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Conjugation of photosensitizers (PS) with nanoparticles has been largely used as a strategy to stabilize PS in the biological medium resulting in photosensitizing nanoparticles of enhanced photoactivity. Herein, (Meso-5, 10, 15, 20-tetrakis (3-hydroxyphenyl) phorphyryn (mTHPP) was conjugated with diamond nanoparticles (ND) by covalent bond. Nanoconjugate ND-mTHPP showed suitable stability in aqueous suspension with 58 nm of hydrodynamic diameter and Zeta potential of −23 mV. The antibacterial activity of ND-mTHPP was evaluated against Escherichia coli for different incubation times (0–24 h). The optimal activity was observed after 2 h of incubation and irradiation (660 nm; 51 J/cm2) performed right after the addition of ND-mTHPP (100 μg/mL) to the bacterial suspension. The inhibitory activity was 56% whereas ampicillin at the same conditions provided only 14% of bacterial growth inhibition. SEM images showed agglomerate of ND-mTHPP adsorbed on the bacterial cell wall, suggesting that the antimicrobial activity of ND-mTHPP was afforded by inducing membrane damage. Cytotoxicity against murine embryonic fibroblast cells (MEF) was also evaluated and ND-mTHPP was shown to be noncytotoxic since viability of cells cultured for 24 h in the presence of the nanoconjugate (100 μg/mL) was 78%. Considering the enhanced antibacterial activity and the absence of cytotoxic effect, it is possible to consider the ND-mTHPP nanoconjugate as promising platform for application in antimicrobial photodynamic therapy (aPDT).

Aiming to produce an antimicrobial dressing for wound healing applications, in this work Tea Tree oil (TTO) was incorporated into PHBV nanofibers by absorption. It was observed increase in the nanofiber diameter due to 5% TTO absorption efficiency, which also led to a 54% decrease in the contact angle. The releasing assay indicates a 6.8% oil release in the first 24 h -being probably the oil deposited at the polymer surface -followed by a minimal release at 48 h. The set of antimicrobial assays performed suggests the incorporation of TTO optimized the antimicrobial activity of the polymer for E. coli and C. albicans, while against S. aureus no significant difference was observed. The MTT assay showed no cytotoxicity of PHBV, but the incubation of L929 fibroblast cells with PHBV-TTO reduced cell viability. Overall, the PHBV nanofibers containing TTO present great potential as an antimicrobial dressing.

Wastes management studies concerning slaker grits, a rich calcium carbonate landfilled residue from the pulp and paper industry, are focused on their application in the construction field due to their calcareous nature. To the best of our knowledge, slaker grits addition in a high calcium content ceramic frit formulation and their behavior as a glaze has not yet been explored, being the aim of this work. Grits were added as a calcium oxide source in 0, 50%, and 100%, and the frits were analyzed regarding their chemical composition, devitrification, sintering behavior, morphology, colorimetric coordinates, and scratch resistance. By means of comparison, the commercial frit was also characterized. The glazes were analyzed by their physical and thermal properties and scratch resistance. Grits did not prevent the vitreous phases obtention and, compared to the commercial frit, presented a similar behavior, although resulted in higher wollastonite devitrification that directly affected glazes' thermal properties, sintering contraction, linear thermal expansion coefficient, among others. A great outcome was the quartz scratch resistance of the glaze containing the highest grits content, revealing an optimized behavior. Grits residue proved to be a promising alternative raw material capable of generating sustainable and economic perspectives for the ceramic coating sector.

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