The common drawbacks of current colorimetric sensors using gold nanoparticle aggregation is its relatively low sensitivity and narrow dynamic range, which restrict their application in real sample analysis when competing with other analytical techniques such as fluorescence and chemiluminescence. In this article, we demonstrate a novel strategy to construct colorimetric sensors based on gold nanoparticle aggregation. Unlike the conventional colorimetric sensors which cause the formation of large nanoparticle aggregates, in our strategy, dimers are selectively formed upon target binding, which results in significantly improved long-term stability and a more than 2 orders of magnitude wider dynamic range of detection than that of the conventional colorimetric sensors. In addition, a strategy to minimize the interparticle gap through the formation of a Y-shaped DNA duplex enables to increase the limit of detection by 10,000 times. The analytical figures of merit of the proposed sensor are comparable to those of the fluorescence-based sensors.

The capability of monitoring the differentiation process in living stem cells is crucial to the understanding of stem cell biology and the practical application of stem-cell-based therapies, yet conventional methods for the analysis of biomarkers related to differentiation require a large number of cells as well as cell lysis. Such requirements lead to the unavoidable loss of cell sources and preclude real-time monitoring of cellular events. In this work, we report the detection of microRNAs (miRNAs) in living human mesenchymal stem cells (hMSCs) by using polydopamine-coated gold nanoparticles (Au@PDA NPs). The PDA shell facilitates the immobilization of fluorescently labeled hairpin DNA strands (hpDNAs) that can recognize specific miRNA targets. The gold core and PDA shell quench the fluorescence of the immobilized hpDNAs, and subsequent binding of the hpDNAs to the target miRNAs leads to their dissociation from Au@PDA NPs and the recovery of fluorescence signals. Remarkably, these Au@PDA-hpDNA nanoprobes can naturally enter stem cells, which are known for their poor transfection efficiency, without the aid of transfection agents. Upon cellular uptake of these nanoprobes, we observe intense and time-dependent fluorescence responses from two important osteogenic marker miRNAs, namely, miR-29b and miR-31, only in hMSCs undergoing osteogenic differentiation and living primary osteoblasts but not in undifferentiated hMSCs and 3T3 fibroblasts. Strikingly, our nanoprobes can afford long-term tracking of miRNAs (5 days) in the differentiating hMSCs without the need of continuously replenishing cell culture medium with fresh nanoprobes. Our results demonstrate the capability of our Au@PDA-hpDNA nanoprobes for monitoring the differentiation status of hMSCs (i.e., differentiating versus undifferentiated) via the detection of specific miRNAs in living stem cells. Our nanoprobes show great promise in the investigation of the long-term dynamics of stem cell differentiation, identification and isolation of specific cell types, and high-throughput drug screening.

The overall response rate for anti-PD-1 therapy remains modest in hepatocellular carcinoma (HCC). We found that a combination of interferon alpha (IFN-a) and anti-PD-1-based immunotherapy resulted in enhanced antitumor activity in unresectable HCC patients. In both immunocompetent orthotopic and spontaneous HCC models, IFN-a therapy synergized with anti-PD-1 and the combination treatment led to significant enrichment of cytotoxic CD27+ CD8+ T cells. Mechanistically, IFN-a suppressed HIF1a signaling by inhibiting FosB transcription in HCC cells, resulting in reduced glucose consumption capacity and consequentially establishing the high-glucose microenvironment that fostered transcription of the T cell costimulatory molecule Cd27 via mTOR-FOXM1 signaling in infiltrating CD8+ T cells. Together, these data reveal that IFN-a reprograms glucose metabolism within HCC tumor microenvironment, thereby liberating T cell cytotoxic capacities and potentiating the PD-1 blockade-induced immune response. Our findings suggest that IFN-a and anti-PD-1 cotreatment is an effective novel combination strategy for HCC patients.

Mussel adhesion has inspired the development of catechol-based adhesive polymers. However, conventional strategies require basic pH conditions and lead to the loss of adhesion. To solve the problem, we report the first attempt to use thiourea-functionalized polymers for preserving hydrogel adhesion. We believe that this simple thiourea-quinone coupling chemistry is instrumental to synthetic adhesive materials.

