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Authors
Abstract(s)
A presente dissertação teve como principal objetivo a síntese sustentável de nanopontos de carbono (NPsC) luminescentes e bioativos, utilizando como fonte de carbono resíduos sólidos do tomate (RST) e a sua posterior aplicação como agentes antimicrobianos e marcadores celulares fluorescentes. Após a síntese por carbonização hidrotérmica através de aquecimento convencional e radiação micro-ondas, e subsequentes etapas de isolamento e purificação, os NPsC foram caracterizados estruturalmente por espetroscopia de infravermelho com transformada de Fourier (FTIR), ressonância magnética nuclear de protão (RMN 1H) e análise elementar. A avaliação das propriedades fotofísicas dos nanomateriais foi realizada por espetroscopia de absorção no estado fundamental (UV-Vis) e espetroscopia de fluorescência no estado estacionário. A bioatividade dos NPsC foi estudada in vitro através da determinação das suas propriedades antioxidantes e da avaliação da sua atividade antimicrobiana contra bactérias Gram--negativas (Escherichia coli) e Gram-positivas (Staphylococcus aureus) pelos métodos de difusão em disco e de microdiluição em meio líquido. Os NPsC atuaram de forma não seletiva nas bactérias em estudo, tendo os nanomateriais sintetizados com radiação micro--ondas exibido atividade antibacteriana superior. A análise in vitro do efeito citotóxico foi realizada através da avaliação da viabilidade de linhas celulares animais e humanas selecionadas, evidenciando a generalidade dos NPsC toxicidade reduzida, que aliada à capacidade de marcação por fluorescência permitiu a identificação de diversas regiões celulares. Estas caraterísticas associadas à sua emissão sintonizável, reforçam o potencial de utilização destes novos nanomateriais em marcação celular.
The main objective of this dissertation was the sustainable synthesis of luminescent and bioactive carbon nanopots (CNDs) using solid tomato waste (STW) as carbon source, and their subsequent application as antimicrobial agents and fluorescent cell markers. After synthesis by hydrothermal carbonization using conventional heating and microwave--assisted irradiation, and subsequent isolation and purification steps, the CNDs were structurally characterized using Fourier transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance (1H NMR) and elemental analysis. The photophysical properties of the nanomaterials were evaluated using ground-state absorption spectroscopy (UV-Vis) and steady-state fluorescence spectroscopy. The bioactivity of the CNDs was studied in vitro by determining their antioxidant properties and assessing their antimicrobial activity against Gram-negative (Escherichia coli) and Gram--positive (Staphylococcus aureus) bacteria using the disk diffusion and broth microdilution methods. The CNDs exhibited non-selective activity against the studied bacteria, with nanomaterials synthesized through microwave-assisted radiation displaying superior antibacterial activity. The in vitro analysis of the cytotoxic effect was carried out by assessing the viability of selected animal and human cell lines, showing that the CNDs were generally low in toxicity,which, together with their fluorescence labelling capacity, enabled the identification of various cell regions. These characteristics, associated with their tunable emission, reinforce the potential for the using of these new nanomaterials in cell labelling.
The main objective of this dissertation was the sustainable synthesis of luminescent and bioactive carbon nanopots (CNDs) using solid tomato waste (STW) as carbon source, and their subsequent application as antimicrobial agents and fluorescent cell markers. After synthesis by hydrothermal carbonization using conventional heating and microwave--assisted irradiation, and subsequent isolation and purification steps, the CNDs were structurally characterized using Fourier transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance (1H NMR) and elemental analysis. The photophysical properties of the nanomaterials were evaluated using ground-state absorption spectroscopy (UV-Vis) and steady-state fluorescence spectroscopy. The bioactivity of the CNDs was studied in vitro by determining their antioxidant properties and assessing their antimicrobial activity against Gram-negative (Escherichia coli) and Gram--positive (Staphylococcus aureus) bacteria using the disk diffusion and broth microdilution methods. The CNDs exhibited non-selective activity against the studied bacteria, with nanomaterials synthesized through microwave-assisted radiation displaying superior antibacterial activity. The in vitro analysis of the cytotoxic effect was carried out by assessing the viability of selected animal and human cell lines, showing that the CNDs were generally low in toxicity,which, together with their fluorescence labelling capacity, enabled the identification of various cell regions. These characteristics, associated with their tunable emission, reinforce the potential for the using of these new nanomaterials in cell labelling.
Description
Trabalho final de Mestrado para obtenção do grau de Mestre em Engenharia Química e Biológica – Perfil de Processos Químicos
Keywords
Nanopontos de carbono Resíduos sólidos do tomate Carbonização hidrotérmica Fluorescência Bioatividade Citotoxicidade Carbon nanodots Solid tomato waste Hydrothermal carbonization Fluorescence Bioactivity Cytotoxicity
Pedagogical Context
Citation
ANTUNES, Bruno Guerreiro - Síntese sustentável de nanomateriais de carbono fluorescentes e bioativos a partir de desperdícios da indústria do tomate. Lisboa: Instituto Superior de Engenharia de Lisboa, 2023. Dissertação de Mestrado.