Dual-potential ratiometric electrochemiluminescence based on single emitter and single coreactant for the sensitive detection of carcinoembryonic antigen.

Dual-potential ratiometric electrochemiluminescence (ECL) is in favor of resistance to environmental interference. However, two kinds of emitters or coreactants, and a wide scan potential range (>2 V) are mandatory. This work developed a new dual-potential ratiometric ECL sensor for detection of carcinoembryonic antigen (CEA) using single emitter (luminol) and single coreactant (H2O2) with a mild potential range from -0.1 to 0.6 V. Luminol could produce a strong cathodic ECL (Ec) induced by hydroxyl radicals (HO‧) from the reduction of H2O2, and a relatively weak anodic ECL (Ea). After the ferrocene modified CEA aptamer (Apt-Fc) was attached, Fc could promote Ea by catalyzing the oxidation of H2O2, and reduce Ec by consuming HO‧. With the cycling amplification of the exonuclease I, CEA could substantially reduce the amount of Apt-Fc, resulting in the decrease of Ea and the rise of Ec. So, the ratio of Ec to Ea (Ec/Ea) was used as the detection signal, realizing the sensitive determination of CEA from 0.1 pg mL-1 to 10 ng mL-1 with a LOD of 41.85 fg mL-1 (S/N = 3). The developed sensor demonstrated excellent specificity, stability and reproducibility, with satisfactory results in practical detection.

The applications of 3D printing in wound healing: The external delivery of stem cells and antibiosis.

As the global number of chronic wound patients rises, the financial burden and social pressure on patients increase daily. Stem cells have emerged as promising tissue engineering seed cells due to their enriched sources, multidirectional differentiation ability, and high proliferation rate. However, delivering them in vitro for the treatment of skin injury is still challenging. In addition, bacteria from the wound site and the environment can significantly impact wound healing. In the last decade, 3D bioprinting has dramatically enriched cell delivery systems. The produced scaffolds by this technique can be precisely localized within cells and perform antibacterial actions. In this review, we summarized the 3D bioprinting-based external delivery of stem cells and their antibiosis to improve wound healing.

Efficacy and Safety of Tyrosine Kinase Inhibitors Alone or Combination with Programmed Death-1 Inhibitors in Treating of Hepatitis C-Related Hepatocellular Carcinoma.

Background: Tyrosine kinase inhibitors (TKI) combined with programmed cell death-1 (PD-1) inhibitor is a potential treatment modality for patients with HCV-related unresectable hepatocellular carcinoma (uHCC). Methods: The participants of the present work included the patients having HCV-related uHCC who were treated with TKI monotherapy (TKI group) or TKI combined with PD-1 inhibitors therapy (combination group) in our center between June 2018 and June 2021. In addition, the patients were classified into RNA-positive and RNA-negative groups based on whether or not the baseline HCV RNA was detectable. The overall survival (OS) was used as the primary efficacy endpoint, while progression-free survival (PFS), objective response rate (ORR), and disease control rate (DCR) were used as secondary endpoints. The adverse events were recorded and evaluated. Results: Among the 67 patients contained this work, 43 patients were classified into the TKI group, while 24 patients formed the combination group. In relative to the TKI group, the combination group presented notably better median OS (21 months vs 13 months, p = 0.043) and median PFS (8 months vs 5 months, p = 0.005). No evident differences were observed between the two groups in terms of the DCR (58.1% vs 79.2%, p = 0.080), ORR (13.9% vs 25.0%, p = 0.425) and the incidence of grade 3-4 adverse events (34.8% vs 33.3%, p = 1.000). In addition, there existed no obvious difference between the RNA-positive group and RNA-negative group in terms of median OS (14 months vs 19 months, p = 0.578) and median PFS (4 months vs 6 months, p = 0.238). Conclusion: The patients having HCV-related uHCC after being treated with the TKI and PD-1 inhibitor combination therapy exhibited a better prognosis and manageable toxicity compared to the patients who underwent TKI monotherapy.

