Enzyme-linked immunosorbent assay (ELISA) is a technique
designed
for the detection and quantification of (bio)molecules in a liquid
sample. It is a powerful tool in clinical diagnostics, food safety,
and environmental monitoring. However, the main limitation of conventional
ELISA is its low sensitivity, which cannot meet the demand of analyte
analysis in complex (biological) samples. Several successful approaches
capitalizing on the unique physical and chemical properties of nanoparticles
to improve the performance of traditional ELISA have been reported.
In this review, we aim to demonstrate diverse strategies designed
to date that use metal and metal oxide nanoparticles to overcome challenges
associated with ELISA sensitivity and stability. In particular, we
discuss metal and metal oxide nanoparticles as carriers to load enzymes
and antibodies for signal amplification, as enzyme mimics to replace
the natural enzyme label, and as signal transducers to provide fluorescence
or luminescence signals as an alternative output.
This review summarizes novel applications of multifunctional nanozymes in various biomedical-related fields ranging from cancer diagnosis, cancer and antibacterial therapy to regenerative medicine.
Detection of ultralow concentrations of specific nucleic acid sequences is a central challenge in the early diagnosis of genetic diseases and biodefense applications. Herein, we report a simple and homogeneous chemiluminescence (CL) method for ultrasensitive DNA detection. It is based on the exonuclease III (Exo III)-assisted cascade signal amplification and the catalytic effect of G-quadruplex-hemin DNAzyme on the luminol-H2O2 CL system. A quadruplex-forming DNA probe hybridizes a hairpin DNA probe to construct a duplex DNA probe as recognition element. Upon sensing of target DNA, the recognition of target DNA and the duplex DNA probe triggers the Exo III cleavage process, accompanied by releasing target DNA and generating a new secondary target DNA fragment. The released target DNA and the secondary target DNA are recycled. Simultaneously, numerous quadruplex-forming sequences are liberated and bind hemin to yield G-quadruplex-hemin DNAzyme, which subsequently catalyze the luminol-H2O2 reaction to produce strong CL emission. This method exhibited a high sensitivity toward target DNA with a detection limit of 8 fM, which was about 100 times lower than that of the reported DNAzyme-based colorimetric system for DNA detection with Exo III-assisted cascade signal amplification. This method provides a simple, isothermal, and low-cost approach for sensitive detection of DNA and holds a great potential for early diagnosis in gene-related diseases.
Detection of ultralow concentration of specific nucleic acid sequences is important in early diagnosis of gene-related diseases and biodefense application. Herein, we report an amplified chemiluminescence (CL) biosensing platform for ultrasensitive DNA detection. It is based on the exonuclease III-assisted target recycling amplification and catalytic effect of G-quadruplex-hemin DNAzyme to stimulate the generation of CL in the presence of H2O2 and luminol. Moreover, the typical problem of high background induced by excess hemin itself can be effectively addressed through the absorbing of superfluous hemin on the surface of single-walled carbon nanotubes and then removing though centrifugation. Therefore, our proposed biosensing exhibited a high sensitivity toward target DNA with a detection limit of 12 fM, which was about 100-fold lower than that of the DNAzyme-based CL sensor for DNA detection without Exo III-assisted amplification. This sensing platform provides a label-free and cost-effective approach for sensitive detection of DNA.
Artificial enzymes as radical scavengers show great potentials in treatments of various diseases induced by oxidative stress. Herein, the quantitative analysis indicates that the intrinsic activity of nanocerias for the degradation of radicals is determined by the concentration of surface defects as well as their morphological features. The surface Ce fraction of the CeO nanozymes with a similar morphology can be used as a descriptor to index their catalytic activity as radical scavengers. Defect-abundant porous nanorods of ceria (PN-CeO) with a large surface area (141 m/g) and high surface Ce fraction (32.8%) deliver an excellent catalytic capability for the degradation of radicals, which is 15.5 times higher than that of Trolox. Results indicate that PN-CeO not only provides more surface catalytic centers but also supplies the active site with higher activity. Oxidative stress induced by doxorubicin (Dox), an essential medicine for a wide range of tumors, was used as the model system to evaluate the radical degradation ability of PN-CeO. Both in vitro cellar (H9c2 cells) and in vivo animal models revealed that PN-CeO did not affect the cell and rat growth and was able to alleviate the Dox-induced oxidative stress. Results suggest that the artificial PN-CeO nanozymes have potentials to function as an adjuvant medicine during tumor chemotherapy.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.