Inspired by the anti‐freezing mechanisms found in nature, ionic compounds (ZnCl2/CaCl2) are integrated into cellulose hydrogel networks to enhance the freezing resistance. In this work, cotton cellulose is dissolved by a specially designed ZnCl2/CaCl2 system, which endows the cellulose hydrogels specific properties such as excellent freeze‐tolerance, good ion conductivity, and superior thermal reversibility. Interestingly, the rate of cellulose coagulation could be promoted by the addition of extra water or glycerol. This new type of cellulose‐based hydrogel may be suitable for the construction of flexible devices used at temperature as low as −70 °C.

Homogenous electrochemical biosensing strategies have attracted substantial attention, because of their advantages of being immobilization-free and having rapid response and improved recognition efficiency, compared to heterogeneous biosensors; however, the high cost of labeling and the strict reaction conditions of tool enzymes associated with current homogeneous electrochemical methods limit their potential applications. To address these issues, herein we reported, for the first time, a simple label-free and enzyme-free homogeneous electrochemical strategy based on hybridization chain reaction (HCR) for sensitive and highly specific detection of microRNA (miRNA). The target miRNA triggers the HCR of two species of metastable DNA hairpin probes, resulting in the formation of multiple G-quadruplex-incorporated long duplex DNA chains. Thus, with the electrochemical indicator Methylene Blue (MB) selectively intercalated into the duplex DNA chain and the multiple G-quadruplexes, a significant electrochemical signal drop is observed, which is dependent on the concentration of the target miRNA. Thus, using this "signal-off" mode, a simple, label-free and enzyme-free homogeneous electrochemical strategy for sensitive miRNA assay is readily realized. This strategy also exhibits excellent selectivity to distinguish even single-base mismatched miRNA. Furthermore, this method also exhibits additional advantages of simplicity and low cost, since both expensive labeling and sophisticated probe immobilization processes are avoided. Therefore, the as-proposed label-free and enzyme-free homogeneous electrochemical strategy may become an alternative method for simple, sensitive, and selective miRNA detection, and it has great potential to be applied in miRNA-related clinical diagnostics and biochemical research.

For many medical treatments, particularly cancer, it is necessary to develop a biocompatible microscale device that can carry a sufficient amount of a drug and deliver it to target sites. While chemically powered micromotors have been applied in live animal therapy, many of them are difficult to biodegrade in vivo, which might cause toxicity and side effects. Here, we report on a microdevice that consists of a poly­(aspartic acid) (PASP) microtube, a thin Fe intermediate layer, and a core of Zn. This device can be propelled using gastric acid as a fuel. After adsorption of doxorubicin onto a PASP surface, the microrocket can carry drugs, magnetically locate targets, permeate the gastric mucus gel layer, and increase drug retention in the stomach without inducing an obvious toxic reaction. All materials in the microrockets are biocompatible and biodegradable and can be readily decomposed by the gastric acid or by proteases in the digestive tract. Such microrockets, made with poly­(amino acid)­s, will extend the practical biomedical applications of micro- and nanomotors.

As an important biomarker for early cancer diagnostics and a valuable therapeutic target, telomerase has attracted extensive attention concerning its detection and monitoring. Herein, a homogeneous electrochemical strategy based on T7 exonuclease-aided target recycling amplification is proposed for a simple, rapid, and highly sensitive assay of human telomerase activity from crude cancer cell extracts. In this strategy, a 5' methylene blue (MB)-labeled hairpin (HP) probe is designed, which can hybridize with the telomerase reaction products to initiate the subsequent digestion by T7 exonuclease, and a large amount of MB-labeled mononucleotides are released to result in the significantly amplified electrochemical signal. By taking advantage of the high amplification efficiency of T7-aided target recycling, the present assay enables the detection of telomerase activity at the single-cell level, which is superior or comparable to that of the reported literature. Furthermore, the assay was carried out in a homogeneous solution without complex modification or immobilization procedures, which has the merits of simplicity, rapid response, and improved recognition efficiency compared with heterogeneous biosensors. With the ability of fast detection, outstanding sensitivity, and excellent selectivity, this strategy offers a convenient and specific method for telomerase activity detection, which exhibits great potential in the practical application in telomerase-based early stage cancer diagnosis.

BackgroundHepatocellular carcinoma (HCC) is the one of the most common cancers and lethal diseases in the world. DNA methylation alteration is frequently observed in HCC and may play important roles in carcinogenesis and diagnosis.MethodsUsing the TCGA HCC dataset, we classified HCC patients into different methylation subtypes, identified differentially methylated and expressed genes, and analyzed cis- and trans-regulation of DNA methylation and gene expression. To find potential diagnostic biomarkers for HCC, we screened HCC-specific CpGs by comparing the methylation profiles of 375 samples from HCC patients, 50 normal liver samples, 184 normal blood samples, and 3780 samples from patients with other cancers. A logistic regression model was constructed to distinguish HCC patients from normal controls. Model performance was evaluated using three independent datasets (including 327 HCC samples and 122 normal samples) and ten newly collected biopsies.ResultsWe identified a group of patients with a CpG island methylator phenotype (CIMP) and found that the overall survival of CIMP patients was poorer than that of non-CIMP patients. Our analyses showed that the cis-regulation of DNA methylation and gene expression was dominated by the negative correlation, while the trans-regulation was more complex. More importantly, we identified six HCC-specific hypermethylated sites as potential diagnostic biomarkers. The combination of six sites achieved ~ 92% sensitivity in predicting HCC, ~ 98% specificity in excluding normal livers, and ~ 98% specificity in excluding other cancers. Compared with previously published methylation markers, our markers are the only ones that can distinguish HCC from other cancers.ConclusionsOverall, our study systematically describes the DNA methylation characteristics of HCC and provides promising biomarkers for the diagnosis of HCC.Electronic supplementary materialThe online version of this article (10.1186/s13073-018-0548-z) contains supplementary material, which is available to authorized users.