Publications by authors named "María Paulina Romero"

3 Publications

  • Page 1 of 1

One-Pot Microwave-Assisted Synthesis of Carbon Dots and and Antimicrobial Photodynamic Applications.

Front Microbiol 2021 21;12:662149. Epub 2021 Jun 21.

São Carlos Institute of Physics, University of São Paulo, São Carlos, Brazil.

Carbon-based photosensitizers are more attractive than the other ones based on their low cost, high stability, broadband of light absorption, tunable emission spectra, high quantum yield, water solubility, high resistance to metabolic degradation, and selective delivery. These properties allow multiple applications in the field of biology and medicine. The present study evaluated and the antimicrobial photodynamic effect of a one-pot microwave produced C-DOTS based on citric acid. The assays assessed the effectiveness of illuminated C-DOTS (C-DOTS + light) against suspension and biofilm. The concentrations of 6.9 and 13.8 mg/mL of C-DOTS and light doses of 20 and 40 J/cm were able to reduce significantly the microorganisms. Based on these parameters and results, the experiments were conducted in mice, evaluating this treatment on wounds contaminated with The viability test showed that C-DOTS-mediated photodynamic inactivation reduced 10 log of the bacteria present on the skin lesions. These results, altogether, showed that antibacterial photodynamic therapy using C-DOTS is a promising and viable treatment for Gram-positive bacteria-infected wounds.
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http://dx.doi.org/10.3389/fmicb.2021.662149DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8255795PMC
June 2021

Graphene Oxide Mediated Broad-Spectrum Antibacterial Based on Bimodal Action of Photodynamic and Photothermal Effects.

Front Microbiol 2019 15;10:2995. Epub 2020 Jan 15.

São Carlos Institute of Physics, University of São Paulo, São Carlos, Brazil.

Graphene oxide (GO) with their interesting properties including thermal and electrical conductivity and antibacterial characteristics have many promising applications in medicine. The prevalence of resistant bacteria is considered a public health problem worldwide, herein, GO has been used as a broad spectrum selective antibacterial agent based on the photothermal therapy (PTT)/photodynamic therapy (PDT) effect. The preparation, characterization, determination of photophysical properties of two different sizes of GO is described. light dose and concentration-dependent studies were performed using Gram-negative and Gram-positive bacteria based on the PTT/PDT effect used ultra-low doses (65 mW cm) of 630 nm light, to achieve efficient bacterial decontamination. The results show that GO and nanographene oxide (nGO) can sensitize the formation of O and allow a temperature rise of 55°C to 60°C together nGO and GO to exert combined PTT/PDT effect in the disinfection of gram-positive and gram-negative bacteria. A complete elimination of and bacteria based on GO and nGO is obtained by using a dose of 43-47 J cm for high concentration used in this study, and a dose of around 70 J cm for low dose of GO and nGO. The presence of high concentrations of GO allows the bacterial population of and to be more sensitive to the use of PDT/PTT and the efficiency of and bacteria disinfection in the presence of GO is similar to that of nGO. In human neonatal dermal fibroblast, HDFs, no significant alteration to cell viability was promoted by GO, but in nGO is observed a mild damage in the HDFs cells independent of nGO concentration and light exposure. The unique properties of GO and nGO may be useful for the clinical treatment of disinfection of broad-spectrum antimicrobials. The antibacterial results of PTT and PDT using GO in gram-positive and gram-negative bacteria, using low dose light, allow us to conclude that GO and nGO can be used in dermatologic infections, since the effect on human dermal fibroblasts of this treatment is low compared to the antibacterial effect.
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http://dx.doi.org/10.3389/fmicb.2019.02995DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6974586PMC
January 2020

Physiological considerations acting on triplet oxygen for explicit dosimetry in photodynamic therapy.

Photodiagnosis Photodyn Ther 2017 Sep 25;19:298-303. Epub 2017 Jul 25.

Departamento de Física, Facultad de Ciencias, Escuela Politécnica Nacional, Quito, Ecuador.

The aims of this study were to determine the spatial and temporal theoretical distribution of the concentrations of Protoporphyrin IX, O and doses of O. The type II mechanism and explicit dosimetry in photodynamic therapy were used. Furthermore, the mechanism of respiration and cellular metabolism acting on O were taken into account. The dermis was considered as an absorbing and a scattering medium. An analytical solution was used for light diffusion in the skin. The photophysical, photochemical and biological effects caused by PDT with the initial irradiances of 20, 60 and 150mW/cm were studied for a time of exposure of 20min and a maximum depth of 0.5cm. We found that the initial irradiance triples its value in 0.02cm and that almost 100% of PpIX is part of the dynamics of reactions in photodynamic therapy. Additionally, with about 40μMof O there is a balance between the consumed and supplied oxygen. Finally, we determined that with 60mW/cm, the highest dose of O is obtained.
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http://dx.doi.org/10.1016/j.pdpdt.2017.07.008DOI Listing
September 2017
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