Natural sepiolite has great potential for application in wound healing, haemostasis and medicines. This paper introduces a versatile solid-state sintering technique for preparing sepiolite-based nanocomposites with enhanced antibacterial properties, and the physical, structural, rheological and antibacterial properties of which were determined to be enhanced. The incorporation of nanosized Ag and metal oxides into sepiolite composites results in a notable improvement in their antibacterial efficacy against Escherichia coli and Staphylococcus aureus in comparison to the unmodified sepiolite. With a low silver content of just 5%, the sepiolite–Ag composite achieves an antibacterial rate of ~100%. Furthermore, the rheological properties exhibited by the sepiolite composites are noteworthy, suggesting their suitability for use in wound-dressing applications due to their exceptional workability. The methodology employed in this research has the potential to offer a viable substitute for the production of economical and effective natural antibacterial nanocomposites.

Essential oils (including carvacrol, CAR) have been used in the medicinal and health field because of their broad-spectrum antibacterial activities. However, the volatility and pungent odor are still the greatest obstacles to wider application. The purpose of the present study was to address those problems by encapsulating the antibacterial CAR in palygorskite (Plg) by integrating it into Pickering emulsions with complex coacervation. The CAR in Pickering emulsion was formed firstly by stabilization with the CAR-modified Plg; then, the emulsion droplets were embedded and fixed in the microcapsule through the subsequent complex coacervation process, which occurred between the quaternary ammonium salt of chitooligosaccharides (HACC) and sodium alginate (SA) via calcium ions. The microcapsules obtained were characterized by Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). The results demonstrated that the microcapsules presented a nearly sphere-like shape with a mean diameter of 3.5 mm but had a porous interior structure. The Plg plays multiple roles in the preparation process, including increasing the emulsion stability, improving the encapsulation efficiency of CAR, and the thermostability of microcapsules. The microcapsules showed remarkable antibacterial properties against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), and inhibition rates toward E. coli and S. aureus reached 100% when the microcapsules were encapsulated with 15 or 20% of CAR, respectively. The microcapsules obtained could be used as antibacterial agents in food preservatives, animal feed, and other health-related consumer products.

The direct application of heavy metal- and quaternary ammonium-based antibacterial agents can cause inconvenience such as irritation, short-term applicability, discoloration of the tissue, and environmental concerns. The immobilization of these agents on montmorillonite (Mnt) was expected to diminish these effects by hindering direct contact of the ions with the target tissues. The objective of the present study was, therefore, to prepare inorgano(I)- and organo(O)-montmorillonites (I/O-Mnt) and to determine their potential uses in such biomedical applications. Na-montmorillonite (Mnt-Na) was modified by hydrothermal and microwave irradiation methods using Cu2+/Zn2+, and quaternary ammonium and/or anionic surfactants. The effect of the structures formed by immobilization on Mnt surfaces on antibacterial activity was investigated. Quaternary ammonium surfactants were cetyltrimethyl ammonium bromide (CTAB) with a linear alkyl chain, cetylpyridinium chloride (CPC) with a single aromatic ring, and benzethonium chloride (BZT) with double aromatic rings. N-lauroyl sarcosinate (SR) was the anionic surfactant. The samples were subjected to thermogravimetric (TGA) and scanning electron microscopy (SEM) analyses. Desorption tests showed that the antibacterial efficacy against Streptococcus mutans stemmed from I/O-Mnt and not from the ions released from the material surfaces to the aqueous phase. The results of the antibacterial studies showed that the existence of a linear alkyl chain and a double aromatic ring were the structural factors causing the greatest antibacterial effect. The time-kill tests revealed that Mnt-CTA, Mnt-BZT, and Mnt-CP-SR were effective against Streptococcus mutans within 5 min of contact. With the new findings, they were identified as possible selective and potent bactericidal agents and promising candidates for biomedical applications.

Contamination by bacterial biofilms has a strong negative impact, especially on the surface of prostheses, implants, pins, and other medical-surgical devices. To prevent their formation, one of the alternatives is the modification of the metal surface incorporating silver by low-energy ion implantation, thus avoiding initial bacteria adhesion to the modified surface and further development of the biofilm. The bactericidal properties of silver atoms incorporated on commercially pure titanium surfaces by low-energy ion implantation (4 keV) were evaluated. The surface modifications were analyzed by Rutherford backscattering spectrometry, glow discharge-optical emission spectroscopy, contact angle measure, optical profilometry, and X-ray photoelectron spectroscopy. The microbiological assays were conducted by using Escherichia coli (E. coli). The results demonstrated a reduction on bacterial counting. No toxic effect of silver was detected on human MG-63 cells. The choice of parameters to obtain a bactericidal and nontoxic biomaterial for human cells should consider the ideal combination “energy + silver concentration”. Therefore, it can be considered for industrial application.