doxorubicin - DOX; Epirubicin - EPI), and investigated regarding their antibacterial activity against Escherichia coli, Staphylococcus aureus, methicillin-resistant S. aureus (MRSA), Enterococcus faecalis and Pseudomonas aeruginosa. Formulations containing ofloxacin such as MNs-OFLO, MNs-EPI + OFLO, MNs-DOX + OFLO and MNs@EPI + OFLO, present antibacterial activity in all bacterial strains tested. All these are more effective in E.coli with MIC and MBC values for MNs-OFLO, MNs-EPI + OFLO and MNs-DOX + OFLO of around 1 and 2 µg_nanomaterial/mL, corresponding to ofloxacin concentrations of 0.03, 0.02 and 0.04 µg/mL, respectively. In the cocktail formulations the conjugation of epirubicin with ofloxacin presents a more effective antibacterial activity with more than 3-fold reduction of ofloxacin concentration when comparing to the single ofloxacin system. By far, the most effective synergistic effect was obtained for the system where epirubicin was functionalized at nanoparticles surface (MNs@EPI), where a 40-fold and 33-fold reductions of ofloxacin concentration were obtained, in P. aeruginosa in comparison to the MNs-OFLO and MNs-EPI + OFLO systems, respectively. These effects are shown in all bacterial strains tested, even in strains that have acquired resistance mechanisms, such as MRSA.

Biofunctionalization of Natural Fiber-Reinforced Biocomposites for Biomedical Applications

In the last ten years, environmental consciousness has increased worldwide, leading to the development of eco-friendly materials to replace synthetic ones. Natural fibers are extracted from renewable resources at low cost. Their combination with synthetic polymers as reinforcement materials has been an important step forward in that direction. The sustainability and excellent physical and biological (e.g., biocompatibility, antimicrobial activity) properties of these biocomposites have extended their application to the biomedical field. This paper offers a detailed overview of the extraction and separation processes applied to natural fibers and their posterior chemical and physical modifications for biocomposite fabrication. Because of the requirements for biomedical device production, specialized biomolecules are currently being incorporated onto these biocomposites. From antibiotics to peptides and plant extracts, to name a few, this review explores their impact on the final biocomposite product, in light of their individual or combined effect, and analyzes the most recurrent strategies for biomolecule immobilization.

Shielding and stealth effects of zwitterion moieties in double-functionalized silica nanoparticles

Surface functionalization of silica nanoparticles (SiO₂NPs) has been considered as a promising strategy to develop target-specific nanostructures. However, finding a chemical functionalization that can be used as an active targeting moiety while preserving the nanoparticles colloidal stability in biological fluids is still challenging. We present here a dual surface modification strategy for SiO₂NPs where a zwitterion (ZW) and a biologically active group (BAG) (amino, mercapto or carboxylic functionalities) are simultaneously grafted on the nanoparticles' surface. The rationale behind this strategy is to generate colloidally stable nanoparticles and avoid the nonspecific protein adsorption due to ZW groups insertion, while the effective interaction with biosystems is guaranteed by the BAGs presence. The biological efficacy was tested against VERO cells, E. coli bacteria and Zika viruses and a similar trend was observed for all tested particles. The desirable "stealth property" to prevent nonspecific protein adhesion also generated a ZW shielding effect of the BAG functionality hindering their proper interaction and activity in cells, bacteria and viruses.