Preliminary In Vitro Cytotoxicity, Mutagenicity and Antitumoral Activity Evaluation of Graphene Flake and Aqueous Graphene Paste

Cytotoxicity and antibacterial susceptibility assessment of a newly developed pectin-chitosan polyelectrolyte composite for dental implants

Biopolymers such as chitosan and pectin are currently attracting significant attention because of their unique properties, which are valuable in the food industry and pharmaceutical applications. These properties include non-toxicity, compatibility with biological systems, natural decomposition ability, and structural adaptability. The objective of this study was to assess the performance of two different ratios of pectin-chitosan polyelectrolyte composite (PCPC) after applying them as a coating to commercially pure titanium (CpTi) substrates using electrospraying. The PCPC was studied in ratios of 1:2 and 1:3, while the control group consisted of CpTi substrates without any coating. The pull-off adhesion strength, cytotoxicity, and antibacterial susceptibility tests were utilized to evaluate the PCPC coatings. In order to determine whether the composite coating was the result of physical blending or chemical bonding, the topographic surface parameters were studied using Fourier transform infrared spectroscopy (FTIR) and atomic force microscopy (AFM). PCPC (1:3) had the highest average cell viability of 93.42, 89.88, and 86.85% after 24, 48, and 72 h, respectively, as determined by the cytotoxicity assay, when compared to the other groups. According to the Kirby-Bauer disk diffusion method for testing antibacterial susceptibility, PCPC (1:3) showed the highest average diameter of the zone of inhibition, measuring 14.88, 14.43, and 11.03 mm after 24, 48, and 72 h of incubation, respectively. This difference was highly significant compared to Group 3 at all three time periods. PCPC (1:3) exhibited a significantly higher mean pull-off adhesion strength (521.6 psi) compared to PCPC (1:2), which revealed 419.5 psi. PCPC (1:3) coated substrates exhibited better surface roughness parameters compared to other groups based on the findings of the AFM. The FTIR measurement indicated that both PCPC groups exhibited a purely physical blending in the composite coating. Based on the extent of these successful in vitro experiments, PCPC (1:3) demonstrates its potential as an effective coating layer. Therefore, the findings of this study pave the way for using newly developed PCPC after electrospraying coating on CpTi for dental implants.

Repurposing Castanea sativa Spiny Burr By-Products Extract as a Potentially Effective Anti-Inflammatory Agent for Novel Future Biotechnological Applications

The concept of a "circular bioeconomy" holds great promise for the health, cosmetic, and nutrition sectors by re-using Castanea sativa (Mill.) by-products. This sustainable resource is rich in bioactive secondary metabolites with antioxidant and anti-inflammatory properties. By transforming these by-products into high-value products for human health, we can promote sustainable economic growth and reduce the environmental impact of traditional waste disposal, adding value to previously underutilized resources. In the present study, we investigated the antioxidant capacity, phytochemical composition, and in vitro antioxidant and anti-inflammatory activity of C. sativa burr (CSB) aqueous extract. The spectrophotometric study revealed high total phenolic content (TPC) values with significant antioxidant and anti-radical properties. Using UPLC-MS/MS techniques, the phytochemical investigation identified 56 metabolites, confirming the presence of phenolic compounds in CSBs. In addition, CSBs significantly downregulated pro-inflammatory mediators in LPS-stimulated RAW 264.7 macrophage cells without significant cell toxicity. Lastly, in silico studies pinpointed three kinases from RAW 264.7 cells as binding partners with ellagic acid, the predominant compound found in our extract. These findings strongly advocate for the recycling and valorization of C. sativa by-products, challenging their conventional classification as mere "waste".

Biomacromolecular and Toxicity Responses of Bacteria upon the Nano-Bio Interfacial Interactions with Ti3C2Tx Nanosheets

The biomolecular responses of bacteria to 2D nanosheets that result from nano-bio interfacial interactions remain to be thoroughly examined. Herein, Fourier transform infrared (FTIR) multivariate and 2D correlation analyses were performed to assess the composition and conformational changes in bacterial biomacromolecules (lipids, polysaccharides, and carbohydrates) upon exposure to Ti3C2Tx nanosheets. General toxicity assays, 3D excitation-emission matrix fluorescence analyses, extended Derjaguin-Landau-Verwey-Overbeek theory interaction calculations, and isothermal titration calorimetry were also performed. Our results demonstrate that Ti3C2Tx nanosheets considerably impact Gram-positive bacteria (Bacillus subtilis), causing oxidative damage and inactivation by preferentially interacting with and disrupting the cell walls. The bilayer membrane structure of Gram-negative bacteria (Escherichia coli) endows them with increased resistance to Ti3C2Tx nanosheets. The unmodified nanosheets had a higher affinity to bacterial protein components with lower toxicity due to their susceptibility to oxidation. Surface modification with KOH or hydrazine (HMH), particularly HMH, induced stronger dispersion, antioxidation, and affinity to bacterial phospholipids, which resulted in severe cell membrane lipid peroxidation and bacterial inactivation. These findings provide valuable insight into nano-bio interfacial interactions, which can facilitate the development of antimicrobial and antifouling surfaces and contribute to the evaluation of the environmental risks of nanomaterials.

Structuring and De-Structuring of Nanovectors from Algal Lipids: Simulated Digestion, Preliminary Antioxidant Capacity and In Vitro Tests

Biocompatible nanocarriers can be obtained by lipid extraction from natural sources such as algal biomasses, which accumulate different lipid classes depending on the employed culture media. Lipid aggregates can be distinguished according to supramolecular architecture into lamellar and nonlamellar structures. This distinction is mainly influenced by the lipid class and molecular packing parameter, which determine the possible values of interfacial curvature and thus the supramolecular symmetries that can be obtained. The nanosystems prepared from bio-sources are able to self-assemble into different compartmentalized structures due to their complex composition. They also present the advantage of increased carrier-target biocompatibility and are suitable to encapsulate and vehiculate poorly water-soluble compounds, e.g., natural antioxidants. Their functional properties stem from the interplay of several parameters. Following previous work, here the functionality of two series of structurally distinct lipid nanocarriers, namely liposomes and cubosomes deriving from algal biomasses with different lipid composition, is characterized. In the view of their possible use as pharmaceutical or nutraceutical formulations, both types of nanovectors were loaded with three well-known antioxidants, i.e., curcumin, α-tocopherol and piperine, and their carrier efficacy was compared considering their different structures. Firstly, carrier stability in biorelevant conditions was assessed by simulating a gastrointestinal tract model. Then, by using an integrated chemical and pharmacological approach, the functionality in terms of encapsulation efficiency, cargo bioaccessibility and kinetics of antioxidant capacity by UV-Visible spectroscopy was evaluated. Subsequently, in vitro cytotoxicity and viability tests after administration to model cell lines were performed. As a consequence of this investigation, it is possible to conclude that nanovectors from algal lipids, i.e., cubosomes and liposomes, can be efficient delivery agents for lipophilic antioxidants, being able to preserve and enhance their activity toward different targets while promoting sustained release.