Real-world efficacy and prognostic factors of lenvatinib plus PD-1 inhibitors in 378 unresectable hepatocellular carcinoma patients.

INTRODUCTION: Combining lenvatinib with a programmed cell death protein-1 (PD-1) inhibitor has been explored for the treatment of un-resectable hepatocellular carcinoma (uHCC). This study aimed to investigate the real-world efficacy of and prognostic factors for survival associated with lenvatinib plus PD-1 inhibitor treatment in a large cohort of Asian uHCC patients even the global LEAP-002 study failed to achieve the primary endpoints. METHODS: Patients with uHCC treated with lenvatinib and PD-1 inhibitors were included. The primary endpoints were overall survival (OS) and progression-free survival (PFS), and the secondary endpoints were the objective response rate (ORR) and adverse events (AEs). Prognostic factors for survival were also analyzed. RESULTS: A total of 378 uHCC patients from two medical centers in China were assessed retrospectively. The median patient age was 55 years, and 86.5% of patients were male. Hepatitis B virus (HBV) infection (89.9%) was the dominant etiology of uHCC. The median OS was 17.8 (95% confidence interval (CI) 14.0-21.6) months. The median PFS was 6.9 (95% CI 6.0-7.9) months. The best ORR and disease control rate (DCR) were 19.6% and 73.5%, respectively. In multivariate analysis, Child‒Pugh grade, Barcelona Clinic Liver Cancer stage, Eastern Cooperative Oncology Group performance status score, involved organs, tumor burden score, and combination with local therapy were independent prognostic factors for OS. A total of 100% and 57.9% of patients experienced all-grade and grade 3/4 treatment-emergent AEs, respectively. CONCLUSION: This real-world study of lenvatinib plus PD-1 inhibitor treatment demonstrated long survival and considerable ORRs and DCRs in uHCC patients in China. The tolerability of combination therapy was acceptable but must be monitored closely.

A multi-center retrospective study on the efficacy and safety of regorafenib vs. regorafenib combined with PD-1 inhibitors as a second-line therapy in patients with advanced hepatocellular carcinoma.

Background: At present, there are no definitive optimal treatment options for patients with hepatocellular carcinoma (HCC) following first-line treatment failure. To maximize the survival benefit of patients, we compared the combination therapy of regorafenib and programmed death-1 (PD-1) inhibitors with regorafenib monotherapy as a second-line treatment for patients with advanced HCC. Methods: Our multicenter retrospective study evaluated consecutive patients with advanced HCC who received regorafenib plus PD-1 inhibitors or regorafenib alone as a later-line therapy from May 2019 to January 2022. The primary endpoint was progression-free survival (PFS), and the secondary endpoints included the objective response rate (ORR), disease control rate (DCR), overall survival (OS), and safety. Efficacy was evaluated using the Response Evaluation Criteria in Solid Tumors (RECIST) v1.1 criteria, and safety was assessed by Common Terminology Criteria for Adverse Events (CTCAE) v5.0. Results: A total of 133 patients were included in the study (regardless of first-line treatment), including 94 who received regorafenib plus PD-1 inhibitors and 39 who received regorafenib. The regorafenib plus PD-1 inhibitors group had a significantly higher ORR (25.53% vs. 10.26%, P=0.015), higher DCR (87.23% vs. 66.67%, P=0.006), and longer PFS (median 9.0 vs. 4.0 months, P<0.0001) than the regorafenib group. Meanwhile, the median OS (mOS) did not differ between the regorafenib plus PD-1 and regorafenib monotherapy groups {mOS, 14.0 months [95% confidence interval (CI), 14.0-16.0 months] vs. 12.0 months (95% CI, 10.0-22.0 months)}. There was no notable difference in the total incidence of treatment-related adverse effects (TRAEs) (71.79% vs. 78.72%, P=0.39) and the incidence of grade 3/4 serious adverse effects (5.13% vs. 18.09%, P=0.19) between the regorafenib monotherapy group and PD-1 inhibitors combination group. Conclusions: Compared with regorafenib alone, regorafenib combined with PD-1 inhibitors therapy increased PFS, ORR but did not improve OS, and can be used an option in second-line HCC therapy, regardless of first-line treatments. Regorafenib combined with PD-1 inhibitors is recommended as early as a second-line therapy to benefit patients. The combination regimen was as safe as regorafenib monotherapy for treatment of HCC in patients with compensated liver disease [Child-Turcotte-Pugh (CTP) A/B].

