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Pontos de carbono a partir da biomassa de microalgas cultivadas em resíduos alimentares: produção sustentável, bioatividade e aplicação em imagiologia
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Authors
Abstract(s)
O presente trabalho teve como principal objetivo promover a valorização da biomassa da microalga Chlorella vulgaris (BM-Cv) cultivada em meio de cultura suplementado com resíduos alimentares (provenientes do comércio retalhista), através da síntese sustentável de pontos de carbono (PsC) bioativos fluorescentes e posterior avaliação das suas potenciais aplicações, nomeadamente em imagiologia. Os PsC foram sintetizados a partir da BM-Cv por carbonização hidrotérmica através de aquecimento convencional e assistida por radiação micro-ondas, sendo posteriormente submetidos a etapas de isolamento e purificação, através de filtração e extração líquido-líquido. Os nanomateriais de carbono obtidos foram caracterizados estruturalmente por espetroscopia de infravermelho com transformada de Fourier (FTIR), ressonância magnética nuclear de protão (RMN 1H) e análise elementar, enquanto a sua caracterização morfológica preliminar foi realizada por Microscopia de Força Atómica (AFM). As propriedades fotofísicas dos novos PsC foram estudadas através de espetroscopia de absorção no estado fundamental (UV-Vis) e espetroscopia de fluorescência no estado estacionário. A bioatividade dos PsC foi avaliada no que diz respeito à sua atividade antimicrobiana contra duas espécies bacterianas, Escherichia coli e de Staphylococcus aureus, bem como quanto à sua atividade antioxidante. A citotoxicidade dos PsC in vitro foi estudada em linhas celulares animais normais (NIH-3T3 e VERO) e tumorais (S180) e in vivo utilizando o microcrustáceo Artemia salina como organismo modelo. Paralelamente, recorreu-se à técnica de microscopia de fluorescência para analisar a interação dos nanomateriais sintetizados com as linhas celulares em estudo e com o microcrustáceo. A análise das propriedades biológicas permitiu concluir que os PsC exibiram baixa atividade antibacteriana e antioxidante. No entanto, não apresentaram efeitos citotóxicos contra células animais, assim como em organismos vivos. Verificou-se ainda a internalização destas nanopartículas nas linhas celulares animais e em A. salina, evidenciando o seu potencial para marcação celular por fluorescência e consequente aplicação em imagiologia.
Abstract The main goal of this work is to promote the valorization of the biomass of the microalga Chlorella vulgaris (BM-Cv) cultivated in a culture medium supplemented with food waste (from retail trade), through the sustainable synthesis of fluorescent bioactive carbon dots (CDs) and subsequent evaluation of their potential applications, namely in imaging. The CDs were synthesized from BM-Cv via hydrothermal carbonization using conventional heating and microwave-assisted irradiation, followed by isolation and purification steps through filtration and liquid-liquid extraction. The obtained CDs were structurally characterized by Fourier-transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance (NMR 1H) and elemental analysis, while their preliminary morphological characterization was performed using Atomic Force Microscopy (AFM). The photophysical properties of the CDs were studied using fundamental state absorption spectroscopy ((UV-Vis) and steady-state fluorescence spectroscopy. The bioactivity of the CDs was evaluated for their antimicrobial activity against two bacterial species, Escherichia coli and of Staphylococcus aureus, as well as for their antioxidant activity. The in vitro cytotoxicity of the CDs was studied using normal (NIH-3T3 and VERO) and tumoral (S180) animal cell lines and in vivo using the microcrustacean Artemia salina as a model organism. Simultaneously, fluorescence microscopy was employed to analyse the interaction of the nanomaterials with the studied cell lines and the microcrustacean. The analysis of the biological properties of the CDs revealed low antibacterial and antioxidant activity. However, they did not show cytotoxic effects against animal cells or living organisms. Additionally, the internalization of these nanoparticles in animal cell lines and A. salina was observed, highlighting their potential for fluorescence-based cell labelling and imaging applications.
Abstract The main goal of this work is to promote the valorization of the biomass of the microalga Chlorella vulgaris (BM-Cv) cultivated in a culture medium supplemented with food waste (from retail trade), through the sustainable synthesis of fluorescent bioactive carbon dots (CDs) and subsequent evaluation of their potential applications, namely in imaging. The CDs were synthesized from BM-Cv via hydrothermal carbonization using conventional heating and microwave-assisted irradiation, followed by isolation and purification steps through filtration and liquid-liquid extraction. The obtained CDs were structurally characterized by Fourier-transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance (NMR 1H) and elemental analysis, while their preliminary morphological characterization was performed using Atomic Force Microscopy (AFM). The photophysical properties of the CDs were studied using fundamental state absorption spectroscopy ((UV-Vis) and steady-state fluorescence spectroscopy. The bioactivity of the CDs was evaluated for their antimicrobial activity against two bacterial species, Escherichia coli and of Staphylococcus aureus, as well as for their antioxidant activity. The in vitro cytotoxicity of the CDs was studied using normal (NIH-3T3 and VERO) and tumoral (S180) animal cell lines and in vivo using the microcrustacean Artemia salina as a model organism. Simultaneously, fluorescence microscopy was employed to analyse the interaction of the nanomaterials with the studied cell lines and the microcrustacean. The analysis of the biological properties of the CDs revealed low antibacterial and antioxidant activity. However, they did not show cytotoxic effects against animal cells or living organisms. Additionally, the internalization of these nanoparticles in animal cell lines and A. salina was observed, highlighting their potential for fluorescence-based cell labelling and imaging applications.
Description
Dissertação para obtenção do grau de Mestre em Engenharia Biomédica
Keywords
Atividade biológica Carbonização hidrotérmica Fluorescência Microalgas Pontos de carbono Biological activity Carbon nanodots Fluorescence Hydrothermal carbonization Microalgae
Citation
CONDUTO, Mariana Garrido – Pontos de carbono a partir da biomassa de microalgas cultivadas em resíduos alimentares: produção sustentável, bioatividade e aplicação em imagiologia. Lisboa: Instituto Superior de Engenharia de Lisboa. 2024. Dissertação de Mestrado.