Through rational design of a functional molecular probe with high sequence specificity that takes advantage of sensitive isothermal amplification with simple operation, we developed a one-pot hairpin-mediated quadratic enzymatic amplification strategy for microRNA (miRNA) detection. Our method exhibits ultrahigh sensitivity toward miR-21 with detection limits of 10 fM at 37 °C and 1 aM at 4 °C, which corresponds to nine strands of miR-21 in a 15 μL sample, and it is capable of distinguishing among miRNA family members. More importantly, the proposed approach is also sensitive and selective when applied to crude extractions from MCF-7 and PC3 cell lines and even patient tissues from intraductal carcinoma and invasive ductal carcinoma of the breast.

Pancreatic β cell dysfunction and reduction due to glucose toxicity play a crucial role in the development of type 2 diabetes mellitus (T2DM). Irisin, a novel exercise-induced myokine, reduces obesity, improves insulin resistance and lowers blood glucose by promoting the browning of white adipose tissue, thereby enhancing thermogenesis and increasing energy expenditure. Recent studies have reported that irisin promotes cell proliferation and protects cells from apoptosis. However, the effects of irisin on pancreatic β cells are unknown. Thus, the aim of this study was to investigate the effects and the potential underlying mechanisms of irisin on pancreatic β cell proliferation and apoptosis induced by high glucose. Both in vitro (INS-1 cells) and in vivo (a T2DM rat model) experiments were conducted. Irisin significantly increased the proliferation of INS-1 cells, with the most significant effect observed at 24 h with 100 ng/ml irisin. Irisin also promoted INS-1 cell proliferation via the ERK and p38 MAPK signaling pathways, protected the cells from high-glucose-induced apoptosis by regulating the expression of caspases, Bad, Bax, Bcl-2 and Bcl-xl, and improved pancreatic β cell function. Irisin significantly reduced the body weight and blood glucose values and increased the serum insulin levels of the diabetic rats. An oral glucose tolerance test (OGTT) indicated that irisin also improved the glucose tolerance of T2DM rats. Together, these findings suggest that irisin may have applications in the prevention and treatment of T2DM because of its protective effect on the secretion of pancreatic β cells.

The recently developed DNA-gold nanoparticle (DNA-GNP) biobarcode assay provides polymerase chain reaction (PCR)-like sensitivity for nucleic acid and protein targets without a need for enzymatic amplification. However, application of the conventional assay is challenged by its complex, expensive, time-consuming, and labor-intense procedure. Herein, we present a new electrochemiluminescence (ECL) biobarcode method based on cysteamine-GNP conjugates. In this strategy, an ECL nanoprobe is fabricated that relies on GNP that is modified with tris-(2,2'-bipyridyl) ruthenium (TBR) labeled cysteamine to boost ECL signals and single strand DNA for target recognition. Specifically, a sandwich complex that consists of a biotin labeled capture probe, target DNA, and cysteamine-GNP conjugate is captured by magnetic microparticles (MMPs) and subsequently identified by the ECL signals from loaded TBR. With the use of the developed probe, a limit of detection as low as 100 fM can be achieved and the assay exhibits excellent selectivity for single-mismatched DNA detection even in human serum. The proposed ECL based method should have wide applications in diagnosis of genetic diseases due to its high sensitivity, simplicity, and low cost.

Developing simple and inexpensive methods to ultrasensitively detect biomarkers is important for medical diagnosis, food analysis and environmental security. In recent years, isothermal amplifications with sensitivity, high speed, specificity, accuracy, and automation have been designed based on interdisciplinary approaches among chemistry, biology, and materials science. In this article, we summarize the advances in nanostructure assisted isothermal amplification in the past two decades for the detection of commercial biomarkers, or biomarkers extracted from cultured cells or patient samples. This article has been divided into three parts according to the ratio of target-to-signal probe in the detection strategy, namely, the N : N amplification ratio, the 1 : N amplification ratio, and the 1 : N(2) amplification ratio.

Telomerase is a widely used tumor biomarker for early cancer diagnosis. On the basis of the combined use of aggregation-induced emission (AIE) fluorogens and quencher, a quencher group induced high specificity strategy for detection of telomerase activity from cell extracts and cancer patients' urine specimens was creatively developed. In the absence of telomerase, fluorescence background is extremely low due to the short distance between quencher and AIE dye. In the addition of telomerase, fluorescence enhances significantly. The telomerase activity in the E-J, MCF-7, and HeLa extracts equivalent to 5-10 000 cells can be detected by this method in ∼1 h. Furthermore, the distinguishing of telomerase extracted from 38 cancer and 15 normal urine specimens confirms the reliability and practicality of this protocol. In contrast to our previous results (Anal. Chem. 2015, 87, 6822-6827), these advanced experiments obtain more remarkable specificity.