RESUMO
Microalgae starch is receiving increasing attention as a renewable feedstock for biofuel production. Raw microalgae starch from Tetraselmis subcordiformis was proven to be very efficiently hydrolyzed by an α-amylase (AmyP) of glycoside hydrolase subfamily GH13_37 below the temperature of gelatinization (40 °C). The hydrolysis degree reached 74.4 ± 2.2% for 4% raw microalgae starch and 53.2 ± 1.7% for 8% raw microalgae starch after only 2 h. The hydrolysis efficiency was significantly stimulated by calcium ions. The enzyme catalysis of AmyP and its mutants (Q306A and E347A) suggested that calcium ions contributed to the hydrolysis of cyclic structures in raw microalgae starch by a distinctive calcium-binding site Ca2 of AmyP. The study explored raw microalgae starch as a new resource for cold enzymatic hydrolysis and extended our knowledge on the function of calcium in amylolytic enzyme.
Assuntos
Proteínas de Bactérias/química , Clorófitas/química , Microalgas/química , Extratos Vegetais/química , Amido/química , alfa-Amilases/química , Sequência de Aminoácidos , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Biocatálise , Glicosídeo Hidrolases/química , Glicosídeo Hidrolases/genética , Glicosídeo Hidrolases/metabolismo , Hidrólise , Cinética , Dados de Sequência Molecular , Família Multigênica , Extratos Vegetais/metabolismo , Alinhamento de Sequência , Amido/metabolismo , Especificidade por Substrato , Temperatura , alfa-Amilases/genética , alfa-Amilases/metabolismoRESUMO
A reduced graphene oxide (RGO)/gold nanorod (AuNR)/hydroxyapatite (HA) nanocomposite was designed and successfully synthesized for the first time. An anticancer drug, 5-fluorouracil (5FU), was chosen as a model drug to be loaded in RGO/AuNR/HA. The fabricated RGO/AuNR/HA-5FU showed robust, selective targeting and penetrating efficiency against HeLa cells due to the good compatibility and nontoxicity of HA, and showed excellent synergetic antitumor effects through combined chemotherapy (CT) by 5FU and photothermal therapy (PTT) by both RGO and AuNRs under near-infrared (NIR) laser irradiation. More importantly, this synergistic dual therapy based on RGO/AuNR/HA can also minimize side effects in normal cells and exhibits greater antitumor activity because of a multi-stage drug release ability triggered by the pH sensitivity of HA in the first stage and the combined photothermal conversion capabilities of RGO and AuNRs by means of the NIR laser irradiation in the second stage. This study suggests that the novel RGO/AuNR/HA multi-stage drug delivery system may represent a promising potential application of multifunctional composite materials in the biomedical field.
Assuntos
Antimetabólitos Antineoplásicos/uso terapêutico , Fluoruracila/uso terapêutico , Ouro/uso terapêutico , Grafite/uso terapêutico , Nanocompostos/uso terapêutico , Neoplasias/terapia , Antimetabólitos Antineoplásicos/administração & dosagem , Terapia Combinada/métodos , Sistemas de Liberação de Medicamentos/métodos , Durapatita/química , Durapatita/uso terapêutico , Fluoruracila/administração & dosagem , Ouro/química , Grafite/química , Células HeLa , Humanos , Nanocompostos/química , Nanotubos/química , Nanotubos/ultraestrutura , Oxirredução , Óxidos/química , Óxidos/uso terapêutico , Fototerapia/métodosRESUMO
Integration of multimodal treatment strategies combined with localized therapy to enhance antitumor efficacy and reduce side effects is still a challenge. Herein, a novel composite hydrogel containing rGO, amaranth extract (AE) and gold nanoparticles (AuNPs) was prepared by using AE as both reductant and cross-linking agent. The chlorophyll derivatives in AE were also employed as a photodynamic therapy drug. Meanwhile, AuNPs and rGO both have obvious photothermal effects and can accelerate the generation of cytotoxic singlet oxygen (1O2). The temperature increase of rGO/AE/AuNPs precursor is up to 6.3 °C under 808 nm laser irradiation at a power density of 200 mW·cm(-2). The hydrogel shell on in situ tumor cells was easily formed and regulated by near-infrared irradiation within 10 min, which could both retain a high concentration of drugs on the lesion site and prevent them from migrating to normal tissue, thus reducing the side effects. Compared with rGO/AE and AE, rGO/AE/AuNPs showed a remarkably improved and synergistic antitumor effect. The hydrogel possesses good biocompatibility and high hydrophilicity and could be used for loading chemotherapeutics, which provides a new approach for located and multiple antitumor therapies.