Octahydroindolizine alkaloid Homocrepidine A from Dendrobium crepidatum attenuate P. acnes-induced inflammatory in vitro and in vivo.

ETHNOPHARMACOLOGICAL RELEVANCE: Dendrobium crepidatum Lindl. ex Paxton is a perennial epiphyte of Dendrobium genus, distributed in southern China, and utilized as the traditional Chinese medicine "Shihu" in Yunnan Province. Due to its heat-clearing and detoxicating properties, it is formulated as the "XiaoCuoWan" as recorded in the China Pharmacopoeia, and specially used to treat chronic skin inflammatory diseases, such as acne. AIM OF THE STUDY: This research aimed to estimate impact of the octahydroindoline alkaloid Homocrepidine A (HCA), isolated from D. crepidatum, on acne inflammation using both human THP-1 cells and mouse models. Furthermore, the potential anti-inflammatory mechanism of HCA has been analyzed through molecular biology methods and computer simulation. MATERIALS AND METHODS: THP-1 cells and mouse models induced by live Propionibacterium acnes (P. acnes) were employed to evaluate the anti-inflammatory properties of crude extract of D. crepidatum (DCE) and HCA. ELISA was utilized to detect the release of inflammatory cytokines in both cellular and murine ear tissues. RNAseq was used to screen the pathways associated with HCA-mediated inflammatory inhibition, while Western blot, RT-qPCR, and immunofluorescence were utilized to detect the expression of relevant proteins. Additionally, molecular docking simulations and cellular thermal shift assays were employed to confirm the target of HCA. RESULTS: Our research shows that DCE and HCA can effectively alleviate acne inflammation. HCA inhibits TLR2 expression by interacting with amino acid residues in the TIR domain of hTLR2, including Pro-681, Asn-688, Trp-684, and Ile-685. Moreover, HCA disrupts inflammatory signal transduction mediated by MAPK and NF-κB pathways through MyD88-dependent pathway. Additionally, HCA treatment facilitates Nrf2 nuclear translocation and upregulates HO-1 expression, thereby inhibiting NLRP3 inflammasomes activation. In vivo experiments further revealed that HCA markedly attenuated erythema and swelling caused by P. acnes in mice ears, while also decreasing the expression of pro-inflammatory cytokines IL-1ß and IL-8. CONCLUSIONS: Our research highlights the protective effects of D. crepidatum and its bioactive compound HCA against acne inflammation, marking the first exploration of its potential in this context. The discoveries indicate that HCA treatment may represent a promising functional approach for acne therapy.

Integrated analysis of ferroptosis and stemness based on single-cell and bulk RNA-sequencing data provide insights into the prognosis and treatment of esophageal carcinoma.

BACKGROUND: Cancer stem cells (CSCs) play a significant role in the recurrence and drug resistance of esophageal carcinoma (ESCA). Ferroptosis is a promising anticancer therapeutic strategy that effectively targets CSCs exhibiting high tumorigenicity and treatment resistance. However, there is a lack of research on the combined role of ferroptosis-related genes (FRGs) and stemness signature in the prognosis of ESCA. METHODS: The cellular compositions were characterized using single-cell RNA sequencing (scRNA-seq) data from 18 untreated ESCA samples. 50 ferroptosis-related stemness genes (FRSGs) were identified by integrating FRGs with stemness-related genes (SRGs), and then the cells were grouped by AUCell analysis. Next, functional enrichment, intercellular communication, and trajectory analyses were performed to characterize the different groups of cells. Subsequently, the stem-ferr-index was calculated using machine learning algorithms based on the expression profiles of the identified risk genes. Additionally, therapeutic drugs were predicted by analyzing the GDSC2 database. Finally, the expression and functional roles of the identified marker genes were validated through in vitro experiments. RESULTS: The analysis of scRNA-seq data demonstrates the diversity and cellular heterogeneity of ESCA. Then, we identified 50 FRSGs and classified cells into high or low ferroptosis score stemness cells accordingly. Functional enrichment analysis conducted on the differentially up-regulated genes between these groups revealed predominant enrichment in pathways associated with intercellular communication and cell differentiation. Subsequently, we identified 9 risk genes and developed a prognostic signature, termed stem_ferr_index, based on these identified risk genes. We found that the stem-ferr-index was correlated with the clinical characteristics of patients, and patients with high stem-ferr-index had poor prognosis. Furthermore, we identified four drugs (Navitoclax, Foretinib, Axitinib, and Talazoparib) with potential efficacy targeting patients with a high stem_ferr_index. Additionally, we delineated two marker genes (STMN1 and SLC2A1). Particularly noteworthy, SLC2A1 exhibited elevated expression levels in ESCA tissues and cells. We provided evidence suggesting that SLC2A1 could influence the migration, invasion, and stemness of ESCA cells, and it was associated with sensitivity to Foretinib. CONCLUSION: This study constructed a novel ferroptosis-related stemness signature, identified two marker genes for ESCA, and provided valuable insights for developing more effective therapeutic targets targeting ESCA CSCs in the future.

