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Resumo(s)
O presente trabalho final de mestrado teve como principal objetivo a valorização de resíduos agrícolas, nomeadamente ouriços da castanha (OsC), na síntese sustentável de nanopontos de carbono (NPsC), nanopartículas com propriedades luminescentes e biológicas, com grande potencial na área da biomédica, sobretudo ao nível da imagem médica. A síntese dos NPsC foi realizada via carbonização hidrotérmica com aquecimento convencional (CHAC) dos OsC. A caraterização físico-química dos OsC e os métodos de síntese utilizados na obtenção dos NPsC serão apresentados e discutidos ao longo desta dissertação. De modo a estabelecer as melhores condições de síntese, tendo em vista aprimorar as propriedades óticas e biológicas dos NPsC, efetuou-se um design fatorial 23, identificando-se como fatores significantes a natureza do aditivo, o tempo de reação e o rácio mássico aditivo/OsC. A caracterização estrutural dos NPsC sintetizados foi estabelecida por espetroscopia de infravermelho com transformada de Fourier (FTIR), ressonância magnética de protão (RMN 1H) e análise elementar (AE) e a sua caracterização morfológica foi avaliada por microscopia de força atómica (AFM). As propriedades fotofísicas recorreram à utilização de espetroscopia de absorção no estado fundamental (UV-Vis) e luminescência de estado estacionário. Foi também determinado o tempo de vida e o potencial dos NPsC. Foram exploradas in vitro algumas propriedades biológicas dos NPsC, nomeadamente a sua atividade antioxidante, pelo método do radical ABTS e a atividade anti-inflamatória, pelo método da inibição da desnaturação de proteína, bem como a sua atividade antibacteriana contra bactérias Gram-positivas (Staphylococcus aureus) e Gram-negativas (Escherichia coli), pelo método da difusão em disco. Avaliou-se ainda a sua citotoxicidade in vitro e in vivo recorrendo a linhas celulares animais tumorais (S180, HeLa) e não tumorais (VERO, NIH-3T3). A citotoxicidade in vivo foi avaliada utilizando o microcrustáceo Artemia salina como organismo modelo, tendo sido observada por microscopia de fluorescência a internalização dos NPsC.
Abstract The main objective of this master's thesis was to valorize agricultural waste, namely chestnut husks (CNHs), in the sustainable synthesis of carbon nanodots (CNDs), nanoparticles with luminescent and biological properties, with great potential in the biomedical field, especially in medical imaging. The synthesis of CNDs was carried out via hydrothermal carbonization with conventional heating (HCCH) of CNHs. The physical-chemical characterization of CNHs and the synthesis methods used to obtain CNDs will be presented and discussed throughout this dissertation. To establish the optimal synthesis conditions for enhancing the optical and biological properties of CNDs, a 23 factorial design was employed. This analysis revealed that the significant factors in the CNDs synthesis are the nature of the additive, the reaction time, and the additive/CNHs ratio. The structural characterization of the synthesized CNDs was established by Fourier transform infrared spectroscopy (FTIR), proton magnetic resonance (1H NMR), and elemental analysis (EA), and their morphological characterization was evaluated by atomic force microscopy (AFM). The photophysical properties were determined using fundamental state absorption spectroscopy (UV-Vis) and steady-state luminescence. The lifetime and potential of the CNDs were also determined. The biological properties of the CNDs were explored in vitro, including their antioxidant activity, assessed using the ABTS radical method; their anti-inflammatory potential, evaluated through the inhibition of protein denaturation; and their antibacterial activity against Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria, determined by the disc diffusion method. The cytotoxicity of the CNDs was also evaluated in vitro using tumor (S180, HeLa) and non-tumor (VERO, NIH-3T3) animal cell lines. In vivo cytotoxicity was assessed employing the microcrustacean Artemia salina as a model organism, and the internalization of CNDs was observed by fluorescence microscopy.
Abstract The main objective of this master's thesis was to valorize agricultural waste, namely chestnut husks (CNHs), in the sustainable synthesis of carbon nanodots (CNDs), nanoparticles with luminescent and biological properties, with great potential in the biomedical field, especially in medical imaging. The synthesis of CNDs was carried out via hydrothermal carbonization with conventional heating (HCCH) of CNHs. The physical-chemical characterization of CNHs and the synthesis methods used to obtain CNDs will be presented and discussed throughout this dissertation. To establish the optimal synthesis conditions for enhancing the optical and biological properties of CNDs, a 23 factorial design was employed. This analysis revealed that the significant factors in the CNDs synthesis are the nature of the additive, the reaction time, and the additive/CNHs ratio. The structural characterization of the synthesized CNDs was established by Fourier transform infrared spectroscopy (FTIR), proton magnetic resonance (1H NMR), and elemental analysis (EA), and their morphological characterization was evaluated by atomic force microscopy (AFM). The photophysical properties were determined using fundamental state absorption spectroscopy (UV-Vis) and steady-state luminescence. The lifetime and potential of the CNDs were also determined. The biological properties of the CNDs were explored in vitro, including their antioxidant activity, assessed using the ABTS radical method; their anti-inflammatory potential, evaluated through the inhibition of protein denaturation; and their antibacterial activity against Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria, determined by the disc diffusion method. The cytotoxicity of the CNDs was also evaluated in vitro using tumor (S180, HeLa) and non-tumor (VERO, NIH-3T3) animal cell lines. In vivo cytotoxicity was assessed employing the microcrustacean Artemia salina as a model organism, and the internalization of CNDs was observed by fluorescence microscopy.
Descrição
Palavras-chave
Nanopontos de carbono (NPsC) Ouriços da castanha (OsC) Carbonização hidrotérmica Fluorescência Propriedades biológicas Carbon nanodots (CNDs) Chestnut husks (CNHs) Hydrothermal carbonization Fluorescence Biological properties IPL/IDI&CA2024/CN2NDots_ISEL