The binding interaction between cadmium-based, aqueous-phase quantum dots with Candida rugosa lipase

Nano-bio convergence unveiled: Systematic review on quantum dots-protein interaction, their implications, and applications

Quantum dots (QDs) are semiconductor nanocrystals (2-10 nm) with unique optical and electronic properties due to quantum confinement effects. They offer high photostability, narrow emission spectra, broad absorption spectrum, and high quantum yields, making them versatile in various applications. Due to their highly reactive surfaces, QDs can conjugate with biomolecules while being used, produced, or unintentionally released into the environment. This systematic review delves into intricate relationship between QDs and proteins, examining their interactions that influence their physicochemical properties, enzymatic activity, ligand binding affinity, and stability. The research utilized electronic databases like PubMed, WOS, and Proquest, along with manual reviews from 2013 to 2023 using relevant keywords, to identify suitable literature. After screening titles and abstracts, only articles meeting inclusion criteria were selected for full text readings. This systematic review of 395 articles identifies 125 articles meeting the inclusion criteria, categorized into five overarching themes, encompassing various mechanisms of QDs and proteins interactions, including adsorption to covalent binding, contingent on physicochemical properties of QDs. Through a meticulous analysis of existing literature, it unravels intricate nature of interaction, significant influence on nanomaterials and biological entities, and potential for synergistic applications harnessing both specific and nonspecific interactions across various fields.

An update on the biological effects of quantum dots: From environmental fate to risk assessment based on multiple biological models

Quantum dots (QDs) are zero-dimension nanomaterials with excellent physical and chemical properties, which have been widely used in environmental science and biomedicine. Therefore, QDs are potential to cause toxicity to the environment and enter organisms through migration and bioenrichment effects. This review aims to provide a comprehensive and systematic analysis on the adverse effects of QDs in different organisms based on recently available data. Following PRISMA guidelines, this study searched PubMed database according to the pre-set keywords, and included 206 studies according to the inclusion and elimination criteria. CiteSpace software was firstly used to analyze the keywords of included literatures, search for breaking points of former studies, and summarize the classification, characterization and dosage of QDs. The environment fate of QDs in the ecosystems were then analyzed, followed with comprehensively summarized toxicity outcomes at individual, system, cell, subcellular and molecular levels. After migration and degradation in the environment, aquatic plants, bacteria, fungi as well as invertebrates and vertebrates have been found to be suffered from toxic effects caused by QDs. Aside from systemic effects, toxicity of intrinsic QDs targeting to specific organs, including respiratory system, cardiovascular system, hepatorenal system, nervous system and immune system were confirmed in multiple animal models. Moreover, QDs could be taken up by cells and disturb the organelles, which resulted in cellular inflammation and cell death, including autophagy, apoptosis, necrosis, pyroptosis and ferroptosis. Recently, several innovative technologies, like organoids have been applied in the risk assessment of QDs to promote the surgical interventions of preventing QDs' toxicity. This review not only aimed at updating the research progress on the biological effects of QDs from environmental fate to risk assessment, but also overcame the limitations of available reviews on basic toxicity of nanomaterials by interdisciplinarity and provided new insights for better applications of QDs.

Size- and surface functionalization-driven molecular interaction of CdSe quantum dots with jack bean urease: multispectroscopic, thermodynamic, and AFM approach

