Investigation of trypsin-CdSe quantum dot interactions via spectroscopic methods and effects on enzymatic activity

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.

Impact of luminescent MoSe2 quantum dots on activity of trypsin under different pH environment

It is vital that a straightforward detection approach for trypsin should be developed as it is important diagnostic tool for a number of diseases. Herein, the impact of luminescent MoSe2 quantum dots on trypsin activity under different pH environment has been studied. Addition of trypsin to MoSe2 quantum dots enhanced the fluorescence of quantum dots whereas quantum dots resulted in quenching of fluorescence of trypsin. The quenching behavior at various pH and temperature was examined and revealed that the MoSe2-trypsin complex stabilized through the electrostatic interactions. The obtained negative values of zeta potential of the complex -0.11 mV, -0.30 mV and -0.59 mV for pH 6.0,7.6 and 9.0 respectively confirmed the stability of the complex. The separation between the donor and acceptor atoms in energy transfer mechanism was found to decrease (1.48 nm to 1.44 nm to 1.30 nm) with increasing value of pH. It was also evident that trypsin retained its enzyme activity in the trypsin-MoSe2 complex and under different pH environment. The Vant Hoff plot from quenching revealed 1 binding site for quantum dots by trypsin for all pH of buffer solution. The complex formation of trypsin-MoSe2 quantum dots was verified for the first time using fluorescence spectroscopy and it revealed that tryspin form complex with MoSe2 quantum dots through electrostatic interactions. Our results revealed that the MoSe2 quantum dots stabilized and sheltered the active sites of trypsin, which was likely the cause of the increased bioavailability of MoSe2 quantum dots in enzymes.

A Comparative Study of Nanobio Interaction of Zn-Doped CdTe Quantum Dots with Lactoferrin Using Different Spectroscopic Methods

In this paper, glutathione (GSH)-coated Zn-doped CdTe quantum dots (QDs) with different particle sizes were synthesized using the "reflow method", and the interaction mechanism between the two QDs and lactoferrin (LF) was investigated systemically with different spectroscopic methods. The steady-state fluorescence spectra showed that the LF formed a tight complex with the two QDs through static bursting and that the electrostatic force was the main driving force between the two LF-QDs systems. The complex generation process was found to be spontaneous (ΔG < 0) and accompanied by exothermic and increasing degrees of freedom (ΔH < 0, ΔS > 0) by using the temperature-dependent fluorescence spectroscopy. The critical transfer distance (R₀) and donor-acceptor distance (r) of the two LF-QDs systems were obtained based on the fluorescence resonance energy transfer theory. In addition, it was observed that the QDs changed the secondary and tertiary structures of LF, leading to an increase in the hydrophobicity of LF. Further, the nano-effect of orange QDs on LF is much larger than that of green QDs. The above results provide a basis for metal-doped QDs with LF in safe nano-bio applications.

Investigation on conformational variation and enzymatic activity of trypsin affected by Ti3C2 QDs via spectroscopic technique and molecular modeling

In this paper, Ti₃C₂ quantum dots (Ti₃C₂ QDs) were synthesized by simply treating Ti₃C₂ MXene powder with acid and base via hydrothermal method. Ti₃C₂ QDs exhibited superior fluorescence property and were used for the fluorescent imaging of living HeLa cells successfully. In order to evaluate the influence of Ti₃C₂ QDs on protease with specific biological functions, binding interaction of Ti₃C₂ QDs with trypsin was studied comprehensively and deeply through spectroscopic strategies and molecular modeling technique. The intrinsic fluorescence of trypsin was spontaneously quenched by Ti₃C₂ QDs through static quenching mode under van der Waals interaction force, and Ti₃C₂ QDs bound with the inactive residue domain of trypsin firmly with stoichiometric ratio of 1:1. Ti₃C₂ QDs induced the microenvironmental variation of the amino acid residues in trypsin, reducing the thermal stability of trypsin significantly. Gel electrophoresis experiments and microscopic imaging experiments demonstrated that Ti₃C₂ QDs inhibited the enzymatic activity of trypsin on the digestion of human serum albumin and HeLa cells obviously. These results revealed not only the deep interaction mechanism between Ti₃C₂ QDs and protease but also the influence of Ti₃C₂ QDs on the enzymatic activity of trypsin, paving the way for the safe biological application of Ti₃C₂ QDs in the diagnosis and the therapy of protease-related diseases.

