The uncontrolled spread of infectious diseases has driven the development of innovative materials designed to control microbial transmission and combat harmful pathogens. In this context, inorganic materials have emerged as promising candidates for bioactive coatings, offering intrinsic antimicrobial properties, biocompatibility, and potential eco-friendly applications. However, in accordance with the atom economy and safety criteria outlined by the Green Chemistry Principles, it is essential to ensure the use of the minimal effective dose of antimicrobial agents. This approach minimizes potential toxic effects while optimizing antimicrobial action. Chemometric tools have proven invaluable in designing and refining experimental protocols to achieve these objectives.

This communication proposes innovative strategies for synthesizing and characterizing bioactive coatings based on nanostructured and hybrid inorganic materials. Specifically, two cases of study are presented, focusing on zinc oxide and silver phosphate nanostructures. These materials were synthesized using green electrochemical and precipitation methods and subsequently embedded in polymeric matrices, such as polyvinyl alcohol (PVA), to develop bioactive films via self-standing procedures. Special emphasis was placed on optimizing experimental parameters through chemometric tools.

The chemometric approach enabled the development of materials with reproducible and tuneable properties, ensuring a synthetic yield exceeding 85%. Comprehensive analytical characterization—including electron microscopy, spectroscopy techniques, and solubility studies—was performed to establish correlations between synthesis conditions, material properties, and their potential applications. The antimicrobial structures have nano- and microscale dimensions, and the composite films ensure a controlled release of the metal ions over time.

The findings highlight the potential of these bioactive coatings for industrial-scale production, addressing critical challenges in antimicrobial resistance and promoting sustainable material development.

M.I. acknowledges the financial support from the ERC SEEDS UNIBA programme, project H93C23000660001, “REAL - More for less: REthinking AntimicrobiaL materials”. A.V.M. acknowledges funding by the European Union –NEXTGENERATIONEU – NRRP MISSION 4, COMPONENT 1.

An orthopedic implant is a medical device designed to replace a bone, joint, or cartilage due to damage or deformity. Commonly used implants like Ti (110-120 GPa) and Co-Cr alloys (200-230 GPa) exhibit high elastic moduli, which can lead to ‘stress shielding’, which is a phenomenon that causes bone to weaken when the implant bears most of the load. In addition, the release of certain metallic ions from these materials can provoke adverse tissue reactions. To combat these drawbacks, medium-entropy alloys (MEAs) provide a variety of advantages in terms of lower elastic modulus (from a single-phase body-centered-cubic structure), improved corrosion resistance, and superior biocompatibility. The surface modification of implant surfaces is highly demanding in conferring bioactive properties to bioinert alloy surfaces. Among the various surface engineering approaches, the hydrothermal technique is highly advantageous in improving osseointegration. However, reports associated with the surface functionalization of MEAs are sparse in the literature. The present work explores the hydrothermal surface modification of Nb₃₀Ti₃₀Zr₃₀Cr₅Mo₅-based MEAs for implant application. This study delves deep into the structural aspects and surface characterization of these MEAs with particular emphasis on X-ray Photoelectron Spectroscopy (XPS) analysis for pertinent implant application. This work holds promising prospects in understanding MEA surfaces and how the obtained information can be used for developing futuristic bioimplant surfaces.

In the last decades, green biomaterials have been explored as alternatives to conventional
petroleum-based polymers for applications in the health and food sectors [1]. Biomass-related
proteins present intriguing biopolymers to be used as sustainable, biocompatible, and
biodegradable building blocks to design innovative coatings and films [2]. Insect-derived proteins
are a promising and novel building block for functional coatings. Hermetia illucens, commonly
known as Black Soldier Fly (BSF), has the ability to convert organic waste into a valuable larval
biomass. The latter is rich in proteins of high biological value and has gained attention mainly as
animal feed [3].
In this contribution, BSF proteins are proposed as raw material for bioplastics due to their film-
forming properties. The preparation of composite films based on BSF protein extract, along with
their spectroscopic and mechanical characterization, is presented.
Protein extraction was performed on defatted BSF larvae powder, using a modified method basedon Caligiani et al. [4]. A critical step for suitable dry-casted film formation was protein solubilization.
The proper combination of sodium dodecyl sulphate (SDS) as surfactant and glycerol as plasticizer
was evaluated based on tensile strength and strain tests.
Infrared characterization demonstrated good film homogeneity. Preliminary experiments on the
incorporation of antimicrobial zinc-based materials [5] for coating preparation were also carried out.
In conclusion, our results demonstrate the potential of BSF proteins as a novel source for bio-based
film preparations, opening the door to their use for diverse technological applications.