Comparison of hepatitis B virus reactivation in hepatocellular carcinoma patients who received tyrosine kinase inhibitor alone or together with programmed cell death protein-1 inhibitors.

BACKGROUND AND AIMS: Programmed cell death protein-1 (PD-1) inhibitors plus tyrosine kinase inhibitor (TKI) have dramatically improved survival of patients with advanced hepatocellular carcinoma (HCC). However, the risk of hepatitis B virus (HBV) reactivation from these antitumor medications remains unclear. METHODS: Patients receiving TKI monotherapy (TKI group) or TKI combined with PD-1 inhibitors (combination group) were included. The primary endpoint was HBV reactivation as defined by an increase in HBV DNA titer by at least 1 log (tenfold) from baseline. The secondary endpoints included tumor progression and overall survival. RESULTS: Four hundred and ninety-nine patients met the inclusion criteria, including 296 patients in the TKI group and 203 patients in the combination group. The 3-, 6- and 12-month cumulative incidence rates of HBV reactivation in the TKI group vs. combination group were 7.8%, 12.8% and 21.3% vs. 9.9%, 19.2% and 30.0%, respectively (p = 0.02). The Cox proportional hazard model indicated that combination therapy (HR 1.41, 95% CI 1.00-1.99, p = 0.05), ALT > 40 U/ml (HR 1.50, 95% CI 1.05-2.16, p = 0.03), and tumor size > 5 cm (HR 1.58, 95% CI 1.10-2.28, p = 0.01) were independent risk factors for HBV reactivation. Compared with the HBV reactivation group, the progression-free survival and overall survival of patients in the HBV non-reactivation group were significantly prolonged (p < 0.001 and p = 0.001). CONCLUSIONS: Patients who received TKI combined with PD-1 inhibitors had a greater risk for HBV reactivation, and those with HBV reactivation had a higher rate of tumor progression and shorter survival time, than those receiving TKI alone.

TKI or TKI combined with PD-1 inhibitors as second-line treatment for HCC patients after sorafenib failure.

Background: Tyrosine kinase inhibitors (TKI) in combination with programmed cell death-1 (PD-1) inhibitors become the potential treatment modality for patients undergoing unresectable hepatocellular carcinoma (uHCC) in the first-line setting. However, the efficacy and safety of this combination regimen in patients after sorafenib failure remains unclear. Methods: Participants in this study included patients with uHCC after sorafenib failure who received TKI monotherapy (TKI group) or TKI combined with PD-1 inhibitors therapy (combination group) in our center from July 2018 to July 2021. The overall survival (OS) was used to be the primary efficacy endpoint, while progression-free survival (PFS), objective response rate (ORR), and disease control rate (DCR) were applied to be secondary endpoints. In addition, the adverse events are recorded and evaluated. Results: Among the 92 patients contained in this work, 50 patients were categorized into the TKI group, while 42 patients were in the combination group. There existed no evident differences between the two groups concerning the ORR (8.0% vs. 9.5%, p = 1.000). However, the DCR in the combined group was better in relative to that in the TKI group (71.4% vs. 50.0%, p = 0.037). In comparison with the TKI group, it was found that the combination group presented notably better median PFS (8.1 months vs. 4.7 months, p = 0.005) and median OS (21.9 months vs. 16.6 months, p = 0.042). According to multivariate analysis, PFS (HR 0.5, 95% CI: 0.3-0.8, p = 0.005) and OS (HR 0.5, 95% CI: 0.3-1.0, p = 0.051) were improved in the combination group in relative to the TKI group after the adjustment for some risk factors. Additionally, the incidence rates of grade ≥1 adverse event in the TKI group and the combination group were 96.0% and 97.6%, respectively. The most normal adverse event in the TKI group was neutropenia (n = 24,48.0%) and the combination group was hypoalbuminemia (n = 23,54.8%). All of these adverse events improved after symptomatic treatment, and no new toxic events were found to occur. Conclusion: TKI combined with PD-1 inhibitors showed better prognosis with manageable toxicity in uHCC patients after sorafenib failure compared with TKI monotherapy.