Influence of zinc doping on the molecular biocompatibility of cadmium-based quantum dots: Insights from the interaction with trypsin

Doping quantum dots (QDs) with extra element presents a promising future for their applications in the fields of environmental monitoring, commercial products and biomedical sciences. However, it remains unknown for the influence of doping on the molecular biocompatibility of QDs and the underlying mechanisms of the interaction between doped-QDs and protein molecules. Using the "one-pot" method, we synthesized N-acetyl-l-cysteine capped CdTe: Zn²⁺ QDs with higher fluorescence quantum yield, improved stability and better molecular biocompatibility compared with undoped CdTe QDs. Using digestive enzyme trypsin (TRY) as the protein model, the interactions of undoped QDs and Zn-doped QDs with TRY as well as the underlying mechanisms were investigated using multi-spectroscopy, isothermal titration calorimetry and dialysis techniques. Van der Waals forces and hydrogen bonds are the major driving forces in the interaction of both QDs with TRY, which leading to the loosening of protein skeleton and tertiary structural changes. Compared with undoped QDs, Zn-doped QDs bind less amount of TRY with a higher affinity and then release higher amount of Cd. Zn-doped QDs have a less stimulating impact on TRY activity by decreasing TRY binding and reducing Cd binding to TRY. Taken all together, Zn-doped QDs offer a safer alternative for the applications of QDs by reducing unwanted interactions with proteins and improving biocompatibility at the molecular level.

Gold nanorods–trypsin biocorona: a novel nano composite for in vitro cytotoxic activity towards MCF-7 and A-549 cancer cells

In the present work, we have synthesized cetyltrimethyl ammonium bromide (CTAB) capped gold nanorods (Au NRs) to evaluate apparent binding affinities for the adsorption of trypsin (TRP).

Interactions of carbon quantum dots from roasted fish with digestive protease and dopamine

The carbon quantum dots from roasted fish interacted with digestive protease and dopamine.

Nonlinear optical properties of metal nanoparticles: a review

Metal nanoparticles (MNPs) hold great technological promise because of the possibility of engineering their electronic and optical properties through material design.

Binding characteristics of psoralen with trypsin: Insights from spectroscopic and molecular modeling studies

Psoralen (PSO) is a naturally occurring furanocoumarin with a variety of pharmacological activities, however very limited information on the interaction of PSO with trypsin is available. In this study, the binding characteristics between PSO and trypsin at physiological pH were investigated using a combination of fluorescence, UV-vis absorption, circular dichroism (CD), Fourier transform infrared (FT-IR) spectroscopic, chemometric and molecular modeling approaches. It was found that the fluorescence quenching of trypsin by PSO was a static quenching procedure, ascribing the formation of a PSO-trypsin complex. The binding of PSO to trypsin was driven mainly by hydrophobic forces as the positive enthalpy change and entropy change values. The molecular docking showed that PSO inserted into the active site pocket of trypsin to interact with the catalytic residues His57, Asp102 and Ser195 and may cause a decrease in trypsin activity. The results of CD and FT-IR spectra along with the temperature-induced denaturation studies indicated that the addition of PSO to trypsin led to the changes in the secondary structure of the enzyme. The concentration profiles and spectra of the three components (PSO, trypsin, and PSO-trypsin complex) obtained by multivariate curve resolution-alternating least squares analysis exhibited the kinetic processes of PSO-trypsin interaction. This study will be helpful to understand the mechanism of PSO that affects the conformation and activity of trypsin in biological processes.

Recent Advances in Synthesis, Properties and Applications of Magnetic Oxide Nanomaterials

Oxide nanomaterials are in great demand due to their unique physical, chemical and structural properties. The nanostructured materials with desired magnetic properties are the future of power electronics. Unique magnetic properties and excellent biocompatibility of these materials found applications in pharmaceutical field also. For these applications, the synthesis of magnetic oxide nanomaterials with required properties is highly desirable. Till now, various techniques have been evolved for the synthesis of oxide nanomaterials with full control over their shape, size, morphology and magnetic properties. In nanoscale, the magnetic properties are totally different from their bulk counterparts. In this range, each nanoparticle acts as a single magnetic domain and shows fast response to applied magnetic field. This review article discusses the synthesis techniques, properties and the applications of magnetic oxide nanomaterials. Various characterization techniques for magnetic materials have been discussed along with the literature of iron oxide, nickel oxide, and cobalt oxide nanomaterials. The challenges for further development of these materials have also been presented to broaden their rapidly emerging applications.