Substrate stiffness has been shown to regulate the differentiation fate of human mesenchymal stem cells (hMSCs). hMSCs sense and respond to substrate rigidity by exerting traction forces upon the binding between integrins and integrin-specific ligands present on the substrate surface. However, in previous studies, integrin-specific ligands such as Arg-Gly-Asp (RGD) peptides are always grafted to the substrate by a permanent covalent bond. Whether the coupling strength of integrin-specific ligands on substrate will influence cell behaviors has not been explored. In this work, we have developed a facile platform to investigate the effects of varied coupling strength between the RGD peptide and the glass substrate on stem cell behaviors. Glass coverslips are decorated with positive charges by silanization using (3-aminopropyl) triethoxysilane (APTES) to immobilize negatively charged citrate-capped gold nanoparticles (cit-AuNPs) solely via electrostatic interactions. The monolayer of electrostatically immobilized cit-AuNPs is further conjugated with the thiolated RGD peptides through the sulfur-gold bond. The substrate coupling strength of the RGD peptides, which is dependent on the electrostatic interactions between the APTES-treated glass substrate and the cit-AuNPs, is simply tuned by changing the APTES dosage and, hence, the resultant positive charge density on the surface. A total of 0.5% and 12.5% of APTES are used to fabricate low-coupling-strength surfaces (namely, LCS0.5 and LCS12.5), whereas 25% and 50% of APTES are used to fabricate high-coupling-strength surfaces (namely, HCS25 and HCS50). Fluorescence microscopy shows that hMSCs spread well and form stable actin filamentous structure on HCS surfaces but not on LCS surfaces. Remarkably, hMSCs exhibit enhanced osteogenesis on HCS surfaces as revealed by the immunostaining results of multiple early osteogenic markers. These differential behaviors may be governed by Yes-associated protein (YAP), a mechanosensitive transcriptional regulator of stem cells. Our findings highlight the importance of the substrate coupling strength of integrin-binding ligands on regulating adhesion, spreading, and differentiation of hMSCs.

A method, quantitative analysis of multicomponents by single marker (QAMS), was established in this article to investigate the quality control of a traditional Chinese medicine, Oviductus Ranae. 7-Hydroxycholesterol, 7-ketocholesterol, 4-cholesten-3-one, stigmasterol, 7-dehydrocholesterol, and cholesterol were selected as the indexes of quality evaluation of Oviductus Rana. The determination was achieved on an Agilent HC-C18 column (4.6 mm × 250 mm, 5 μm) using methanol with water (87 : 13 v/v) as mobile phase at the flow rate of 2.0 mL/min. Cholesterol was used as an internal standard to determine the relative correction factors between cholesterol and other steroidal constituents in Oviductus Ranae. The contents of those steroidal constituents were calculated at the same time. To evaluate the QAMS method, an external standard method was used to determine the contents of six steroidal constituents. No significant difference was observed when comparing the quantitative results of QAMS with the results of external standard method. The proposed QAMS method was proved to be accurate and feasible based on methodological experiments. QAMS provided a simple, efficient, economical, and accurate way to control the quality of Oviductus Ranae.

While spatial proteomics by fluorescence imaging has quickly become an essential discovery tool for researchers, fast and scalable methods to classify and embed single-cell protein distributions in such images are lacking. Here, we present the design and analysis of the results from the competition Human Protein Atlas – Single-Cell Classification hosted on the Kaggle platform. This represents a crowd-sourced competition to develop machine learning models trained on limited annotations to label single-cell protein patterns in fluorescent images. The particular challenges of this competition include class imbalance, weak labels and multi-label classification, prompting competitors to apply a wide range of approaches in their solutions. The winning models serve as the first subcellular omics tools that can annotate single-cell locations, extract single-cell features and capture cellular dynamics.

Gold nanoparticles (AuNPs), with elegant thermal, optical, or chemical properties due to quantum size effects, may serve as unique species for therapeutic or diagnostic applications. It is worth mentioning that their small size also results in high surface activity, leading to significantly impaired stability, which greatly hinders their biomedical utilizations. To overcome this problem, various types of macromolecular materials are utilized to anchor AuNPs so as to achieve advanced synergistic effect by dispersing, protecting, and stabilizing the AuNPs in polymeric-Au hybrid self-assemblies. In this review, the most recent development of polymer-AuNP hybrid systems, including AuNPs@polymeric nanoparticles, AuNPs@polymeric micelle, AuNPs@polymeric film, and AuNPs@polymeric hydrogel are discussed with respect to their different synthetic strategies. These sophisticated materials with diverse functions, oriented toward biomedical applications, are further summarized into several active domains in the areas of drug delivery, gene delivery, photothermal therapy, antibacterials, bioimaging, etc. Finally, the possible approaches for future design of multifunctional polymer-AuNP hybrids by combining hybrid chemistry with biological interface science are proposed.