Development and Validation of a nomogram for forecasting survival of alcohol related hepatocellular carcinoma patients.

Background: With the increasing incidence and prevalence of alcoholic liver disease, alcohol-related hepatocellular carcinoma has become a serious public health problem worthy of attention in China. However, there is currently no prognostic prediction model for alcohol-related hepatocellular carcinoma. Methods: The retrospective analysis research of alcohol related hepatocellular carcinoma patients was conducted from January 2010 to December 2014. Independent prognostic factors of alcohol related hepatocellular carcinoma were identified by Lasso regression and multivariate COX proportional model analysis, and the nomogram model was constructed. The reliability and accuracy of the model were assessed using the concordance index(C-Index), receiver operating characteristic (ROC) curve and calibration curve. Evaluate the clinical benefit and application value of the model through clinical decision curve analysis (DCA). The prognosis was assessed by the Kaplan-Meier (KM) survival curve. Results: In sum, 383 patients were included in our study. Patients were stochastically assigned to training cohort (n=271) and validation cohort (n=112) according to 7:3 ratio. The predictors included in the nomogram were splenectomy, platelet count (PLT), creatinine (CRE), Prealbumin (PA), mean erythrocyte hemoglobin concentration (MCHC), red blood cell distribution width (RDW) and TNM. Our nomogram demonstrated excellent discriminatory power (C-index) and good calibration at 1-year, 3-year and 5- year overall survival (OS). Compared to TNM and Child-Pugh model, the nomogram had better discriminative ability and higher accuracy. DCA showed high clinical benefit and application value of the model. Conclusion: The nomogram model we established can precisely forcasting the prognosis of alcohol related hepatocellular carcinoma patients, which would be helpful for the early warning of alcohol related hepatocellular carcinoma and predict prognosis in patients with alcoholic hepatocellular carcinoma.

Research progress of clinical intervention and nursing for patients with post-stroke dysphagia.

Post-stroke dysphagia (PSD) is a common and costly complication of stroke and is associated with increased mortality, morbidity, and hospitalization. Although most patients can spontaneously resume swallowing, there are still many patients who do not recover and even die. Despite multiple advances in the acute treatment and secondary prevention of stroke, the effective treatment of PSD remains a neglected area. Studies have shown that repair mechanisms of neurostimulation techniques and increased cortical activity play an important role in the treatment of PSD. In addition, nutritional interventions are also crucial for the treatment of malnutrition in PSD patients. Therefore, this article reviews the effects of the current main clinical treatment methods and nutritional interventions on the treatment and rehabilitation of PSD patients. It also emphasized the necessity of developing an individualized care plan for PSD patients, which is of great significance to promote the clinical treatment, nutritional status, prognosis, and quality of life of PSD patients.

The advanced development of molecular targeted therapy for hepatocellular carcinoma.

