Protein–quantum dot nanohybrids for bioanalytical applications

Abstract

Quantum dots (QDs) coupled with biomolecules play an important role as optically and chemically stable bioimaging agents for various applications. These inorganic-biological hybrid conjugates have been demonstrated as powerful fluorescence tools for sensing, diagnostics, and labeling. This review focuses on protein-QD nanohybrids for different types of bioanalytical applications. There are various strategies to modify the surface properties of QDs to produce protein-QD nanohybrids that are stable in biological fluids. We expect that multifunctional protein-QD nanohybrids can be used as a powerful optical probe for various biological applications. WIREs Nanomed Nanobiotechnol 2016, 8:178-190. doi: 10.1002/wnan.1345 For further resources related to this article, please visit the WIREs website.

Engineered Repeat Protein Hybrids: The New Horizon for Biologic Medicines and Diagnostic Tools

“…Quantum dots (QDs) are another type of inorganic nanomaterials that have been intensively studied for their use as fluorescent reporters for biomedical applications due to their excellent fluorescence quantum yields, photostability, resistance to photobleaching, and large Stokes shifts. However, traditional chemical synthesis of QDs requires extreme reaction conditions, organic solvents, toxic reagents, and postsynthetic steps that hinder their biological application, and greener protein-based approaches produced QDs with low Φ. , To address this challenge, we recently investigated the design of a metal-coordination site based on four histidines into a CTPR repeat module and generated CTPR scaffolds with different numbers of units for the sustainable synthesis and stabilization of CdS QDs with improved fluorescent properties, photostability, and biocompatibility . These protein–metal QDs hybrids were able to enter into living cells, showing great cell labeling capacity at very low doses, making them useful tools for biomedical applications.…”

B-Cell-Epitope-Based Fluorescent Quantum Dot Biosensors for SARS-CoV-2 Enable Highly Sensitive COVID-19 Antibody Detection

“…Compared with conventional fluorescent dyes (<5 ns), such as SYBR Green, QDs have a high photobleaching resistance (100- to 1000-fold) and a longer excited-state lifetime (10–40 ns) [ 16 ]. QDs can be easily modified by biomolecules, allowing them to be a qualified carrier for various substrates [ 17 , 18 ]. Fluorescent QDs and peptides can match each other’s size on the nanometer scale and have been applied to a variety of biological detections; for example, QDs with cell-penetrating peptides can monitor lysosomal pH fluctuations [ 19 ], QDs with histone-containing peptides can mark E. coli [ 20 ], and QDs with glutathione can detect levodopa concentrations in vivo [ 21 ].…”

Protein Design for the Synthesis and Stabilization of Highly Fluorescent Quantum Dots

“…Nevertheless, these methodologies produce QDs that still display low biocompatibility, sensitivity to pH, and high ionic strength, as well as elevated production costs. − An alternative approach to template and stabilize QDs is to use peptides and proteins with high affinity for transition metals. − In nature, peptides rich in cysteines and glutamic acids, for example, phytochelatins, participate in the packaging and export of toxic cadmium as less harmful cadmium sulfide (CdS) nanocrystals . Taking inspiration from biological strategies, peptide-assisted synthesis of QDs has become a promising method to grow semiconducting nanocrystals − and some examples have been reported on protein–QDs hybrids prepared by the direct synthesis of QDs in aqueous solution. ,,,− Proteins, such as BSA, lysozyme, trypsin, hemoglobin, transferrin, and poly histidine fusion proteins have been used for the synthesis of protein–QDs hybrids. ,,− However, the change of the established organic routes to more sustainable aqueous routes results in significantly decreased fluorescence quantum yields (QY). ,,, Therefore, it is still challenging to produce biocompatible highly fluorescent QDs for biomedical applications.…”