This paper reports the results of the PLGA–TiO2 nanocomposite regarding the green synthesis of titanium dioxide nanoparticles using a natural extract, its characterization, and encapsulation with poly(lactic-co-glycolic acid) (PLGA). UV–visible spectrometry was used for the identification of terpenes present in the extracts. The morphology of the nanoparticles was determined by scanning electron microscopy. Infrared spectroscopy was used for the determination of functional groups, while X-ray diffraction was used to determine the crystal structure. The analysis of the extended release of the encapsulated extract in the matrix of the nanomaterial resulted in a maximum visible UV absorbance at approximately 260 nm and confirmed the synthesis of titanium dioxide nanoparticles. Moreover, terpenes enhance synthesis and stabilize titanium dioxide nanoparticles. The synthesized structures are spherical and amorphous, 44 nm in size, and encapsulated at 65 nm.

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The effect of Co into the titanium oxide matrix as photocatalysts in the generation of hydrogen from water is herein reported. Ti–Co mixed oxides and pure titania were synthetized by sol-gel. The Co content was 0, 1, 3, 5, and 10 wt.%. The solids were characterized by Scanning electron microscope-energy dispersive spectrometer (SEM-EDS), N2 physisorption, X-ray difrraction (XRD), ultraviolet visible spectroscopy (UV–Vis), spectroscopy Raman, X-ray photoelectron spectroscopy (XPS) spectroscopy and High resolution transmission electron microscope (HRTEM). The results showed that the mixed oxides show larger specific surface areas (73–186 m2/g) compare to that of pure TiO2 (64 m2/g). The XRD patterns of the Ti-Co samples resemble that of anatase and segregation of Co was not observed by this technique. The band gap energies of these solids vary from 3.05 to 2.85 eV which are smaller than that of pure TiO2 (3.2 eV). The Ti-Co oxides showed an enhancement in the hydrogen production (∼3056 μmol/h) compare to that of TiO2 (190 μmol/h) when using UV light. Furthermore, the photocatalytic activity of titania (110 μmol/h) for this reaction was also smaller than those observed for the Ti-Co mixed oxides (∼4056 μmol/h) under visible light.

This study aimed to develop Ca2+ doped ZnO nanoparticles (NPs) and investigate their antibacterial properties against microorganisms of dental interest. Zn-Ca NPs were synthesized by the sol-gel method with different concentrations of Ca2+ (1, 3, and 5 wt. %) and subsequently characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), UV-vis spectroscopy and Fourier transform infrared spectroscopy (FT-IR). The Kirby–Bauer method was used to measure antibacterial effects. NPs showed the wurzite phase of ZnO and bandgap energies (Eg) from 2.99 to 3.04 eV. SEM analysis showed an average particle size of 80 to 160 nm. The treatments that presented the best antibacterial activity were Zn-Ca 3% and Zn-Ca 5%. ZnO NPs represent an alternative to generate and improve materials with antibacterial capacity for dental applications.

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