A simple and sensitive electrochemical sensor for the detection of peptidase activity.

In this work, a simple and sensitive electrochemical sensor was proposed for the detection of ß-site amyloid precursor protein cleaving enzyme 1 (BACE1) activity. Firstly, the BACE1 specific peptide was modified onto the Au electrode to graft a single-strand DNA with polycytosine DNA sequence (dC12) via amide bonding between peptide and dC12. Because the dC12 is abundant in phosphate groups, thus it can react with molybdate to form redox molybdophosphate, which can generate electrochemical current. Using BACE1 as a model peptidase, the proposed sensor shows a linear response range from 1 to 15 U/mL and limit of detection down to 0.05 U/mL. The sensor displays good performance for the BACE1 activity detection in human serum samples, which may have potential applications in the clinical diagnostics of Alzheimer's disease.

A "signal-on" photoelectrochemical sensor for human epidermal growth factor receptor 2 detection based on Y6/CdS organic-inorganic heterojunction.

A "signal-on" photoelectrochemical (PEC) immunosensor was successfully constructed for determination of human epidermal growth factor receptor 2 (HER2) based on organic-inorganic heterojunction Y6/CdS as photoactive material. Compared with single organic semiconductor, Y6, Y6/CdS exhibited higher photoelectric conversion efficiency due to the formation of heterojunction. In the presence of HER2, sandwich immune structure was formed between HER2 aptamer and anti-HER2 antibody (Ab) by specific recognition. The polydopamine (PDA) nanoparticles were used for signal amplification to enhance photocurrent intensity as PDA can act as electron donor to eliminate holes and promote electron-hole pairs separation. The developed PEC sensor displayed a wide detection range of 5-1000 pg mL-1 and a low detection limit of 2.2 pg mL-1 for HER2 (S/N = 3). The sensor was successfully used for the detection of HER2 in serum with recoveries between 94.8 and 104% and relative standard deviations (RSDs) in the range of 1.2-4.3%. Furthermore, the designed immunosensor possessed good stability, selectivity, and reproducibility, which can find potential clinical applications for disease diagnosis. A "signal-on" photoelectrochemical sensor was reported for human epidermal growth factor receptor 2 detection based on Y6/CdS organic-inorganic heterojunction.

Photoelectrochemical assay for the detection of circulating tumor cells based on aptamer-Ag2S nanocrystals for signal amplification.

In this work, we developed a photoelectrochemical assay for circulating tumor cells (CTCs) detection based on hexagonal carbon-nitrogen tubes (HCNT) as visible light-sensitive materials. The MCF-7 cell was selected as the model CTC and was captured through specific recognition between epithelial cell adhesion molecules (EpCAM) on the cell surface and anti-EpCAM antibodies. Anti-EpCAM antibody-modified magnetic nanoparticles were used to enrich and separate MCF-7 cells from samples. The detection signal was amplified by Ag2S nanocrystals, which can compete with HCNTs for absorbing visible light, leading to a decrease of photocurrent intensity. The linear range of the assay for MCF-7 cells is from 10 to 5000 cells mL-1, with a detection limit of 3 cells mL-1 (S/D = 3). The assay has good selectivity for MCF-7 detection over HeLa cells. The assay was successfully applied for the detection of MCF-7 in human whole blood, which indicates the potential for clinical application.

Photoelectrochemical detection of human epidermal growth factor receptor 2 (HER2) based on Co3O4-ascorbic acid oxidase as multiple signal amplifier.

