Detection of Ureaplasma urealyticum by Catalytic Hairpin Assembly Combined with a Lateral Flow Immunoassay Strip.

Ureaplasma urealyticum is a common genital mycoplasma in men and women, which can cause reproductive tract infection and infertility, and is also related to adverse pregnancy outcomes and neonatal diseases. Pathogen culture and polymerase chain reaction (PCR) are the main methods for the diagnosis of U. urealyticum. However, pathogen culture takes too long, and PCR requires professional personnel and sophisticated instruments. Here, we report a simple, convenient, sensitive, and specific detection method, which combines catalytic hairpin assembly with a lateral flow immunoassay strip. Only a water bath and a fluorescence reader are needed to detect the results in 30 min. We can realize the point-of-care testing of U. urealyticum by this method. To verify this method, we selected 10 clinical samples for testing, and the test results were exactly the same as the clinical report.

Facile, Rapid, and Low-Cost Detection for Influenza Viruses and Respiratory Syncytial Virus Based on a Catalytic DNA Assembly Circuit.

Influenza viruses and respiratory syncytial virus (RSV) have contributed to severe respiratory infections, causing huge economic and healthcare burdens. To achieve rapid and precise detection of influenza viruses and RSV, we proposed a catalytic hairpin assembly (CHA) combined with the lateral flow immunoassay (CHA-LFIA) detection method. The presence of the target RNA triggers the initiation of CHA circuits. H1/H2 complexes, the amplified signal products, which were labeled with digoxin and biotin, were detected with a highly sensitive lateral flow immunoassay system. The sensitivity of the CHA-LFIA system to influenza A and B viruses and RSV reached up to 1, 1, and 5 pM, respectively. In addition, this method exhibited excellent capability for differentiating between target RNA and base-mismatched RNA. The results demonstrated that an enzyme-free, rapid, highly sensitive, and specific method had been developed to detect influenza A and B viruses and RSV.

Sensitive detection of hepatitis C virus using a catalytic hairpin assembly coupled with a lateral flow immunoassay test strip.

Currently, PCR is the gold standard for the detection of hepatitis C virus (HCV). However, the PCR technique is complicated and time-consuming, which prevents its application and, clinical point-of-care testing (POCT). Herein, we report a POCT method with simplicity, high sensitivity and specificity, which consists of a catalytic hairpin assembly (CHA) signal amplification system coupled with a lateral flow immunochromatographic (LFIA) test strip for the detection of HCV. Two ingeniously designed hairpin probes were hybridized to form the H1-H2 duplex in the presence of the target DNA. The catalytic hairpin assembly which was characterized of isothermal and enzyme-free, was accomplished within 40 min and the reaction was then applied to a LFIA test strip. Only the H1-H2 duplex labeled with both digoxin and biotin could be captured by the test strip, and the fluorescence value was determined. In addition, we evaluated the application potential for the detection of clinical samples. The reported method demonstrated high sensitivity with a detectable minimum concentration at 1 fM and showed a good linear range from 10 nM to 10pM, and high specificity for various mismatched sequences. The results demonstrated that clinically positive samples could be successfully detected. In conclusion, the reported method is simple, rapid, and free of large-scale equipment. POCT is expected to be useful for HCV detection in clinic.

Rapid point-of-care testing for SARS-CoV-2 virus nucleic acid detection by an isothermal and nonenzymatic Signal amplification system coupled with a lateral flow immunoassay strip.

An outbreak of a new coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), began in December 2019. Accurate, rapid, convenient, and relatively inexpensive diagnostic methods for SARS-CoV-2 infection are important for public health and optimal clinical care. The current gold standard for diagnosing SARS-CoV-2 infection is reverse transcription-polymerase chain reaction (RT-PCR). However, RTPCR assays are designed for use in well-equipped laboratories with sophisticated laboratory infrastructure and highly trained technicians, and are unsuitable for use in under-equipped laboratories and in the field. In this study, we report the development of an accurate, rapid, and easy-to-implement isothermal and nonenzymatic signal amplification system (a catalytic hairpin assembly (CHA) reaction) coupled with a lateral flow immunoassay (LFIA) strip-based detection method that can detect SARSCoV-2 in oropharyngeal swab samples. Our method avoids RNA isolation, PCR amplification, and elaborate result analysis, which typically takes 6-8 h. The entire CHA-LFIA detection method, from nasopharyngeal sampling to obtaining test results, takes less than 90 min. Such methods are simple and require no expensive equipment, only a simple thermostatically controlled water bath and a fluorescence reader device. We validated our method using synthetic oligonucleotides and clinical samples from 15 patients with SARS-CoV-2 infection and 15 healthy individuals. Our detection method provides a fast, simple, and sensitive (with a limit of detection (LoD) of 2000 copies/mL) alternative to the SARS-CoV-2 RT-PCR assay, with 100 % positive and negative predictive agreements.

Clinical characteristics and outcomes of patients with diabetic ketoacidosis of different severity.

To analyze the influencing factors and outcomes of the different severity of diabetic ketoacidosis (DKA).A total of 50 children with DKA admitted to the Department of Pediatrics, Tianjin Medical University General Hospital from January 2009 to December 2018 were included in this study. The patients were divided into mild group, moderate group, and severe group according to the severity of the disease. We then analyzed the clinical characteristics and outcomes of the 3 groups.Compared to mild and moderate DKA groups, patients with severe DKA were more likely to present chest tightness, and higher levels of blood osmotic pressure, urea, and creatinine (P < .05). Logistic regression analysis showed that blood osmotic pressure, creatinine, and chest tightness were independent factors for severity of DKA. There was a significant difference in the resolution time of DKA among the 3 groups (mild vs moderate: 9.0 hours vs 15.25 hours; moderate vs severe: 15.25 hours vs 24.5 hours, P < .001). There were statistical differences in the decline of Glasgow score among 3 groups (P = .004).Patients with severe DKA showed higher osmotic pressure and creatinine, as well as dyspnea. The children with severe DKA were more likely to present progression of neurological symptoms, which was necessary to pay attention to the presence of brain edema.