Exploring the Effects of Lignin Nanoparticles in Different Zebrafish Inflammatory Models.

Purpose: Lignin is the most abundant source of aromatic biopolymers and has gained interest in industrial and biomedical applications due to the reported biocompatibility and defense provided against bacterial and fungal pathogens, besides antioxidant and UV-blocking properties. Especially in the form of nanoparticles (NPs), lignin may display also antioxidant and anti-inflammatory activities. Methods: To evaluate these characteristics, sonochemically nano-formulated pristine lignin (LigNPs) and enzymatically-phenolated one (PheLigNPs) were used to expose zebrafish embryos, without chorion, at different concentrations. Furthermore, two different zebrafish inflammation models were generated, by injecting Pseudomonas aeruginosa lipopolysaccharide (LPS) and by provoking a wound injury in the embryo caudal fin. The inflammatory process was investigated in both models by qPCR, analyzing the level of genes as il8, il6, il1ß, tnfα, nfkbiaa, nfk2, and ccl34a.4, and by the evaluation of neutrophils recruitment, taking advantage of the Sudan Black staining, in the presence or not of LigNPs and PheLigNPs. Finally, the Wnt/ß-catenin pathway, related to tissue regeneration, was investigated at the molecular level in embryos wounded and exposed to NPs. Results: The data obtained demonstrated that the lignin-based NPs showed the capacity to induce a positive response during an inflammatory event, increasing the recruitment of cytokines to accelerate their chemotactic function. Moreover, the LigNPs and PheLigNPs have a role in the resolution of wounds, favoring the regeneration process. Conclusion: In this paper, we used zebrafish embryos within 5 days post fertilization (hpf). Despite being an early-stage exemplary, the zebrafish embryos have proven their potential as predicting models. Further long-term experiments in adults will be needed to explore completely the biomedical capabilities of lignin NPs. The results underlined the safety of both NPs tested paved the way for further evaluations to exploit the anti-inflammatory and pro-healing properties of the lignin nanoparticles examined.

Enzymatically Built Nanoenabled Antimicrobial Coating on Urinary Catheters.

Catheter-associated urinary tract infections represent a major share of nosocomial infections, and are associated with longer periods of hospitalization and a huge financial burden. Currently, there are only a handful of commercial materials that reduce biofilm formation on urinary catheters, mostly relying on silver alloys. Therefore, we combined silver-phenolated lignin nanoparticles with poly(carboxybetaine) zwitterions to build a composite antibiotic-free coating with bactericidal and antifouling properties. Importantly, the versatile lignin chemistry enabled the formation of the coating in situ, enabling both the nanoparticle grafting and the radical polymerization by using only the oxidative activity of laccase. The resulting surface efficiently prevented nonspecific protein adsorption and reduced the bacterial viability on the catheter surface by more than 2 logs under hydrodynamic flow, without exhibiting any apparent signs of cytotoxicity. Moreover, the said functionality was maintained over a week both in vitro and in vivo, whereby the animal models showed excellent biocompatibility.

Dual electro-/pH-responsive nanoparticle/hydrogel system for controlled delivery of anticancer peptide.

An electro-chemo-responsive carrier has been engineered for the controlled release of a highly hydrophilic anticancer peptide, CR(NMe)EKA (Cys-Arg- N-methyl-Glu-Lys-Ala). Remotely controlled on demand release of CR(NMe)EKA, loaded in electro-responsive poly(3,4-ethylenedioxythiophene) (PEDOT) nanoparticles, has been achieved by applying electrical stimuli consisting of constant positive (+0.50 V) or negative voltages (-0.50 V) at pre-defined time intervals. In addition, after loading CR(NMe)EKA/PEDOT nanoparticles into an injectable pH responsive hydrogel formed by phenylboronic acid grafted to chitosan (PBA-CS), the efficiency of the controlled peptide release has increased approximately by a factor of 2.6. The hydration ratio of such hydrogel is significantly lower in acidic environments than in neutral and basic media, which has been attributed to the dissociation of the boronate bonds between polymer chains. Hence, the electro-controlled peptide release from PBA-CS/CR(NMe)EKA/PEDOT hydrogels, in the acidic environment of tumors, combines the effects of the oxidation and reduction of PEDOT chains on the interactions with the peptide and the carrier, with the peptide concentration gradient at the interface between the collapsed hydrogel and the release medium. Furthermore, the peptide released by electro-stimulation preserved its bioactivity assessed by promoting human prostate cancer cells death. Overall, this work is a promising attempt to develop a carrier platform for small hydrophilic anticancer peptides, which delivery rationale is synergistically regulated by the electrical and pH responsiveness of the carrier.