A sensitive photoelectrochemical (PEC) sensor based on hexagonal carbon nitride tubes (HCNT) as photoactive material was prepared for the detection of human epidermal growth factor receptor 2 (HER2). Magnetic Fe3O4 nanospheres (MNs) modified with anti-HER2 antibodies were employed for highly efficient capture of HER2 from serum sample, and Co3O4 nanoparticles (Co3O4 NPs) modified with ascorbic acid oxidase (AAO) as well as HER2 aptamer were used for signal amplification. When the aptamer-Co3O4-AAO probe was captured onto the electrode surface through the specific binding of the aptamer with HER2, the photocurrent intensity decreased. This was because Co3O4 NPs competed with HCNT for consumption of the excitation energy. As a consequence AAO catalyzed the oxidation of the electron donor (AA), and the aptamer-Co3O4-AAO probe increased the steric hindrance at the electrode surface, leading to significant photocurrent intensity decrease, thus realizing multiple signal amplification. Based on this signal amplification strategy, at 0 V (vs Ag/AgCl), the PEC sensor shows a wide linear response ranging from 1 pg mL-1 to 1 ng mL-1 with a low detection limit of 0.026 pg mL-1 for HER2. Importantly, the prepared PEC sensor was applied for detection of HER2 in human serum samples with recoveries between 98.8 and 101%. Sensitive photoelectrochemical sensor based on Co3O4 nanoparticles modified with ascorbic acid oxidase for signal amplification is reported.

The clinical study of fast-track rehabilitation nursing in the perioperative period of therapeutic laparoscopy of colon cancer patients.

OBJECTIVE: To explore the clinical application of fast-track rehabilitation nursing in the perioperative period of therapeutic laparoscopy of colon cancer patients. METHODS: Patients with colorectal cancers who were hospitalized in the Department of Oncology and General Surgery of The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University from August 2016 to December 2018 were selected as the research subjects of the study. All the research subjects were divided into the study group 1(n=29), the study group 2(n=29) and the control group (n=24). The control group received routine nursing during the perioperative period, and the research group 1 and 2 received rapid rehabilitation nursing during the perioperative period. Postoperative comparison was made between the two groups on the differences in the time of the first time out of bed, the time of the first anal exhaust, and the time of the first feeding. The differences of pain control in each group after nursing care were evaluated by the pain scale, and the degree of satisfaction of each group was evaluated by the satisfaction scale. RESULTS: In terms of the basic information of patients, the experimental results had indicated no significant statistical difference among the study group 1, the study group 2, and the control group (P>0.05). By analysing the postoperative physical condition indicators of patients, the time of first off-bed activity, the time of first anal exhaust, and the first time of food intake of patients in the observation group 1 and the observation group 2 were significantly different (P<0.05) as compared with the control group. Besides that, the postoperative pain scale and pain satisfaction of patients were observed, in which the difference in pain scales at each 6h, 12h, 24h, and 48h after the surgeries were statistically significant (P<0.05). In terms of the satisfaction of pain control or pain relief, the differences were statistically significant (P<0.05). CONCLUSIONS: Therefore, it was concluded that the fast-track rehabilitation nursing could promote the treatment of colon cancer patients. Despite the deficiencies of the experimental processes, the study has provided the good results on fast-track rehabilitation nursing with a reliable theoretical basis.

Gold nanoparticle-modified black phosphorus nanosheets with improved stability for detection of circulating tumor cells.

Gold nanoparticle (AuNP)-anchored BP nanosheets were synthesized through in situ growth of AuNPs onto BP. Due to the strong chelating ability of P or phosphorus oxides with AuNPs, the stability of BP is improved. As proof-of-concept demonstration of the functionalized BP, electrochemical detection of circulating tumor cells (CTCs) based on BP@AuNPs@aptamer as a probe combined with immunomagnetic separation is reported. The aptamer can specifically bind with CTCs, while the phosphorus oxides including phosphite ion and phosphate ion (PxOy species) on BP and aptamer can react with molybdate to generate an electrochemical current, leading to dual signal amplification. The biosensor is applied to MCF-7 cell detection and displays good analytical performance with a detection limit of 2 cell mL-1. Furthermore, the practicality of this biosensor was validated through sensitive determination of MCF-7 cells in human blood. Therefore, the reported biosensor could be applied to detect other biomarkers, offering an ultrasensitive strategy for clinical diagnostics. Graphical abstract Electrochemical detection of circulating tumor cells based on gold nanoparticle-modified black phosphorus nanosheets is reported.