Hepatocellular carcinoma (HCC), one of the most common malignant tumors in China, severely threatens the life and health of patients. In recent years, precision medicine, clinical diagnoses, treatments, and innovative research have led to important breakthroughs in HCC care. The discovery of new biomarkers and the promotion of liquid biopsy technologies have greatly facilitated the early diagnosis and treatment of HCC. Progress in targeted therapy and immunotherapy has provided more choices for precise HCC treatment. Multiomics technologies, such as genomics, transcriptomics, and metabolomics, have enabled deeper understanding of the occurrence and development mechanisms, heterogeneity, and genetic mutation characteristics of HCC. The continued promotion and accurate typing of HCC, accurate guidance of treatment, and accurate prognostication have provided more treatment opportunities and prolonged survival timelines for patients with HCC. Innovative HCC research providing an in-depth understanding of the biological characteristics of HCC will be translated into accurate clinical practices for the diagnosis and treatment of HCC.

Risk Factors for Hepatic Encephalopathy in Hepatocellular Carcinoma After Sorafenib or Lenvatinib Treatment: A Real-World Study.

Purpose: This study aimed to investigate the incidence rate and risk factors for hepatic encephalopathy (HE) among unresectable hepatocellular carcinoma (uHCC) patients with liver cirrhosis who received sorafenib or lenvatinib treatment. Patients and Methods: uHCC patients with cirrhosis who received first-line sorafenib or lenvatinib treatment between September 2014 and February 2021 were continually reviewed in our single-center retrospective study. The Hepatic Encephalopathy Scoring Algorithm was used to evaluate the occurrence and grade of HE during treatment, and logistic regression models were used to further explore the risk factors for HE. Results: A total of 454 eligible patients were enrolled in our study, with 214 and 240 patients in the sorafenib and lenvatinib groups, respectively. At time of data cut-off (2021-12), the incidence of HE in sorafenib group (4.2%, 95% CI:2-7%) was significantly lower than that in lenvatinib group (11.3%,95% CI:7-15%) (p = 0.006), with alcoholic cirrhosis [OR: 5.857 (95% CI: 1.519-22.591)], Child-Pugh >7 [OR: 3.023 (95% CI: 1.135-8.053)], blood ammonia ≥38.65 µmol/L [OR: 4.693 (95% CI: 1.782-12.358)], total bile acid ≥29.5 µmol/L [OR: 11.047 (95% CI: 4.414-27.650)] and duration of treatment ≥5.6 months [OR: 4.350 (95% CI: 1.701-11.126)] to be risk factors for the occurrence of HE during first-line systemic therapy. Conclusion: In our study, for off-label uHCC patients (Child-Pugh >7) with alcoholic cirrhosis, hyperammonemia, hypercholesterolemia, and estimated longer duration of treatment, the application of lenvatinib has to be cautious, which needs to be confirmed in future clinical trials.

Complete Response to PD-1 Inhibitor in Primary Hepatocellular Carcinoma Patients Post-Progression on Bi-Specific Antibody Conjugated CIK Cell Treatment: A Report of Two Cases.

BACKGROUND: Programmed death receptor-1 (PD-1) immune checkpoint inhibitors (ICIs) have produced encouraging results in hepatocellular carcinoma (HCC) patients. Cytokine-induced killer (CIK) cells treatment can specifically identify tumor-associated antigens and has encouraging preliminary efficacy for HCC. This study reported two cases of HCC patients achieved complete response (CR) by anti-PD-1 antibody therapy post-progression on bi-specific antibody conjugated CIK immunotherapy. CASE PRESENTATION: Case one, a 75-year-old male, was diagnosed with the intrahepatic cholangiocarcinoma (ICC) in October 2017. After interventional, CIK, ablation and other comprehensive therapy, ICC was gradually cured. When new occurrence of HCC, he was treated with anti-PD-1 antibody therapy and achieved CR. Case two, a 65-year-old female, was diagnosed with HCC in July 2016. After progression on several ablation treatments, she received 8 cycles of CIK treatment and achieved stable disease (SD). After disease progressed on CIK treatment, she received 4 cycles of anti-PD-1 antibody therapy, finally achieved CR. CONCLUSION: Anti-PD-1 antibody therapy after prior progression on bi-specific antibody conjugated CIK immunotherapy may be efficacy and safety for HCC patients.