The effects of parent-child separation on the digital literacy of children and adolescents: A bidirectional perspective study.

From a bidirectional perspective, the present cross-sectional study explored the impacts of parent-child separation on the digital literacy of children and adolescents. Drawing upon data from 1894 students (12-18 years, 49.33 % females) in Nanling county, China, we found that parent-child separation can negatively affect the digital literacy of children and adolescents, but effects differ between children experiencing parental migration or parental divorce. Parental mediation can act as a mediator in this process while children's digital feedback to parents may be considered as an auxiliary promoter. To further promote the digital literacy of children and adolescents experiencing parent-child separation, assigned tasks from adults in which children can practice knowledge and skills related to digital devices and the Internet are recommended.

Optimization of Screening Strategies for COVID-19: Scoping Review.

BACKGROUND: COVID-19 screening is an effective nonpharmaceutical intervention for identifying infected individuals and interrupting viral transmission. However, questions have been raised regarding its effectiveness in controlling the spread of novel variants and its high socioeconomic costs. Therefore, the optimization of COVID-19 screening strategies has attracted great attention. OBJECTIVE: This review aims to summarize the evidence and provide a reference basis for the optimization of screening strategies for the prevention and control of COVID-19. METHODS: We applied a methodological framework for scoping reviews and the PRISMA-ScR (Preferred Reporting Items for Systematic Reviews and Meta-Analyses Extension for Scoping Reviews) checklist. We conducted a scoping review of the present publications on the optimization of COVID-19 screening strategies. We searched the PubMed, Web of Science, and Elsevier ScienceDirect databases for publications up to December 31, 2022. English publications related to screening and testing strategies for COVID-19 were included. A data-charting form, jointly developed by 2 reviewers, was used for data extraction according to the optimization directions of the screening strategies. RESULTS: A total of 2770 unique publications were retrieved from the database search, and 95 abstracts were retained for full-text review. There were 62 studies included in the final review. We summarized the results in 4 major aspects: the screening population (people at various risk conditions such as different regions and occupations; 12/62, 19%), the timing of screening (when the target population is tested before travel or during an outbreak; 12/62, 19%), the frequency of screening (appropriate frequencies for outbreak prevention, outbreak response, or community transmission control; 6/62, 10%), and the screening and detection procedure (the choice of individual or pooled detection and optimization of the pooling approach; 35/62, 56%). CONCLUSIONS: This review reveals gaps in the optimization of COVID-19 screening strategies and suggests that a number of factors such as prevalence, screening accuracy, effective allocation of resources, and feasibility of strategies should be carefully considered in the development of future screening strategies.

Rational design of a near-infrared dual-emission fluorescent probe for ratiometric imaging of glutathione in cells.

Sensors for which the output signal is an intensity change for a single-emission peak are easily disturbed by many factors, such as the stability of the instrument, intensity of the excitation light, and biological background. However, for ratiometric fluorescence sensors, the output signal is a change in the intensity ratio of two or more emission peaks. The fluorescence intensity of these emission peaks is similarly affected by external factors; thus, these sensors have the ability to self-correct, which can greatly improve the accuracy and reliability of the detection results. To accurately image glutathione (GSH) in cells, gold nanoclusters (AuNCs) with intrinsic double emission at wavelengths of 606 nm and 794 nm were synthesized from chloroauric acid. With the emission peak at 606 nm as the recognition signal and the emission peak at 794 nm as the reference signal, a near-infrared dual-emission ratio fluorescence sensing platform was constructed to accurately detect changes in the GSH concentration in cells. In vitro and in vivo analyses showed that the ratiometric fluorescent probe specifically detects GSH and enables ultrasensitive imaging, providing a new platform for the accurate detection of active small molecules.