Aptamer-based photoelectrochemical assay for the determination of MCF-7.

In this work, an aptamer-based photoelectrochemical (PEC) assay is reported for the determination of MCF-7 breast cancer cells using hexagonal carbon nitride tubes (HCNTs) as photoactive material. The aptamer immobilized on the HCNT surface can specifically bind with mucin 1 protein (MUC1) that is overexpressed on the surface of MCF-7 cell. Thus, the PEC assay has high specificity for the determination of MCF-7. The determination of MCF-7 is due to the binding of MCF-7 onto HCNT that suppressed the photocurrent intensity. The PEC assay displays good performances for MCF-7 determination with a linear range from 1 × 102 to 1 × 105 cell mL-1 and limit of detection down to 17 cells mL-1. Meanwhile, the PEC assay can distinguish MCF-7 from normal cells in blood samples, which may have potential applications in cancer diagnostics and therapeutics.

Photoelectrochemical detection of circulating tumor cells based on aptamer conjugated Cu2O as signal probe.

In this work, a sensitive and reliable photoelectrochemical (PEC) biosensor was proposed based on hexagonal carbon nitride tubes (HCNT) as photoactive material for detection of circulating tumor cells (CTCs). Magnetic Fe3O4 nanospheres (MNs) and Cu2O nanoparticles (Cu2O NPs) were utilized for highly efficient magnetic capture of CTCs and for signal amplification, respectively. First, anti-epithelial cell adhesion molecule (EpCAM) antibody was linked onto MNs for capture and enrichment of CTCs. With the captured MCF-7 coated onto the electrode, the photocurrent intensity of HCNT was decreased due to the steric hindrance derived from MCF-7. Then, when the Cu2O-aptamer probe was bound onto the CTC surface, the photocurrent intensity was further decreased because Cu2O NPs competed with HCNT for absorption of exciting light and the aptamer molecules increased the steric hindrance, which leads to significantly decreased photocurrent response, thus realizing dual signal amplification. Using the breast cancer cell MCF-7 as a model, the proposed PEC biosensor displays good performances with a linear range from 3 to 3000 cell mL-1 and limit of detection down to 1 cell mL-1. The HCNT-based PEC biosensor shows good performance for detection of CTCs, which may have potential applications in cancer diagnostics and therapeutics.

Photoelectrochemical detection of breast cancer biomarker based on hexagonal carbon nitride tubes.

Photoelectrochemical (PEC) sensor for sensitive detection of breast cancer biomarker human epidermal growth factor receptor 2 (HER2) utilizing hexagonal carbon nitride tubes (HCNT) as photoactive material is reported. The detection is based on suppression of the PEC current intensity of the sensor. HCNT were synthesized via a facile hydrothermal method with large specific surface area and low electron-hole recombination. Au nanoparticles (AuNPs) were deposited onto the surface of the HCNT, which enhanced the photocurrent intensity of the HCNT by one time. For HER2 detection, peptide specific to HER2 was immobilized on the AuNPs surface for capturing HER2 molecules. The following binding of HER2 with HER2 aptamer and the reaction of phosphate groups on aptamer with molybdate can form molybdophosphate precipitate, which sticks to the surface of HCNT and impedes electron transport. Thus, photocurrent intensity of the sensor was suppressed. Under optimal conditions, the linear relationship between the PEC intensity and the logarithm of HER2 concentration was from 0.5 to 1 ng mL-1 with low limit of detection (LOD) of 0.08 pg mL-1. Furthermore, the PEC sensor also displayed capability for detecting HER2 in human serum samples. This PEC sensor signal detection strategy can be easily adapted to other PEC sensors involving DNA and find wide applications. Graphical abstract.

Self-Assembled DNA Generated Electric Current Biosensor for HER2 Analysis.

