Weibull β value for the discernment of drug release mechanism of PLGA particles

Mathematical models are used to characterize and optimize drug release in drug delivery systems (DDS). One of the most widely used DDS is the poly(lactic-co-glycolic acid) (PLGA)-based polymeric matrix owing to its biodegradability, biocompatibility, and easy manipulation of its properties through the manipulation of synthesis processes. Over the years, the Korsmeyer-Peppas model has been the most widely used model for characterizing the release profiles of PLGA DDS. However, owing to the limitations of the Korsmeyer-Peppas model, the Weibull model has emerged as an alternative for the characterization of the release profiles of PLGA polymeric matrices. The purpose of this study was to establish a correlation between the n and β parameters of the Korsmeyer-Peppas and Weibull models and to use the Weibull model to discern the drug release mechanism. A total of 451 datasets describing the overtime drug release of PLGA-based formulations from 173 scientific articles were fitted to both models. The Korsmeyer-Peppas model had a mean Akaike Information Criteria (AIC) value of 54.52 and an n value of 0.42, while the Weibull model had a mean AIC of 51.99 and a β value of 0.55, and by using reduced major axis regression values, a high correlation was found between the n and β values. These results demonstrate the ability of the Weibull model to characterize the release profiles of PLGA-based matrices and the usefulness of the β parameter for determining the drug release mechanism.

Mechanisms of Metallic Nanomaterials to Induce an Antibacterial Effect

Pathogenic microorganisms, including bacteria, are becoming resistant to most existing drugs, which increases the failure of pharmacologic treatment. Therefore, new nanomaterials were studied to spearhead improvement against the same resistant pathogenic bacteria. This has increased the mortality in the world population, principally in under-developed countries. Moreover, recently there has been research to find new drug formulations to kill the most dangerous microorganisms, such as bacteria cells which should avoid the spread of disease. Therefore, lately, investigations have been focusing on nanomaterials because they can exhibit the capacity to show an antibacterial effect. These studies have been trying oriented in their ability to produce an improvement to get antibacterial damage against the same pathogenic bacteria resistance. However, there are many problems with the use of nanoparticles. One of them is understanding how they act against bacteria, "their mechanism(s) action" to induce reduction or even kill the bacterial strains. Therefore, it is essential to understand the specific mechanism(s) of each nanomaterial used to observe the interaction between bacteria cells and nanoparticles. In addition, since nanoparticles can be functionalized with different antibacterial drugs, it is necessary to consider and distinguish the antibacterial activity of the nanoparticles from the antibacterial activity of the drugs to avoid confusion about how the nanoparticles work. Knowledge of these differences can help better understand the applications of the primary nanoparticles (i.e., Ag, Au, CuO, ZnO, and TiO², among others) described in detail in this review which are toxic against various bacterial strains.

Study of the Interaction of Ti-Zn as a Mixed Oxide at Different pH Values Synthesized by the Sol-Gel Method and Its Antibacterial Properties

TiO2, ZnO, and their combination (TiO2−ZnO) at different molar ratios and pH values (Ti−Zn A and B 3:1, 1:1, and 1:3) via the sol−gel method were characterized by SEM, XRD, UV-Vis, and FT-IR. Moreover, antibacterial tests of the nanoparticles were conducted against Escherichia coli (E. coli), Salmonella paratyphi (S. paratyphi), Staphylococcus aureus (S. aureus), and Listeria monocytogenes (L. monocytogenes). The indirect bandgap of the Ti−Zn binary oxide synthesized in the basic process at molar ratios of 3:1, 1:1, and 1:3 exhibited a higher eV (3.31, 3.30, and 3.19 eV, respectively) compared to pure TiO2 (3.2 eV) and synthesized in the acid process (3.22, 3.29, and 3.19 eV at same molar ratio, respectively); in addition, the results of the indirect bandgap were interesting due to a difference found by other authors. Moreover, the sol−gel method promoted the formation of a spherical, semi-sphere, and semi-hexagonal shape (TiO2, Ti−Zn 1:1, and Ti−Zn 1:3) with a size ≤ 150 nm synthesized during the acid process, with a crystallite size of ~71, ~12, ~34, and ~21 nm, respectively, while ZnO NPs developed a hexagonal and large size (200−800 nm) under the same synthesis process (acid). Samples were classified as TiO2 anatase phase (basic synthesis); however, the presented changes developed in the rutile phase (24% rutile phase) at an acid pH during the synthesis process. Moreover, Ti−Zn maintained the anatase phase even with a molar ratio of 1:3. The most interesting assessment was the antibacterial test; the Ti−Zn A (1:3) demonstrated a bacteriostatic effect compared with all treatments except ZnO, which showed a similar effect in dark conditions, and only Gram-positive bacteria were susceptible (Listeria monocytogenes > Staphylococcus aureus). Therefore, the Ti−Zn characteristic suggests that the results have potential in treating wastewater as well as in pharmaceutical (as drug carriers) and medical applications.

Review of therapies using TiO2 nanomaterials for increased anticancer capability

Recently, Titanium dioxide (TiO2) has been studied as an alternative to treat cancer diseases under different activation therapies. The aim of this review was to describe the effect of TiO2 nanoparticles (NPs) on some cancer cell lines and their interaction with phototherapies such as photodynamic therapy (PDT), photothermal therapy (PTT), sonodynamic therapy (SDT), and ultraviolet therapy (UV) for anticancer treatment. The use of TiO2 combined with PDT, PTT, SDT, or UV has shown a remarkable capacity to enhance the killing of cancer cells through reactive oxygen species formation. Thus, the combination of TiO2 and activation therapies exhibited great potential and could be a viable anticancer treatment strategy. However, more studies on phototherapies in combination with TiO2 and their effects at under different experimental conditions (TiO2 concentration, type of cancer cells, and intensity and frequency of therapies) are necessary to guarantee the safe use of this kind of therapy.