Publications

The growing threat of antibiotic-resistant pathogens has intensified the demand for alternative antibacterial materials. Quatsomes-nanovesicles composed of cholesterol and quaternary ammonium surfactants (QAS)- emerge as promising candidates due to their intrinsic antimicrobial properties and tunable physicochemical characteristics. Here, we investigate the antibacterial activity of quatsomes incorporating QAS with either tetradecyl (C14) or hexadecyl (C16) alkyl chains against Staphylococcus aureus, a leading cause of hospital-acquired infections. Both quatsome types exhibited potent bactericidal activity in planktonic cultures, with C16containing formulations showing a 2.5-fold lower minimum bactericidal concentration than C14 counterparts. Confocal microscopy suggested a partial penetration of cationic quatsomes into the bacterial peptidoglycan layer, accompanied by significant increases in zeta-potential, suggesting strong electrostatic interactions without visible membrane disruption, as confirmed by scanning electron microscopy. Both formulations also demonstrated high efficacy against mature S. aureus biofilms, with no significant differences between alkyl chain lengths, indicating a mechanism primarily targeting the extracellular biofilm matrix. In addition, they showed a good antimicrobial activity against methicillin-resistant Staphylococcus aureus (MRSA). A preliminary safety assessment using reconstructed human epidermis (EpiskinTM) confirmed the non-irritant nature of both formulations. These findings highlight the potential of QAS-based quatsomes as effective and biocompatible nanocarriers for topical antibacterial applications, offering a promising platform for combating antibiotic-resistant infections in both planktonic and biofilm states.

JTD Keywords: Antibacterial materials, Antimicrobial activity, Biofilm, Gram-positive bacteria, Growth, Nanovesicles, Quaternary ammonium surfactants, Quatsomes, Silver nanoparticles, Staphylococcus aureus

Nature has inspired the creation of artificial micro- and nanomotors that self-propel converting chemical energy into mechanical action. These tiny machines have appeared as promising biomedical tools for treatment and diagnosis and have also been used for environmental, antimicrobial or sensing applications. Among the possible catalytic engines, enzymes have emerged as an alternative to inorganic catalysts due to their biocompatibility and the variety and bioavailability of fuels. Although the field of enzyme-powered micro- and nano-motors has a trajectory of more than a decade, a comprehensive framework on how to rationally design, control and optimize their motion is still missing. With this purpose, herein we performed a thorough bibliographic study on the key parameters governing the propulsion of these enzyme-powered devices, namely the chassis shape, the material composition, the motor size, the enzyme type, the method used to incorporate enzymes, the distribution of the product released, the motion mechanism, the motion media and the technique used for motion detection. In conclusion, from the library of options that each parameter offers there needs to be a rational selection and intelligent design of enzymatic motors based on the specific application envisioned.

JTD Keywords: Catalase, Hydrogen-peroxide, Micro/nanomotors, Micromotors, Movement, Nanomotors, Propulsion, Surfactants, Therapy, Tumor microenvironment

The present investigation reports the development of PEG-modified liposomes for the delivery of naturally occurring resveratrol. PEG-modified liposomes were prepared by direct sonication of the phospholipid aqueous dispersion, in the presence of two PEG-surfactants. Small, spherical, unilamellar vesicles were produced, as demonstrated by light scattering, cryo-TEM, and SAXS. The aging of the vesicles was assessed by using the Turbiscan® technology, and their physical stability was evaluated in vitro in simulated body fluids, results showing that the key features of the liposomes were preserved. The biocompatibility of the formulations was demonstrated in an ex vivo model of hemolysis in human erythrocytes. Further, the incorporation of resveratrol in PEG-modified liposomes did not affect its intrinsic antioxidant activity, as DPPH radical was almost completely inhibited, and the vesicles were also able to ensure an optimal protection against oxidative stress in an ex vivo human erythrocytes-based model. Therefore, the proposed PEG-modified liposomes, which were prepared by a simple and reliable method, represent an interesting approach to safely deliver resveratrol, ensuring the preservation of the carrier structural integrity in the biological fluids, and the antioxidant efficacy of the polyphenol to be exploited against oxidative stress associated with cancer.

JTD Keywords: Resveratrol, Antioxidant, PEG-surfactants, PEG-modified liposomes, Human erythrocytes