Enhancing intracellular mRNA precise imaging-guided photothermal therapy with a nucleic acid-based polydopamine nanoprobe.

Despite significant advancements in cancer research, real-time monitoring and effective treatment of cancer through non-invasive techniques remain a challenge. Herein, a novel polydopamine (PDA) nucleic acid nanoprobe has been developed for imaging signal amplification of intracellular mRNA and precise photothermal therapy guidance in cancer cells. The PDA nucleic acid nanoprobe (PDA@DNA) is constructed by assembling an aptamer hairpin (H1) labeled with the Cy5 fluorophore and another nucleic acid recognition hairpin (H2) onto PDA nanoparticles (PDA NPs), which have exceptionally high fluorescence quenching ability and excellent photothermal conversion properties. The nanoprobe could facilitate cellular uptake of DNA molecules and their protection from nuclease degradation. Upon recognition and binding to the intracellular mRNA target, a catalytic hairpin assembly (CHA) reaction occurs. The stem of H1 unfolds upon binding, allowing the exposed H1 to hybridize with H2, forming a flat and sturdy DNA double-stranded structure that detaches from the surface of PDA NPs. At the same time, the target mRNA is displaced and engages in a new cyclic reaction, resulting in the recovery and significant amplification of Cy5 fluorescence. Using thymidine kinase1 (TK1) mRNA as a model mRNA, this nanoprobe enables the analysis of TK1 mRNA with a detection limit of 9.34 pM, which is at least two orders of magnitude lower than that of a non-amplifying imaging nucleic acid probe. Moreover, with its outstanding performance for in vitro detection, this nanoprobe excels in precisely imaging tumor cells. Through live-cell TK1 mRNA imaging, it can accurately distinguish between tumor cells and normal cells. Furthermore, when exposed to 808-nm laser irradiation, the nanoprobe fully harnesses exceptional photothermal conversion properties of PDA NPs. This results in a localized temperature increase within tumor cells, which ultimately triggers apoptosis in these tumor cells. The integration of PDA@DNA presents innovative prospects for tumor diagnosis and image-guided tumor therapy, offering the potential for high-precision diagnosis and treatment of tumors.

Lysosomes Initiating and DNAzyme-Assisted Intracellular Signal Amplification Strategy for Quantification of Alpha-Fetoprotein in a Single Cell.

Cellular trace proteins are critical for maintaining normal cell functions, with their quantitative analysis in individual cells aiding our understanding of the role of cell proteins in biological processes. This study proposes a strategy for the quantitative analysis of alpha-fetoprotein in single cells, utilizing a lysosome microenvironment initiation and a DNAzyme-assisted intracellular signal amplification technique based on electrophoretic separation. A nanoprobe targeting lysosomes was prepared, facilitating the intracellular signal amplification of alpha-fetoprotein. Following intracellular signal amplification, the levels of alpha-fetoprotein (AFP) in 20 HepG2 hepatoma cells and 20 normal HL-7702 hepatocytes were individually evaluated using microchip electrophoresis with laser-induced fluorescence detection (MCE-LIF). Results demonstrated overexpression of alpha-fetoprotein in hepatocellular carcinoma cells. This strategy represents a novel technique for single-cell protein analysis and holds significant potential as a powerful tool for such analyses.

Development and evaluation of a culturally adapted digital-platform integrated multifaceted intervention to promote the utilization of maternal healthcare services: a single-arm pilot study.