Perioperative safety analysis of transcatheter arterial chemoembolization for hepatocellular carcinoma patients with preprocedural leukopenia or thrombocytopenia.

Patients with hepatocellular carcinoma (HCC) exhibit a high incidence of concomitant cirrhosis with leukopenia and/or thrombocytopenia. In the present study, perioperative changes in the white blood cell (WBC) and platelet (PLT) counts and associated complications were investigated to assess the safety of transcatheter arterial chemoembolization (TACE) for HCC patients with preprocedural leukopenia or thrombocytopenia. The records of 1,461 HCC patients who received TACE between January 2012 and December 2013 were retrospectively reviewed. The incidence of complications during the perioperative period and changes in the WBC and PLT counts were recorded. A Chi-squared test was used to evaluate the associations between postoperative infection and preprocedural WBC count and between bleeding at the puncture site and preprocedural PLT count. The WBC count of the majority of the patients increased within 3 days and returned to the preprocedural level within 30 days after TACE. The PLT count decreased within 3 days and returned to the preprocedural level within 30 days after TACE. The major complications were liver decompensation (n=66), puncture site bleeding (n=45), infection (n=33), severe thrombocytopenia (n=8), upper gastrointestinal bleeding (n=6), tumor bleeding (n=4) and agranulocytosis (n=3). A Chi-squared test revealed that postoperative infection was not associated with preprocedural WBC count and puncture site bleeding was not associated with decreased PLT count due to hypersplenism. Therefore, TACE was found to be safe for HCC patients with preprocedural thrombocytopenia or leukopenia due to hypersplenism, with a low incidence of major complications during the perioperative period.

Acquired amegakaryocytic thrombocytopenic purpura induced by percutaneous ethanol injection during treatment of hepatocellular carcinoma: A case report.

Percutaneous ethanol injection is an important localized treatment method for patients presenting with hepatocellular carcinoma (HCC). Among the advantages of percutaneous ethanol injection are its minimal invasiveness, simplicity, low cost and low risk of complications. However, the increasing popularity of percutaneous ethanol injection has resulted in serious adverse effects attributed to individual variations. The present study describes the case of a patient who exhibited acquired amegakaryocytic thrombocytopenic purpura, caused by percutaneous ethanol injection treatment for HCC. This complication was promptly identified, and platelet transfusion and injection of recombinant human interleukin-11 resulted in a rapid recovery of the patient's platelet count. Attention should be given to this rare complication in patients administered percutaneous ethanol injection treatment for HCC.

Enhanced therapeutic efficacy of combined use of sorafenib and transcatheter arterial chemoembolization for treatment of advanced hepatocellular carcinoma.

OBJECTIVE: Clinical trials suggest that combining transcatheter arterial chemoembolization with sorafenib in patients with advanced hepatocellular carcinoma shows a superior safety and tolerability profile. Our study aimed to retrospectively analyze the utility and prognostic factors of this combined therapy in these patients. METHODS: Patients with advanced hepatocellular carcinoma, treated by transcatheter arterial chemoembolization and sorafenib subsequently, between February 2010 and September 2012 in our hospital, were retrospectively analyzed. After sorafenib treatment for 12 weeks, abdominal enhanced computed tomography or magnetic resonance imaging was used to evaluate short-term outcomes and clinical benefit rate. Overall survival and adverse events were recorded during follow-up. Univariate and multivariate analyses were used to identify relationships between baseline characteristics and overall survival. RESULTS: Fifty-one advanced hepatocellular carcinoma patients were included. Common adverse events for sorafenib were hand-foot skin reaction, alopecia, diarrhea, anorexia and fatigue. The clinical benefit rate was 64% and the median survival time was 7.5 months. Median survival of patients with and without portal vein tumor thrombi was 6.0 months and 10.3 months (P < 0.001), respectively. Median survival of patients with cholinesterase ≥5000 U/l and < 5000 U/l was 10.6 months and 6.1 months (P < 0.001), respectively. Multivariate analysis identified the presence of portal vein tumor thrombi and low cholinesterase level as independent negative predictors of survival. CONCLUSIONS: Combining sorafenib and transcatheter arterial chemoembolization was safe and effective for advanced hepatocellular carcinoma patients with extrahepatic spread but without portal vein tumor thrombi. Portal vein tumor thrombi and cholinesterase level are independent predictors of prognosis following this combined therapy.