We have developed a new DNA self-assembly amplification technology that generates electric current for electrochemical biosensing. The new technology was used for detection of human epidermal growth factor receptor 2 (HER2). In our technology, an aptamer was utilized both as a ligand for recognition and as a signal generating reporter. The aptasensor is based on a sandwich format and a DNA primer on a HER2 aptamer initiates auxiliary DNA self-assembled on the electrode to form a long one-dimensional DNA. The resulting DNA is then reacted with molybdate to generate electrochemical current. The sensitivity of the aptasensor with DNA self-assembly was greater than that of the aptasensor without DNA self-assembly due to the extended length of the DNA strand. Aptasensor analysis of HER2 in serum of breast cancer patients and healthy individuals is highly correlated (R2 = 0.9924) with ELISA measurements, with a p value of 1.37 × 10-7. The analysis of HER2 in serum (confirmed by ELISA) suggests that HER2 levels in breast cancer patients are much higher than healthy individuals. For HER2 positive patients, the levels are higher than those of HER2 negative patients. After surgery, there is a drop of HER2 levels in serum, suggesting potential clinical applications of the new self-assembled DNA electric current generating biosensor. Unlike proteins, DNA is easily amplifiable. The DNA signal amplification method presented here enables effective current generation, which can find wide range of biomedical applications for protein detection.

[Three-column plate internal fixation for the treatment of complex tibial plateau fracture through antero-midline and postero-medial approaches].

OBJECTIVE: To study technique and clinical therapeutic effects of internal fixation with three-column plates for the treatment of complex tibial plateau fractures through antero-midline and postero-medial approaches. METHODS: From January 2010 to December 2012, 28 patients with complex tibial plateau fractures were treated with internal fixation using three-column plates through antero-midline and postero-medial approaches. There were 17 males and 11 females, with an average age of 45.3 years old (ranged, 28 to 64 years old). Twelve patients had injuries in the left side and 16 patients had injuries in the right side. According to Schatzker classification, 12 patients were type V, 16 patients were type VI. According to three-column classification, all the patients had injuries of lateral, medial and posterior columns. The mean interval from injury to operation was 9.4 days (ranged, 6 to 15 days). The main clinical symptoms were knee joint swelling, deformity and limitation of motion before operation. The X-ray and CT showed all patients had complex tibial plateau fractures, which involved in the lateral, medial and posterior columns. The therapeutic effects were evaluated by fracture healing time, hospital for special surgery knee score (HSS) at one year after operation. The indexes such as tibial plateau-tibial shaft angle (TPA), posterior slope angle (PA) and femoral-tibial angle (FfA) were compared between immediate postoperation and one year after operation. RESULTS: All incisions primarily healed without postoperative complications such as infection and cutaneous necrosis. All the patients were followed up, and the duration ranged from 12 to 24 months, with a mean of 18.1 months. The bone union time ranged from 5 to 10 months (mean, 7.8 months) after operation. Knee joint swelling and pain disappeared after bony union, and joint function completely recovered. The results of hospital for special surgery knee score (HSS) was 27.81 ± 2.17 in pain, 19.52 ± 2.05 in function,15.82 ± 1.73 in passive range of motion, 8.51 ± 1.32 in muscle strength, 8.33 ± 1.08 in flexion deformity, 9.36 ± 0.52 in joint stability, and the total mean score was 89.35 ± 3.19. According to results of HSS, 20 patients got an excellent result, 5 good,2 fair and 1 poor. There were no significant differences in tibial plateau-tibial shaft angle (TPA), posterior slope angle (PA) and femoral-tibial angle (FTA) between immediate postoperation and one year after operation. CONCLUSION: Three-column plate internal fixation for the treatment of complex tibial plateau fractures through antero-midline and posteromedial approaches is effective to achieve anatomic reduction,rigid internal fixation and early functional exercise.

[Effects of Huoxue Zhitong decoration on transmembrane protein I and II induced apoptosis of signal transmission of the epidural scar tissue].