Mussel-Inspired Sonochemical Nanocomposite Coating on Catheters for Prevention of Urinary Infections.

Catheter-associated urinary tract infections are the most common hospital-acquired infections and cause patient discomfort, increased morbidity, and prolonged stays, altogether posing a huge burden on healthcare services. Colonization occurs upon insertion, or later by ascending microbes from the rich periurethral flora, and is therefore virtually unavoidable by medical procedures. Importantly, the dwell time is a significant risk factor for bacteriuria because it gives biofilms time to develop and mature. This is why we engineer antibacterial and antibiofilm coating through ultrasound- and nanoparticle-assisted self-assembly on silicone surfaces and validate it thoroughly in vitro and in vivo. To this end, we combine bimetallic silver/gold nanoparticles, which exercise both biocidal and structural roles, with dopamine-modified gelatin in a facile and substrate-independent sonochemical coating process. The latter mussel-inspired bioadhesive potentiates the activity and durability of the coating while attenuating the intrinsic toxicity of silver. As a result, our approach effectively reduces biofilm formation in a hydrodynamic model of the human bladder and prevents bacteriuria in catheterized rabbits during a week of placement, outperforming conventional silicone catheters. These results substantiate the practical use of nanoparticle-biopolymer composites in combination with ultrasound for the antimicrobial functionalization of indwelling medical devices.

Protecting the Antibacterial Coating of Urinal Catheters for Improving Safety.

Catheter-associated urinary tract infections (CAUTI) are among the most common bacterial infections associated with prolonged hospitalization and increased healthcare expenditures. Despite recent advances in the prevention and treatment of these infections, there are still many challenges remaining, among them the creation of a durable catheter coating, which prevents bacterial biofilm formation. The current work reports on a method of protecting medical tubing endowed with antibiofilm properties. Silicone catheters coated sonochemically with ZnO nanoparticles (NPs) demonstrated excellent antibiofilm effects. Toward approval by the European Medicines Agency, it was realized that the ZnO coating would not withstand the regulatory requirements of avoiding dissolution for 14 days in artificial urine examination. Namely, after exposure to urine for 14 days, the coating amount was reduced by 90%. Additional coatings with either carbon or silica maintained antibiofilm activity against Staphylococcus aureus while resisting dissolution in artificial urine for 14 days (C- or SiO2-protected catheters exhibited only 29% reduction). HR-SEM images of the protected catheters indicate the presence of the ZnO coating as well as the protective layer. Antibiofilm activity of all catheters was evaluated both before and after exposure to artificial urine. It was shown that before artificial urine exposure, all coated catheters showed high antibiofilm properties compared to the uncoated control. Exposure of ZnO-coated catheters, without the protective layer, to artificial urine had a significant effect exhibited by the decrease in antibiofilm activity by almost 2 orders of magnitude, compared to unexposed catheters. Toxicity studies performed using a reconstructed human epidermis demonstrated the safety of the improved coating. Exposure of the epidermis to ZnO catheter extracts in artificial urine affects tissue viability compared with control samples, which was not observed in the case of ZnO NPs coating with SiO2 or C. We suggest that silica and carbon coatings confer some protection against zinc ions release, improving ZnO coating safety.