Recent Advancements in Nanoparticle-Based Optical Biosensors for Circulating Cancer Biomarkers

The effectiveness of cancer treatment strongly depends on the early detection of the disease. Currently, the most common diagnostic method, tissue biopsy, takes time and can be damaging to the patient. Circulating cancer biomarkers such as circulating tumor DNA, micro-RNA (miRNA), tumor proteins, exosomes, and circulating tumor cells have repeatedly demonstrated their viability as targets for minimally invasive cancer detection through liquid biopsies. However, among other things, achieving a great sensitivity of detection is still challenging due to the very low concentration of biomarkers in fluid samples. This review will discuss how the recent advances in nanoparticle-based biosensors are overcoming these practical difficulties. This report will be focusing mainly on optical transduction mechanisms of metal nanoparticles (M-NPs), quantum dots (QDs), and upconversion nanoparticles (UCNPs).

Detection of Circulating Tumor-Related Materials by Aptamer Capturing and Endogenous Enzyme-Signal Amplification

Circulating tumor-related materials (CTRMs) shed from original or metastatic tumors, carry a lot of tumor information and are considered as important markers for cancer diagnosis and metastasis prognosis. Herein, we report a colorimetric detection strategy for CTRMs based on aptamer-based magnetic isolation and endogenous alkaline phosphatase (AP)-signal amplification. This strategy exhibited high sensitivity and selectivity toward the CTRMs that express AP heterodimers (the target of aptamer, a potential tumor marker). For clinical samples, this CTRM assay significantly discriminated colorectal cancer patients (n = 50) from healthy individuals (n = 39, p < 0.0001). The receiver operating characteristic (ROC) analysis indicated the sensitivity and specificity reached 92% and 82%, respectively, at the optimal cutoff point, the area under the curve of ROC reached 0.93, suggesting great potential for colorectal cancer diagnosis and therapeutic monitoring. Compared with CTC assays, this strategy is simple and has the potential for point-of-care testing.