The early diagnosis of cancer is a critical factor in improving patient survival rates, and colorimetric methods have emerged as a promising approach for real-time, naked-eye detection of cancer biomarkers. The rapid development of nanotechnology has enabled the creation of nanomaterials with unique physical and chemical properties, which have been leveraged to enhance the selectivity and sensitivity of colorimetric detection methods.
In recent years, researchers have made significant progress in developing colorimetric nanosensors for cancer diagnosis, achieving remarkable limits of detection (LOD) down to a few cancer cells per milliliter, several femtograms per milliliter of proteins, several nanograms of nucleic acids, or even tens of nanomolars of organic molecules. This review provides an overview of the sensing principles, target biomarkers, advanced nanomaterials, and strategies employed in the fabrication of sensing platforms, highlighting the potential of colorimetric nanosensors to revolutionize cancer diagnosis.
Sensing Principles and Target Biomarkers
Colorimetric nanosensors operate on the principle of detecting changes in the color of a solution in response to the presence of a specific biomarker. This is achieved through the interaction between the biomarker and a nanomaterial, such as gold nanoparticles (AuNPs), platinum-gold nanoparticles (PtAuNPs), or silver nanoprisms, which alters the optical properties of the material. The target biomarkers for cancer diagnosis include proteins, nucleic acids, and small molecules, such as MUC1 proteins, prostate-specific antigen (PSA), prostate cancer antigen gene 3 (PCA3), and glutathione.
Advanced Nanomaterials and Sensing Platforms
The development of advanced nanomaterials has been instrumental in enhancing the performance of colorimetric nanosensors. For example, MUC1 aptamer-conjugated PtAuNPs have been designed to specifically recognize MUC1 proteins on cancer cell surfaces, while the etching of silver nanoprisms has been used to detect PSA. The aggregation or dispersion of AuNPs has also been employed to sense PCA3 or glutathione. These nanomaterials offer improved sensitivity, selectivity, and stability, enabling the detection of cancer biomarkers at extremely low concentrations.
Strategies for Improving Signal Sensitivity and Specificity
Several strategies have been developed to enhance the signal sensitivity and specificity of colorimetric nanosensors. These include the use of amplification techniques, such as rolling circle amplification (RCA) and enzyme-linked aptamer assays (ELAAs), to increase the signal intensity. Additionally, the incorporation of molecular recognition elements, such as aptamers and antibodies, has improved the selectivity of the sensors. The optimization of nanomaterial properties, such as size, shape, and surface chemistry, has also been critical in enhancing the performance of colorimetric nanosensors.
Colorimetric nanosensors have the potential to transform cancer diagnosis, enabling early detection and improving patient outcomes. The development of advanced nanomaterials and sensing platforms has enabled the creation of highly sensitive and specific sensors, capable of detecting cancer biomarkers at extremely low concentrations. As research in this field continues to evolve, it is likely that colorimetric nanosensors will play an increasingly important role in the diagnosis and management of cancer.