BACKGROUND: The utilization of hospital delivery and antenatal care (ANC) is essential for improving maternal and newborn outcomes. However, social and cultural barriers in underdeveloped rural areas hindered maternal care utilization. This study aims to design and evaluate the effectiveness of a culturally adapted digital-platform intervention to promote maternal care utilization among women in ethnic minority communities in China. METHODS: From January 1st, 2020, to December 31st, 2021, all pregnant women in Mianshan town, Liangshan Autonomous Prefecture, were invited to participate in the intervention. The multifaceted intervention included participatory and cultural-tailored health education on a popular social media platform, transportation subsidies, and capacity building and economic incentives for healthcare providers. The effectiveness of the intervention was evaluated by comparing two groups: mothers who gave live birth before the intervention (January 1st to December 31st, 2019) and mothers whose entire pregnancy period was covered by the intervention. The primary outcomes were the rate of hospital delivery and ANC utilization. Data on pregnant women were retrospectively collected through telephone surveys and the maternal and newborn's health monitoring system. RESULTS: A total of 237 intervention sample and 138 pre-intervention sample were included. The intervention group demonstrated significantly higher rates of hospital delivery (97.5% vs. 87.7%, p < 0.001), timely initiation of ANC (73.0% vs. 62.3%, p = 0.031), and timely completion of five-time ANC visits (37.1% vs.4.3%, p < 0.001) compared to the pre-intervention group. The intervention group was more likely to utilize hospital delivery (OR = 9.26, 95%CI [2.83-30.24], p < 0.001) and ANC, including timely initiation of ANC (OR = 2.18, 95%CI [1.31-3.62], p = 0.003), completion of five ANC visits (OR = 1.72, 95%CI [1.05-2.83], p = 0.032), and timely completion of five ANC visits (OR = 15.12, 95%CI [6.24-36.64], p < 0.001). CONCLUSIONS: The culturally adapted digital-platform integrated multifaceted intervention effectively promoted the utilization of hospital delivery, timely initiation of ANC, and completion of ANC visits in the Yi ethnic community in China. This study provides valuable insights for future interventions targeting maternal healthcare services in underdeveloped ethnic minority communities worldwide. TRIAL REGISTRATION: Chinese Clinical Trial Registry, ChiCTR2300073219. Registered 4 July 2023 - Retrospectively registered, https://www.chictr.org.cn/showproj.html?proj=199202 .

Fabrication of Ag-CaCO3 Nanocomposites for SERS Detection of Forchlorfenuron.

In this study, Ag-CaCO3 nanocomposites were synthesized using silver nitrate as the precursor solution based on calcium carbonate nanoparticles (CaCO3 NPs). The synthesis involved the reaction of calcium lignosulphonate and sodium bicarbonate. The properties of Ag-CaCO3 nanocomposites were studied by various technologies, including an ultraviolet-visible spectrophotometer, a transmission electron microscope, and a Raman spectrometer. The results showed that Ag-CaCO3 nanocomposites exhibited a maximum UV absorption peak at 430 nm, the surface-enhanced Raman spectroscopy (SERS) activity of Ag-CaCO3 nanocomposites was evaluated using mercaptobenzoic acid (MBA) as the marker molecule, resulting in an enhancement factor of 6.5 × 104. Additionally, Ag-CaCO3 nanocomposites were utilized for the detection of forchlorfenuron. The results demonstrated a linear relationship in the concentration range of 0.01 mg/mL to 2 mg/mL, described by the equation y = 290.02x + 1598.8. The correlation coefficient was calculated to be 0.9772, and the limit of detection (LOD) was determined to be 0.001 mg/mL. These findings highlight the relatively high SERS activity of Ag-CaCO3 nanocomposites, making them suitable for analyzing pesticide residues and detecting toxic and harmful molecules, thereby contributing to environmental protection.

mRNA-activated DNAzyme nanoprobe for tumor cell precise imaging and gene therapy.

A novel Au-nucleic acid nanoprobe, catalyzed by mRNA, has been developed for live cell imaging and precise treatment of tumor cells. This nanoprobe exhibits the remarkable ability to differentiate between tumor cells and normal cells through live cell mRNA imaging, while selectively inducing apoptosis in tumor cells.

A S-substituted Nile Blue-derived bifunctional near-infrared fluorescent probe for in vivo carboxylesterase imaging-guided photodynamic therapy of hepatocellular carcinoma.

