Smartphone-assisted point-of-care testing of nucleic acids based on hybridization chain reaction, magnetic beads, and gold nanorods etching

Colorimetric biosensors are simple but effective tools that are gaining popularity due to their ability to provide low-cost, rapid, and accurate detection for viruses like the Novel coronavirus, Influenza A, and Dengue virus, especially in point-of-care testing (POCT) and visual detection. In this study, a smartphone-assisted nucleic acid POCT was built using hybridization chain reaction (HCR), magnetic beads (MBs), and oxidized 3,3′,5,5′-tetramethylbenzidine (TMB2+)-mediated etching of gold nanorods (GNRs). The application of HCR without enzyme isothermal characteristics and MBs with easy separation, can quickly amplify nucleic acid signal and remove other reaction components. The blue shift of longitudinal localized surface plasmon resonance (LSPR) based on GNRs showed significant differences in etching color for different concentrations of target nucleic acid, which convert the signal into a visually semi-quantitative colorimetric result, achieving quantitative analysis with the color recognition software built into smartphones. This strategy, which only takes 40 min to detect and is two-thirds less time than the PCR, was successfully applied for the detection of the Dengue target sequence with a detection limit of 1.25 nM and exhibited excellent specificity for distinguishing single-base mutations, indicating broad application prospects in clinical laboratory diagnosis and enriching the research of nucleic acid POCT.

Immunomodulatory Mechanisms of Mesenchymal Stem Cells and Their Potential Clinical Applications.

Mesenchymal stem cells (MSCs) are multipotent stem cells with the capacity of self-renewal, homing, and low immunogenicity. These distinct biological characteristics have already shown immense potential in regenerative medicine. MSCs also possess immunomodulatory properties that can maintain immune homeostasis when the immune response is over-activated or under-activated. The secretome of MSCs consists of cytokines, chemokines, signaling molecules, and growth factors, which effectively contribute to the regulation of immune and inflammatory responses. The immunomodulatory effects of MSCs can also be achieved through direct cell contact with microenvironmental factors and immune cells. Furthermore, preconditioned and engineered MSCs can specifically improve the immunomodulation effects in diverse clinical applications. These multifunctional properties of MSCs enable them to be used as a prospective therapeutic strategy to treat immune disorders, including autoimmune diseases and incurable inflammatory diseases. Here we review the recent exploration of immunomodulatory mechanisms of MSCs and briefly discuss the promotion of the genetically engineered MSCs. Additionally, we review the potential clinical applications of MSC-mediated immunomodulation in four types of immune diseases, including systemic lupus erythematosus, Crohn's disease, graft-versus-host disease, and COVID-19.

An AAV vaccine targeting the RBD of the SARS-CoV-2 S protein induces effective neutralizing antibody titers in mice and canines.

The coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has resulted in catastrophic damage worldwide. Accordingly, the development of powerful, safe, easily accessible vaccines with long-term effectiveness is understood as an urgently needed countermeasure against this ongoing pandemic. Guided by this strong promise of using AAVs, we here designed, optimized, and developed an AAV-based vaccines (including AAV-RBD(max), AAV-RBD(wt), AAV-2xRBD, and AAV-3xRBD) that elicit strong immune responses against the RBD domain of the SARS-CoV-2 S protein. These immunogenic responses have proven long-lived, with near peak levels for at least six months in mice. Notably, the sera immunized with AAV-3xRBD vaccine contains powerful neutralizing antibodies against the SARS-CoV-2 pseudovirus. Further evidence proven that potent specific antibodies could also be elicited in canines after vaccination with AAV-3xRBD vaccine.

Low vaccination coverage of pneumococcal conjugate vaccines (PCVs) in Shanghai, China: A database analysis based on birth cohorts from 2012 to 2020.

BACKGROUND: Pneumococcal vaccines have been developed to protect infants and young children from pneumococcal diseases. Vaccination coverage studies are important in determining a population's vaccination status and strategically adjusting national immunization programs (NIP). In this paper, we aim to describe the coverage of pneumococcal conjugate vaccines (PCVs) immunization for birth cohorts from 2012 to 2020 and discussed the factors influencing the coverage. METHODS: Vaccination data were collected via the vaccination information database in Shanghai, China, for children born from 2012 to 2020. The population data used in this study were collected from each community from 2012 to 2020. The coverage of initial immunization (1st dose), basic immunization (three doses) and full immunization (3 + 1 doses) for PCVs was calculated according to the number of doses received. As vaccination coverage was assessed each year, Annual Growth Rate (AGR) was used to describe the variation trend of vaccination coverage. Immunization time and completeness of different PCVs were also analyzed. RESULTS: The total number of births from 2012 to 2020 was 38,268 in Huangpu District, Shanghai, China. The initial immunization coverage of PCVs increased from 12.26% in 2012 to 49.65% in 2020, and the highest coverage was 50.61% in 2019. The cumulative vaccination coverage of PCVs was 19.4% for initial immunization and 16.8% for basic immunization from 2012 to 2020. And cumulative full immunization coverage of PCVs was 12.3% from 2012 to 2019. The PCVs coverage of most vaccination statuses showed an obvious upward trend from 2017 to 2020. CONCLUSIONS: Despite an upward trend in vaccination coverage of PCVs, the vaccination coverage of initial, basic and full immunization among children is still low. And given the heavy burden of Streptococcus pneumoniae (Sp) among children in China and the fact that the current vaccination coverage cannot effectively protect children, it is recommended that the government include PCVs into the NIP as soon as possible.

