The inappropriate use of antimicrobials has resulted in the selection of resistant strains. Thus, a great number of studies have focused on the investigation of new antimicrobial agents. The use of zinc oxide nanoparticles (ZnO NPs) to optimise the fight against microbial resistance has been receiving increased attention due to the non-specific activity of inorganic antimicrobial agents. The small particle size and the high surface area of ZnO NPs can enhance antimicrobial activity, causing an improvement in surface reactivity. In addition, surface modifiers covering ZnO NPs can play a role in mediating antimicrobial activity since the surface properties of nanomaterials alter their interactions with cells; this may interfere with the antimicrobial effect of ZnO NPs. The possibility of using surface modifiers with groups toxic to microorganisms can improve the antimicrobial activity of ZnO NPs. Understanding the exact toxicity mechanisms is crucial to elucidating the antimicrobial activity of ZnO NPs in bacteria and fungi. Therefore, this review aims to describe the mechanisms of ZnO NPs toxicity against fungi and bacteria and how the different structural and physical-chemical characteristics of ZnO NPs can interfere in their antimicrobial activity.

Pharmaceutical design has enabled important advances in the prevention, treatment, and diagnosis of diseases. The use of nanotechnology to optimize the delivery of drugs and diagnostic molecules is increasingly receiving attention due to the enhanced efficiency provided by these systems. Understanding the structures of nanocarriers is crucial in elucidating their physical and chemical properties, which greatly influence their behavior in the body at both the molecular and systemic levels. This review was conducted to describe the principles and characteristics of techniques commonly used to elucidate the structures of nanocarriers, with consideration of their size, morphology, surface charge, porosity, crystalline arrangement, and phase. These techniques include X-ray diffraction, small-angle X-ray scattering, dynamic light scattering, zeta potential, polarized light microscopy, transmission electron microscopy, scanning electron microcopy, and porosimetry. Moreover, we describe some of the commonly used nanocarriers (liquid crystals, metal–organic frameworks, silica nanospheres, liposomes, solid lipid nanoparticles, and micelles) and the main aspects of their structures.

Nowadays, concern over skin cancer has been growing more and more, especially in tropical countries where the incidence of UVA/B radiation is higher. The correct use of sunscreen is the most efficient way to prevent the development of this disease. The ingredients of sunscreen can be organic and/or inorganic sun filters. Inorganic filters present some advantages over organic filters, such as photostability, non-irritability and broad spectrum protection. Nevertheless, inorganic filters have a whitening effect in sunscreen formulations owing to the high refractive index, decreasing their esthetic appeal. Many techniques have been developed to overcome this problem and among them, the use of nanotechnology stands out. The estimated amount of nanomaterial in use must increase from 2000 tons in 2004 to a projected 58000 tons in 2020. In this context, this article aims to analyze critically both the different features of the production of inorganic filters (synthesis routes proposed in recent years) and the permeability, the safety and other characteristics of the new generation of inorganic filters.

This is a review of hybrid materials based on silica as an inorganic phase used as drug delivery systems (DDS). Silica based DDS have shown effectivity when compared with traditional delivery systems. They present advantages such as: (a) ability to maintain the therapeutic range with minor variations; (b) prevention of local and systemic toxic effects; (c) plasma concentrations increase of substances with a short half-life; and (d) reduction of the number of daily doses, which may increase patient adherence to the treatment. These advantages occur due to the physical, chemical and optical properties of these materials. Therefore, we discuss the properties and characteristics of them and we present some applications, using different approaches of DDS to ensure therapeutic effectiveness and side effects reduction such as implantable biomaterial, film-forming materials, stimuli-responsive systems and others.

Nanocrystals of ZnO are currently attracting great interest as potential labels for biological applications, such as theranostic devices, due to their luminescent properties and low toxicity in vivo. It has been reported that doping with Mg ²⁺ ions could enhance the luminescence of ZnO quantum dots (QDs). In the present study Mg-doped ZnO QDs were synthesized by a hydrolysis and condensation reaction. Surface modification of the QDs was performed using oleic acid (OA) to hinder their aggregation and to provide them colloidal stability in non-polar environments. Mg ²⁺ ions could be incorporated into the ZnO wurtzite lattice owing to the very close values of the Mg ²⁺ and Zn ²⁺ ion radii. However, the dopant ions strongly influenced the growth and final size of ZnO nanocrystals, as evidenced by time-resolved synchrotron SAXS measurements. The presence of Mg prevented the aggregation of the primary nanoparticles. Doping with Mg ²⁺ ions widened the band gap of ZnO QDs and enhanced their visible luminescence. With increasing proportion of Mg ²⁺ ions, both the absorption and emission spectra experienced a blue shift. The luminescence went through a maximum for a 20 mol% nominal concentration of Mg ²⁺ ions in the reaction medium. The quantum yield (QY) of 20 mol% Mg-doped ZnO colloidal suspension (64%) was about 6 times higher than that of the ZnO suspension (10%). Mg-doped ZnO QDs capped by OA formed stable colloidal dispersions in chloroforme, with strong visible fluorescence (QY=38%), promising for biological imaging.

Nanoparticles as drug delivery systems and diagnostic agents have gained much attention in recent years, especially for cancer treatment. Nanocarriers improve the therapeutic efficiency and bioavailability of antitumor drugs, besides providing preferential accumulation at the target site. Among different types of nanocarriers for drug delivery assays, metal-organic frameworks (MOFs) have attracted increasing interest in the academic community. MOFs are an emerging class of coordination polymers constructed of metal nodes or clusters and organic linkers that show the capacity to combine a porous structure with high drug loading through distinct kinds of interactions, overcoming the limitations of traditional drug carriers explored up to date. Despite the rational design and synthesis of MOFs, structural aspects and some applications of these materials like gas adsorption have already been comprehensively described in recent years; it is time to demonstrate their potential applications in biomedicine. In this context, MOFs can be used as drug delivery systems and theranostic platforms due to their ability to release drugs and accommodate imaging agents. This review describes the intrinsic characteristics of nanocarriers used in cancer therapy and highlights the latest advances in MOFs as anticancer drug delivery systems and diagnostic agents.