The development of theranostic probes that integrate both diagnostic and therapeutic functions still remains an intractable challenge in precise cancer treatment. Herein, a novel bifunctional near-infrared (NIR) fluorescent probe (CEP1) for carboxylesterase (CE) imaging and photodynamic therapy (PDT) of hepatocellular carcinoma (HCC) has been firstly developed and successfully applied in vitro and in vivo. The probe was constructed by introducing carbamate as both the recognition unit and the fluorescence quenching unit into the fluorophore S-substituted Nile Blue (ENBS) via a self-eliminating spacer with substituted chloride. It can be activated by CE and hydrolyzed into fluorescent ENBS, which recover fluorescence at about 700 nm, and can generate superoxide radical anions under NIR irradiation. Additionally, the probe could effectively distinguish tumor cells from normal cells by CE imaging of live cells. Furthermore, it could achieve CE imaging in vivo and significantly inhibits tumor growth by imaging-guided PDT. Therefore, this study offers a promising and attractive platform for activatable imaging-guided PDT of HCC.

Ginger (Zingiber officinale Roscoe) preparations for prophylaxis of postoperative nausea and vomiting: A Bayesian network meta-analysis.

ETHNOPHARMACOLOGICAL RELEVANCE: Ginger has been proposed for prevention of postoperative nausea and vomiting (PONV), however it remains equivocal whether ginger can be an alternative option and which certain preparation is optimal for PONV prophylaxis. AIM OF THE STUDY: We conducted a network meta-analysis (NMA) to compare and rank relative efficacy for PONV control among all available ginger preparations collected in the databases. METHODS: Eligible records were identified by retrieving Medline (via Pubmed), Embase, Web of Science, CENTRAL, CNKI, WHO ICTRP and ClinicalTrials.gov for randomized controlled trials that investigated the efficacy of ginger therapies for the prophylaxis of PONV. A bayesian NMA within random-effects models was implemented. Certainty of evidence for estimates was investigated following GRADE framework. We prospectively registered the protocol (CRD 42021246073) in PROSPERO. RESULTS: Eighteen publications comprising 2199 participants with PONV were identified. Ginger oil (RR [95%CI], 0.39 [0.16, 0.96]) appeared to have the highest probability of being ranked best to decrease the incidence of postoperative vomiting (POV), with statistical significance compared with placebo, based on high to moderate confidence in estimates. With regard to reducing postoperative nausea (PON), statistically superiority was not observed in ginger regimens compared with placebo based on moderate to low certainty of evidence. Reduction in antemetic use and nausea intensity were noticed in ginger powder and oil. Ginger was significantly associated with better efficacy for Asian, older age, higher dosage, preoperative administration, hepatobiliary and gastrointestinal surgery. CONCLUSIONS: Ginger oil appeared to be superior to other ginger treatments for the prophylaxis of POV. With regard to reducing PON, ginger preparations indicated no obvious advantages.

Uptake and Enantiomeric Selectivity of ß-Blockers in Lettuce (Lactuca sativa L.) and Tomato (Lycopersicon esculentum M.) in Soil-Pot Culture.

The uptake and translocation of ß-blockers in lettuce (Lactuca sativa L.) and tomato (Lycopersicon esculentum M.) were investigated by carrying out a 70-day soil-pot cultivation. The root uptake parameters of ß-blockers in lettuce decreased in the order of atenolol (ATE) > sotalol (SOT) > propranolol (PRO) with root bioconcentration factors (BCFsroot/soil) of 0.158, 0.136, and 0.096, respectively, which were positively correlated with their water solubility. The BCFroot/soil of ß-blockers in tomato was higher than those in lettuce. ATE and PRO were prone to migrate to the aerial parts of tomato with translocation factors of 3.31 and 4.11, respectively. In tomato fruits, the enantiomeric profile of PRO and ATE shifted to that dominated by the more toxic enantiomer, i.e., (S)-PRO and (R)-ATE. The enantiomeric selectivity of ß-blockers in the edible parts of lettuce and tomato indicated the potential ecotoxicity of these pharmaceuticals for plants and the human exposure risk via vegetable intake.

Stability of SARS-CoV-2 on inanimate surfaces: A review.