High-Precision Temperature Inversion Algorithm for Correlative Microwave Radiometer.

In order to achieve high precision from non-contact temperature measurement, the hardware structure of a broadband correlative microwave radiometer, calibration algorithm, and temperature inversion algorithm are innovatively designed in this paper. The correlative radiometer is much more sensitive than a full power radiometer, but its accuracy is challenging to improve due to relatively large phase error. In this study, an error correction algorithm is designed, which reduces the phase error from 69.08° to 4.02°. Based on integral calibration on the microwave temperature measuring system with a known radiation source, the linear relationship between the output voltage and the brightness temperature of the object is obtained. Since the metal aluminum plate, antenna, and transmission line will have a non-linear influence on the receiver system, their temperature characteristics and the brightness temperature of the object are used as the inputs of the neural network to obtain a higher accuracy of inversion temperature. The temperature prediction mean square error of a back propagation (BP) neural network is 0.629 °C, and its maximum error is 3.351 °C. This paper innovatively proposed the high-precision PSO-LM-BP temperature inversion algorithm. According to the global search ability of the particle swarm optimization (PSO) algorithm, the initial weight of the network can be determined effectively, and the Levenberg-Marquardt (LM) algorithm makes use of the second derivative information, which has higher convergence accuracy and iteration efficiency. The mean square error of the PSO-LM-BP temperature inversion algorithm is 0.002 °C, and its maximum error is 0.209 °C.

A Rolling Circle-Amplified G-Quadruplex/Hemin DNAzyme for Chemiluminescence Immunoassay of the SARS-CoV-2 Protein.

Sensitive detection of the SARS-CoV-2 protein remains a great research interest in clinical screening and diagnosis owing to the coronavirus epidemic. Here, an ultrasensitive chemiluminescence (CL) imaging strategy was developed through proximity hybridization to trigger the formation of a rolling circle-amplified G-quadruplex/hemin DNAzyme for the detection of the SARS-CoV-2 protein. The target protein was first recognized by a pair of DNA-antibody conjugates, Ab-1 and Ab-2, to form a proximity-ligated complex, Ab-1/SARS-CoV-2/Ab-2, which contained a DNA sequence complemental to block DNA and thus induced a strand displacement reaction to release the primer from a block/primer complex. The released primer then triggered a rolling circle amplification to form abundant DNAzyme units in the presence of hemin, which produced a strong chemiluminescent signal for the detection of the target protein by catalyzing the oxidation of luminol by hydrogen peroxide. The proposed assay showed a detectable concentration range over 5 orders of magnitude with the detection limit down to 6.46 fg/mL. The excellent selectivity, simple procedure, acceptable accuracy, and intrinsic high throughput of the imaging technique for analysis of serum samples demonstrated the potential applicability of the proposed detection method in clinical screening and diagnosis.

Willingness to receive future COVID-19 vaccines following the COVID-19 epidemic in Shanghai, China.

BACKGROUND: There are no pharmacological interventions currently available to prevent the transmission of SARS-CoV-2 or to treat COVID-19. The development of vaccines against COVID-19 is essential to contain the pandemic. we conducted a cross-sectional survey of Shanghai residents to understand residents' willingness to be vaccinated with any future COVID-19 vaccines and take measures to further improve vaccination coverage. METHODS: We conducted a cross-sectional survey using self-administered anonymous questionnaires from 1 July to 8 September 2020. The main outcome was willingness of participants, and any children or older individuals living with them, to receive future COVID-19 vaccines. Logistic regression analyses were used to explore potential factors associated with vaccination willingness. RESULTS: A total of 1071 participants were asked about their willingness to receive future COVID-19 vaccines, for themselves and at least 747 children and 375 older individuals (≥60 years old) living with them. The highest proportion of expected willingness to vaccinate was among participants (88.6%), followed by children (85.3%) and older individuals (84.0%). The main reasons for reluctance to vaccinate among 119 participants were doubts regarding vaccine safety (60.0%) and efficacy (28.8%). Participants with a self-reported history of influenza vaccination were more likely to accept COVID-19 vaccines for themselves [adjusted odds ratio (OR) = 1.83; 95% confidence interval (CI): 1.19-2.82], their children (adjusted OR = 2.08; 95%CI: 1.30-3.33), and older individuals in their household (adjusted OR = 2.12; 95%CI: 1.14-3.99). Participants with older individuals in their families were less willing to vaccinate themselves (adjusted OR = 0.59; 95%CI: 0.40-0.87) and their children (adjusted OR = 0.58; 95%CI: 0.38-0.89). CONCLUSIONS: Participants were more reluctant to accept COVID-19 vaccines for older individuals living with them. The presence of older individuals in the home also affected willingness of participants and their children to be vaccinated.