1. Q. Lin et al., ACS Biomaterials Science & Engineering 10 (2024) 6751-6765
2. S. Gopalakrishnan et al., Adv. Sustainable Syst. 5 (2021) 2000167.
3. K. B. Barragan-Fonseca et al., Journal of Insects as Food and Feed 3 (2017) 105-120.
4. A. Caligiani et al., Food research international 105 (2018) 812-820.
5. M.C. Sportelli et al., Nanomaterials 10(2020) 473.

Surface engineering plays a key role in enhancing the performance of next-generation titanium-based implantable medical devices. Incorporating bioactive agents into protective coating offers a promising strategy to tailor surface properties to improve biological responses after implantation. This study aims to develop PMMA–silica coatings containing calcium and silver phosphates in the surface layer, acting simultaneously as an anticorrosion barrier and a bioactive layer. PMMA–silica coatings were synthesized by combining the sol–gel process of tetraethylorthosilicate (TEOS) with the radical polymerization of methyl methacrylate (MMA) and 3-methacryloxypropyl trimethoxysilane (MPTS). Bioactive agents, including hydroxyapatite (HA), β-tricalcium phosphate (β-TCP), and silver phosphate (Ag₃PO₄), were dispersed in the PMMA–silica solution. The coatings were deposited onto Ti6Al4V substrates by immersion, resulting in uniform layers with thicknesses of up to 17 µm, free of cracks and exhibiting excellent adhesion strength (>14 MPa). The influence of the additives on the structural properties of the nanocomposites was analyzed using infrared spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, thermal analysis, and contact angle measurements. Electrochemical impedance spectroscopy conducted in simulated body fluid (SBF, ISO 23317) confirmed the excellent anticorrosion performance of the modified coatings, showing an impedance modulus of up to 70 GΩ cm² after 100 days in SBF, which is four orders of magnitude higher than that of uncoated Ti6Al4V. Additionally, apatite crystal deposits observed after 28 days of immersion in SBF are an indicator of the in vivo bone bioactivity of the coatings. Biological evaluations revealed enhanced proliferation of SaOS-2 osteoblasts after 7 days of culture on coatings containing β-TCP or HA combined with Ag₃PO₄. These results highlight the potential of modified PMMA–silica coatings as highly promising materials for improving the bioactive and anticorrosive properties of Ti-based implants.

Acknowledgments: This research received financial support from the Brazilian funding agencies CNPq and CAPES.

Silver-based biomaterials have excellent antimicrobial properties, as shown by experimental studies on bacterial cultures, viruses, and fungi. The properties of silver nanoparticles have attracted attention around the development of materials that efficiently utilize these characteristics. Thus, silver has been incorporated into many medical products, such as anticancer agents, controlled-release systems, coatings for orthopedic materials and medical devices, as well as bandages, etc.

The aim of this study is to simulate the antimicrobial properties of silver coatings and observe the influence of the morphology and thickness of the silver layer on these properties. To achieve this, the variation in time of the silver concentration and the concentration of bacterial cultures in the selected medium (agar in a Petri dish) were monitored. In this study, the diffusion of silver ions through agar and their interaction with Gram-positive (S. aureus, S. epidermidis) and Gram-negative (E. coli, K. pneumoniae) bacterial cultures was simulated.

According to preliminary data, particles with cubic and spherical morphology exhibit the best antimicrobial properties, with a silver concentration above the minimum inhibitory concentration for both Gram-positive and Gram-negative bacteria. These results indicate the applicability of simulations as a preliminary method for determining the optimal parameters for designing materials with medical applications.

Copper, widely recognized for its antimicrobial properties, has proven to be an essential material for reducing environmental contamination and preventing infections. Its antimicrobial action is based on the release of copper ions (Cu⁺ and Cu²⁺), which destroy bacterial membranes and alter proteins and nucleic acids, ultimately resulting in cell death. Compared to other metals such as silver and gold, copper stands out for its high efficacy under various environmental conditions, its sustainability, and its lower cost.

In the hospital setting, copper compounds have been shown to significantly reduce microbial loads on contact surfaces. Notable examples include waiting-room chairs with embedded copper nanoparticles and intravenous pools coated with paints containing copper-structured zeolite particles. In studies conducted in hospital environments, these interventions achieved reductions in viable microorganisms ranging from 50% to 73%, highlighting their effectiveness in preventing healthcare-associated infections, a critical issue in this sector.