The stability of SARS-CoV-2 for varying periods on a wide range of inanimate surfaces has raised concerns about surface transmission; however, there is still no evidence to confirm this route. In the present review, three variables affecting virus stability, namely temperature, relative humidity (RH), and initial virus titer, were considered from different experimental studies. The stability of SARS-CoV-2 on the surfaces of six different contact materials, namely plastic, metal, glass, protective equipment, paper, and fabric, and the factors affecting half-life period was systematically reviewed. The results showed that the half-life of SARS-CoV-2 on different contact materials was generally 2-10 h, up to 5 d, and as short as 30 min at 22 °C, whereas the half-life of SARS-CoV-2 on non-porous surfaces was generally 5-9 h d, up to 3 d, and as short as 4 min at 22 â„ƒ. The half-life on porous surfaces was generally 1-5 h, up to 2 d, and as short as 13 min at 22 °C. Therefore, the half-life period of SARS-CoV-2 on non-porous surfaces is longer than that on porous surfaces, and thehalf-life of the virus decreases with increasing temperature, whereas RH produces a stable negative inhibitory effect only in a specific humidity range. Various disinfection precautions can be implemented in daily life depending on the stability of SARS-CoV-2 on different surfaces to interrupt virus transmission, prevent COVID-19 infections, and avoid over-disinfection. Owing to the more stringent control of conditions in laboratory studies and the lack of evidence of transmission through surfaces in the real world, it is difficult to provide strong evidence for the efficiency of transmission of the contaminant from the surface to the human body. Therefore, we suggest that future research should focus on exploring the systematic study of the entire transmission process of the virus, which will provide a theoretical basis for optimizing global outbreak prevention and control measures.

Apelin/ELABELA-APJ system in cardiac hypertrophy: Regulatory mechanisms and therapeutic potential.

Heart failure is one of the most significant public health problems faced by millions of medical researchers worldwide. And pathological cardiac hypertrophy is considered one of the possible factors of increasing the risk of heart failure. Here, we introduce apelin/ELABELA-APJ system as a novel therapeutic target for cardiac hypertrophy, bringing about new directions in clinical treatment. Apelin has been proven to regulate cardiac hypertrophy through various pathways. And an increasing number of studies on ELABELA, the newly discovered endogenous ligand, suggest it can alleviate cardiac hypertrophy through mechanisms similar or different to apelin. In this review, we elaborate on the role that apelin/ELABELA-APJ system plays in cardiac hypertrophy and the intricate mechanisms that apelin/ELABELA-APJ affect cardiac hypertrophy. We also illuminate and make comparisons of the newly designed peptides and small molecules as agonists and antagonists for APJ, updating the breakthroughs in this field.

A simple and accurate method to quantify real-time contraction of vascular smooth muscle cell in vitro.

Vascular smooth muscle cells (VSMCs) constitute the medial layer of the blood vessel wall. Their contractile state regulates blood flow in physiological and pathological conditions. Current methods for assessing the contractility of VSMCs are not amenable to the high-throughput screening of pharmaceutical compounds. This study aimed to develop a method to address this shortcoming in the field. Real-time contraction was visualized in living VSMCs using the exogenous expression of green fluorescent protein (GFP). Image-Pro Plus software (IPPS) was used to measure various morphological cell indices. In phenylephrine-treated VSMCs, GFP fluorescence imaging was more accurate than brightfield imaging or phalloidin staining in representing VSMC morphology, as measured using IPPS. Among the multiple indices of VSMC shape, area and mean-diameter were more sensitive than length in reflecting the morphological changes in VSMC. We developed a new index, compound length, by combining the mean-diameter and length to differentiate contracted and uncontracted VSMCs. Based on the compound length, we further generated a contraction index to define a single-VSMC contractile status as single-VSMC contraction-index (SVCI). Finally, compound length and SVCI were validated to effectively assess cell contraction in VSMCs challenged with U46619 and KCl. In conclusion, GFP-based indices of compound length and SVCI can accurately quantify the real-time contraction of VSMCs. In future, the new method will be applied to high-throughput drug screening or basic cardiovascular research.

A Novel Fluorescent Aptamer Sensor with DNAzyme Signal Amplification for the Detection of CEA in Blood.