Solution of AntiSeepage for Mengxi River based on numerical simulation of unsaturated seepage.

Lessening the leakage of surface water can reduce the waste of water resources and ground water pollution. To solve the problem that Mengxi River could not store water enduringly, geology investigation, theoretical analysis, experiment research, and numerical simulation analysis were carried out. Firstly, the seepage mathematical model was established based on unsaturated seepage theory; secondly, the experimental equipment for testing hydraulic conductivity of unsaturated soil was developed to obtain the curve of two-phase flow. The numerical simulation of leakage in natural conditions proves the previous inference and leakage mechanism of river. At last, the seepage control capacities of different impervious materials were compared by numerical simulations. According to the engineering actuality, the impervious material was selected. The impervious measure in this paper has been proved to be effectible by hydrogeological research today.

Numerical simulation on open wellbore shrinkage and casing equivalent stress in bedded salt rock stratum.

Most salt rock has interbed of mudstone in China. Owing to the enormous difference of mechanical properties between the mudstone interbed and salt rock, the stress-strain and creep behaviors of salt rock are significantly influenced by neighboring mudstone interbed. In order to identify the rules of wellbore shrinkage and casings equivalent stress in bedded salt rock stratum, three-dimensional finite difference models were established. The effects of thickness and elasticity modulus of mudstone interbed on the open wellbore shrinkage and equivalent stress of casing after cementing operation were studied, respectively. The results indicate that the shrinkage of open wellbore and equivalent stress of casings decreases with the increase of mudstone interbed thickness. The increasing of elasticity modulus will reduce the shrinkage of open wellbore and casing equivalent stress. Research results can provide the scientific basis for the design of mud density and casing strength.

[Study on MSO/GO-based determination method for trace amount of aqueous Hg2+].

OBJECTIVE: To establish a highly sensitive fluorometric nanobiosensor for determination of aqueous mercury ions (Hg(2+)) using optimized mercury-specific oligonucleotide (MSO) probes and graphene oxide (GO). METHODS: The nanobiosensor was assembled by attaching the self-designed MSO(1) (5' end labeled with fluorophore carboxyfluorescein (FAM), denoted as FAM-MSO(1)) and MSO(2) to the surface of GO through strong non-covalent bonding forces. Upon the addition of Hg(2+), the formation of the T-Hg(2+)-T configuration desorbed the FAM-MSO(1) and MSO(2) from the surface of GO, resulting in a restoration of the fluorescence of FAM-MSO(1). Using the specific mispairing of T-Hg(2+)-T and the changes in fluorescent signals in solutions, quantitative analysis of Hg(2+) could be performed. RESULTS: The average thickness of the prepared GO sheets was only 1.4 nm. For the Hg(2+) nanobiosensor, the optimum concentrations of FAM-MSO(1) and MSO(2) were both 1 µmol/L, the optimum volume of 0.5 g/L GO was 5 µL, and the limit of detection was 10 pmol/L; it had low cross-reactivity with 10 other kinds of non-specific metal ions; the fluorescence recovery efficiency was up to 65% in the re-determination of Hg(2+) after addition of Na(2)S(2)O(3). CONCLUSION: The MSO/GO-based nanobiosensor is convenient to operate, highly sensitive, highly specific, highly accurate, and reusable. It can be applied to determine trace amount of Hg(2+) in aqueous solutions.