OBJECTIVES: To study the effect of Houxue Zhitong decoration on the expression of the mitochondria-initiated apoptosis pathway and transmembrane protein I an II of the epidural scar tissue. METHODS: A total of 60 New Zealand rabbits (weight: 2.5-3.0 kg) were randomly divided into four groups, sham operation group (D, n=15), control group (B, n=14), sodium hyaluronate group (C, n=15), Houxue Zhitong decoration group (D, n=15). Except for group A, 1.0 cm x 1.0 cm dura mater uncovered area laminectomy was performed at I (4) and I(5), covered with 0.5 ml sodium hyaluronate in group C, covered with same amount of saline in group B and D. First 2 weeks after operation, animals in group D were lavaged with 2.5 ml/kg Houxue Zhitong decoction by one a day for 14 days. Five rabbits of each group selected randomly were killed in the 2,4,8 weeks after laminectomy. The specimens were prepared for determination of the expression of Fas and FasL, at scar tissue by semiquantitative reserve transcription-polymerase chain reaction (RT-PCR). The degree of scar adhesion was evaluated according by Rydell method. RESULTS: The adhesion area in group B was larger than of group C and D in the 4th and 8th week. However, the number of fibroblasts and inflammantory cells in group D was the least among the three groups in the 8th week. At 2, 4, 8 weeks after operation, as compared with group B the expression of Fas, FasL of group C and D were decreased (P < 0.05). Especially, at 2 weeks, as compared with group B the expression of this two cytokines of group D was significant decreased (P < 0.05), too. In group C and D the duramater adhesion was decreased (P < 0.05). The proliferation of fibroblast and fibroblastic function were inhibited (P < 0.05). CONCLUSION: Huoxue Zhitong is able to down-regulated the expression of Fas, FasL, which inhibited the proliferation of fibroblast, the fibroblastic function and the synthesis of extracellular matrix in the epidural scar tissue. It is an effective way of reducing peridural scar formation and prevent the failed back surgery syndrome.

[Effects of Huoxuezhitong recipe on the pathway of mitochondrial apoptosis and the expression of related gene in epidural scar tissue].

OBJECTIVE: To study the effect of Huoxuezhitong recipe on the pathway of mitochondrial apoptosis and the expression of related gene (Caspase-3, -9, Bax, Bcl-2) in epidural scar tissue. METHODS: A total of 60 New Zealand rabbits, ranging in weight from 2.5 to 3.0 kg, were randomly divided into sham operative group (group A), control group (group B), sodium hyaluronate group (group C), Huoxuezhitong recipe group (group D, included Danggui 20 g, Chishao 20 g, Honghua 20 g, Ruxiang 15 g, Myrrh 15 g etc.) with 15 rabbits in each group. Except for group A, L4,5 vertebral plate were resected leading to 1.0 cm x 1.0 cm dura mater exposed area, which were covered with 0.5 ml sodium hyaluronate in group C, covered with same amount of saline in group B and D. At 2 weeks after operation, the rabbits of group D were administered with Huoxuezhitong recipe (2.5 ml/kg, once a day, continuous 14 d). Five rabbits of each group were selected randomly and were killed at 2, 4 and 8 weeks after operation; and the expression of Caspase-3, -9, Bax, Bcl-2 in scar tissue were surveyed by semiquantitative reverse transcription-polymerase chain reaction (RT-PCR). RESULTS: The results by RT-PCR showed significant different in expressions of Caspase-3, -9, Bax, Bcl-2 of group A and others groups at each period (P < 0.01). At 2, 4, 8 weeks after operation, compared with group B, the expressions of Caspase-3, -9, Bcl-2 in group C and D were decreased (P < 0.05), but the expression of Bax in group C and D were increased (P < 0.05). At 8 weeks after operation, the expressions of Caspase-3, -9, Bax, Bcl-2 in group D was significant decreased compared with group C (P < 0.05). CONCLUSION: Huoxuezhitong recipe can regulate the levels of expression of Caspase-3, -9, Bax, Bcl-2 mRNA and further induce the pathway of mitochondrial apoptosis, thereby, achieve the effect of prophylaxis for the proliferation and conglutination of epidural scar tissue.