Carcinoembryonic antigen (CEA) is a tumor-specific biomarker; however, its low levels in the early stages of cancer make it difficult to detect. To address the need for analysis of ultra-low-level substances, we designed and synthesized a fluorescent aptamer sensor with DNAzyme signal amplification and used it for the detection of CEA in blood. In the presence of the target protein, the aptamer sequence in the recognition probe binds to the target protein and opens the hairpin structure, hybridizes with the primer and triggers a polymerization reaction in the presence of polymerase to generate double-stranded DNA with two restriction endonuclease Nb.BbvCl cleavage sites. At the same time, the target protein is displaced and continues to bind to another recognition probe, triggering a new round of polymerization reaction, forming a cyclic signal amplification triggered by the target. The experimental results show that the blood detection with CEA has a high sensitivity and a wide detection range. The detection range: 10 fg/mL~10 ng/mL, with a detection limit of 5.2 fg/mL. In addition, the sensor can be used for the analysis of complex biological samples such as blood.

A biodegradable and cofactor self-sufficient aptazyme nanoprobe for amplified imaging of low-abundance protein in living cells.

Despite the progress on the analysis of proteins either in vitro or in vivo, detection and imaging of low-abundance proteins in living cells still remains challenging. Herein, a novel biodegradable and cofactor self-sufficient DNAzyme nanoprobe has been deve-loped for catalytic imaging of protein in living cells with signal amplification capacity. This DNAzyme nanoprobe is constructed by assembling a DNAzyme subunit-containing aptamer hairpin (HP), another DNAzyme subunit strand (DS), and the molecular beacon (MB) substrate strand onto pH-sensitive ZnO@polydopamine nanorods (ZnO@PDA NRs) that work as DNAzyme cofactor suppliers. Such a nanoprobe can facilitate cellular uptake of DNA molecules and protection of them from nuclease degradation as well as release of them in cells by lysosomal acid-triggered dissolution of ZnO@PDA NRs into Zn2+ as DNAzyme cofactor. Upon recognition and binding with the intracellular protein target, the stem of HP is opened, after which the opened HP hybridizes with DS and generates activated DNAzymes. Each activated DNAzyme can catalyze the cleavage of many MB substrates through true enzymatic multiple turnovers, resulting in the separation of the quenched fluorophore/quencher pair labeled in MB and the generation of significantly amplified fluorescence. Using nucleolin (NCL) as a model protein, this nanoprobe enables the analysis of NCL with a detection limit of 1.8 pM, which are at least two orders of magnitude lower than that of non-catalytic imaging probe. Moreover, it could accurately distinguish tumor cells and normal cells by live cell NCL imaging. And the experimental results are also further verified by flow cytometry assays. The developed nanoprobe can be easily extended to detect other biomolecules by the change of their corresponding aptamer sequences, thus providing a promising tool for highly sensitive imaging of low-abundance biomolecules in living cells.

A MnOx-nucleic acid nanoprobe with enzyme-free cascade signal amplification for ultrasensitive intracellular microRNA imaging.

A novel MnOx-nucleic acid nanoprobe was constructed for catalytic imaging of microRNA in living cells based on the combination of catalytic hairpin assembly, hybridization chain reaction, and DNAzyme amplification. This nanoprobe exhibited ultrahigh sensitivity and specificity, and could distinguish tumor cells and normal cells by live cell microRNA imaging.

A colorimetric aptasensor based on a hemin/EpCAM aptamer DNAzyme for sensitive exosome detection.

Exosomes are considered as potential biomarkers that can reflect information from their parent cell-associated cancer microenvironment. Recently, aptasensors have been widely used for cancer and tumor exosome detection. Aptamers related to exosome surface proteins are usually used to introduce a sequence; the aptamer is used for exosome recognition, and the introduced sequence is used to form G-quadruplexes and for signal amplification. In this paper, we found that the EpCAM aptamer is rich in guanine and unimolecular G-quadruplex with a two-layer G-tetrad under acidic conditions, and we investigated its topology, thermal stability and dissociation constant with hemin. Based on this, our proposed colorimetric aptamer sensor combines the unmodified EpCAM aptamer with hemin to construct a hemin/G-quadruplex DNAzyme and catalyze the TMB-H2O2 system to generate a strong colorimetric signal. Therefore, colorimetric signal changes were negatively correlated with the exosome concentration. The linear range of the 1 h assay was 106-108 particles per mL, and the detection limit was 3.94 × 105 particles per mL. In addition, this method can detect exosomes in complex fetal bovine serum samples with good specificity and high sensitivity toward exosomes from breast, liver, and lung cancers with abnormal EpCAM protein expression.