Copper-based antimicrobial coatings have also been implemented in confined environments, such as detention cells. In these spaces, where hygiene conditions are limited, surfaces treated with copper-enriched paints achieved bacterial-load reductions ranging from 68% to 87%, including a notable decrease in airborne bacteria. This innovative approach underscores copper's potential to significantly improve sanitary conditions and reduce the spread of infections in environments with challenging maintenance needs.

Moreover, the integration of copper nanoparticles into polymer matrices represents a disruptive advance in the development of antimicrobial materials. These materials not only retain the mechanical properties of the base polymer but also maximize copper’s biocidal effectiveness, providing versatile and durable solutions. In conclusion, copper continues to position itself as a key component in the design of advanced materials. Its applications in coatings, medical devices, and water-treatment systems stand out for their effectiveness and versatility in improving sanitary conditions in critical sectors.

Tricalcium phosphate (TCP)-based nanocoatings are used in orthopedics as a bone substitute to favor osseointegration and vascularization processes. Cobalt ions are able to induce hypoxia and stimulate mesenchymal stem cells (MSCs) to produce the pro-angiogenic factor VEGF. Thus, cobalt-substituted TCP (Co-TCP) coatings, with different amounts of cobalt ions (0, 2, 5, 10 and 15 wt%), were realized through Ionized Jet Deposition.

Morphological and physico-chemical properties of the coatings were analyzed. The influence of deposition parameters, such as deposition temperature and amount of Co ions, on the properties were investigated. Fibroblast cells (L929) were cultured for 24-48 hours with material extracts to test the cytotoxic effects. Then, adhesion and proliferation of MSC directly seeded on the coatings were analyzed with also the evaluation of VEGF secretion, as representative pro-angiogenic factor.

All Co-TCPs could be deposited with a good chemical fidelity with respect to the targets, as observed by FT-IR and EDS analyses. Coatings were formed by globular aggregates. The use of 400°C as deposition temperature permitted us to obtain films with higher roughness and crystallinity degrees. Thus, this condition was used for the subsequent analyses. The films were hydrophilic and stable during medium immersion for up to 7 days. No significant cytotoxic effect was noticed on L929, which proliferated and were metabolically active. MSCs adhered and were able to proliferate from 24h up to 7d in all coatings. However, a lower area covered by MSCs was recorded for 15% Co-TCP coatings, a sign of cytotoxic effects due to the higher amount of Co ions. VEGF secretion by BM-MSCs increased significantly when cells were seeded on a 10% Co-TCP coating.

Based on these results, 5% and 10% Co-TCP coatings can be a possible solution for improving VEGF production, and they appear to be a promising tool for future applications.

Titanium-based materials are commonly used for biomedical applications, especially in the dentistry and orthopedic fields, as they are characterized by a wide spectrum of morphological, compositional, and functional parameters. The intensive development of reliable dental implants relies on certain features such as appropriate mechanical resistance, biocompatibility, and the ability to promote Osseo integration. The aim of the work was the identification of the key parameters for obtaining inorganic and hybrid materials coatings appropriate for biomedical application (i.e. dental implants) with intrinsic antibacterial activity. For this purpose, nanostructured TiO₂ modified with Au/Ag metal nanoparticles and lysozyme, coated on titanium foil was synthesized. Scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD), photoluminescence (PL), and UV–Vis spectroscopies were used to investigate the morphological, structural and functional properties of the resulting coatings. Several paths were studied as follows. Firstly, the singlet oxygen (¹O₂) generation by inorganic coatings exposed to visible light irradiation was carried out. Then, the antibacterial activity of the TiO₂/Ti, Au–TiO₂/Ti, and Ag–TiO₂/Ti was assessed. The lysozyme bioactivity for Micrococcus lysodeicticus, used as microbial substrate, was evaluated after its adsorption on Lys/TiO₂/Ti, Lys/Au–TiO₂/Ti and Lys/Ag–TiO₂/Ti inorganic surfaces. Finally, the enzymatic activity of the hybrids materials for the hydrolysis reaction of a synthetic organic substrate, 4-Methylumbelliferyl_-D-N,N0,N”-triacetylchitotrioside [4-MU-_- (GlcNAc)3], was emphasized by identifying the presence of a fluorescent reaction product, 7-hydroxy-4-metyl coumarin (4-methylumbelliferone)