Quantum dots (QDs) with distinctive optical properties have been extensively researched and developed for usage in solar cells, imaging, drug delivery, cellular targeting, etc. But the inevitable production of QDs can lead to their unavoidable release and increased environmental concentration. Depending on morphological and surface properties, QDs at the nano-bio interface considerably impact the activity and structure of bio-molecules. The present study investigates the interaction of metalloenzyme jack bean urease (JBU) and bi-sized CdSe QDs (2.43 nm and 3.63 nm), surface-functionalized to mercaptopropionic acid (MPA) (-COOH), L-cysteine (CYS), L-glutathione (GSH), N-acetyl L-cysteine (NAC) (-COOH, -NH₂), and cysteamine hydrochloride (CYST) (-NH₂) to assess any alterations in JBU's binding, microenvironment, structure, exciton lifetime, and activity. JBU catalyzes the hydrolysis of urea to produce ammonia and carbon dioxide; any changes in its properties could threaten the survival of several microbes and plants. Spectroscopy techniques such as UV-Vis, fluorescence, circular dichroism, synchronous, time-resolved fluorescence, atomic force microscopy, and JBU activity assay were studied. Results suggested highly spontaneous and energy-favored interactions, which involved static quenching and hydrophobic forces of varied magnitude, dependent on QDs properties. The size, surface modifications, and dosage of QDs significantly impacted the secondary structure and activity of JBUs. Even though the larger sizes of the relevant modifications demonstrated stronger binding, the smaller sizes had the greatest impact on α-helicity and activity. CYST-capped QDs with an average number of the binding site (n) = 1, reduced α-helicity by 16% and activity by 22-30% at 7 nM concentration. In contrast, MPA-capped QDs with n < 1 had the least effect on α-helical structure and activity. The smaller GSH-capped QDs increased the activity by 9%, via partially restoring JBU's α-helical content. The study thus thoroughly analyzed the impact of varied-size and surface-functionalized QDs on the structure and function of JBU, which can be exploited further for several biomedical applications.

Toxic mechanism of pyrene to catalase and protective effects of vitamin C: Studies at the molecular and cell levels

Polycyclic aromatic hydrocarbons, distributing extensively in the soil, would potentially threaten the soil organisms (Eisenia fetida) by triggering oxidative stress. As a ubiquitous antioxidant enzyme, catalase can protect organisms from oxidative damage. To reveal the potential impact of polycyclic aromatic hydrocarbon pyrene (Pyr) on catalase (CAT) and the possible protective effect of Ascorbic acid (vitamin C), multi-spectral and molecular docking techniques were used to investigate the influence of structure and function of catalase by pyrene. Fluorescence and circular dichroism analysis showed that pyrene would induce the microenvironmental changes of CAT amino acid residues and increase the α-helix in the secondary structure. Molecular simulation results indicated that the main binding force of pyrene around the active center of CAT is hydrogen bonding force. Furthermore, pyrene inhibited catalase activity to 69.9% compared with the blank group, but the degree of inhibition was significantly weakened after vitamin C added into the research group. Cell level experiments showed that pyrene can increase the level of ROS in the body cavity cell of earthworms, and put the cells under the threat of potential oxidative damage. Antioxidants-vitamin C has a protective effect on catalase and maintains the stability of intracellular ROS levels to a certain extent.

Binding mechanism of maltol with catalase investigated by spectroscopy, molecular docking, and enzyme activity assay

Maltol is a flavor additive that is widely used in the daily diet of humans, and its biosafety attention is concomitantly increasing. Catalase (CAT) is an antioxidant enzyme to maintain homeostasis in the tissue's environment of human body and protect cells from oxidative damages. The adverse effects of maltol to CAT activity within mouse hepatocytes as well as the structural and functional changes of CAT on molecular level were investigated by multiple spectroscopy techniques, enzyme activity experiments, and molecular docking. Results suggested that when the maltol concentrations reached to 8 × 10^-5 mol L^-1 , the viability of hepatocytes decreased to 93%, and CAT activity was stimulated by maltol to 111% than the control group after exposure for 24 hours. Changes in CAT activity on molecular level were consistent with those on cellular level. The fluorescence quenching of CAT by maltol was static with the forming of maltol-CAT complex. Moreover, ultraviolet-visible (UV-visible) absorption, synchronous fluorescence, and circular dichroism (CD) spectra reflected that the presence of maltol caused conformational change of CAT and made the CAT molecule skeleton loose and increased α-helix of CAT. Maltol mainly bound with CAT through hydrogen bond, and binding site that is near the heme ring in the enzyme activity center did not interact with its main amino acid residues. This study explores the combination between maltol and CAT, providing references for evaluating health damages caused by maltol.