A review on corona virus disease 2019 (COVID-19): current progress, clinical features and bioanalytical diagnostic methods

Nanomaterials-based immunosensors for avian influenza virus detection

Avian influenza viruses (AIV) are capable of infecting a considerable proportion of the world's population each year, leading to severe epidemics with high rates of morbidity and mortality. The methods now used to diagnose influenza virus A include the Western blot test (WB), hemagglutination inhibition (HI), and enzyme-linked immunosorbent assays (ELISAs). But because of their labor-intensiveness, lengthy procedures, need for costly equipment, and inexperienced staff, these approaches are considered inappropriate. The present review elucidates the recent advancements in the field of avian influenza detection through the utilization of nanomaterials-based immunosensors between 2014 and 2024. The classification of detection techniques has been taken into account to provide a comprehensive overview of the literature. The review encompasses a detailed illustration of the commonly employed detection mechanisms in immunosensors, namely, colorimetry, fluorescence assay, surface plasmon resonance (SPR), surface-enhanced Raman spectroscopy (SERS), electrochemical detection, quartz crystal microbalance (QCM) piezoelectric, and field-effect transistor (FET). Furthermore, the challenges and future prospects for the immunosensors have been deliberated upon. The present review aims to enhance the understanding of immunosensors-based sensing platforms for virus detection and to stimulate the development of novel immunosensors by providing novel ideas and inspirations. Therefore, the aim of this paper is to provide an updated information about biosensors, as a recent detection technique of influenza with its details regarding the various types of biosensors, which can be used for this review.

Evaluation and comparison of one-step real-time PCR and one-step RT-LAMP methods for detection of SARS-CoV-2

BACKGROUND

There is an increasing disease trend for SARS-COV-2, so need a quick and affordable diagnostic method. It should be highly accurate and save costs compared to other methods. The purpose of this research is to achieve these goals.

METHODS

This study analyzed 342 samples using TaqMan One-Step RT-qPCR and fast One-Step RT-LAMP (Reverse Transcriptase Loop-Mediated Isothermal Amplification). The One-Step LAMP assay was conducted to assess the sensitivity and specificity.

RESULTS

The research reported positive samples using two different methods. In the RT-LAMP method, saliva had 92 positive samples (26.9%) and 250 negative samples (73.09%) and nasopharynx had 94 positive samples (27.4%) and 248 negative samples (72.51%). In the RT-qPCR method, saliva had 86 positive samples (25.1%) and 256 negative samples (74.8%) and nasopharynx had 93 positive samples (27.1%) and 249 negative samples (72.8%). The agreement between the two tests in saliva and nasopharynx samples was 93% and 94% respectively, based on Cohen's kappa coefficient (κ) (P < 0.001). The rate of sensitivity in this technique was reported at a dilution of 1 × 101 and 100% specificity.

CONCLUSIONS

Based on the results of the study the One-Step LAMP assay has multiple advantages. These include simplicity, cost-effectiveness, high sensitivity, and specificity. The One-Step LAMP assay shows promise as a diagnostic tool. It can help manage disease outbreaks, ensure prompt treatment, and safeguard public health by providing rapid, easy-to-use testing.

A sensitive gold nanoflower-based lateral flow assay coupled with gold staining technique for the detection of SARS-CoV-2 antigen

An enhanced lateral flow assay (LFA) is presented for rapid and highly sensitive detection of acute respiratory syndrome coronavirus-2 (SARS-CoV-2) antigens with gold nanoflowers (Au NFs) as signaling markers and gold enhancement to amplify the signal intensities. First, the effect of the morphology of gold nanomaterials on the sensitivity of LFA detection was investigated. The results showed that Au NFs prepared by the seed growth method showed a 5-fold higher detection sensitivity than gold nanoparticles (Au NPs) of the same particle size, which may benefit from the higher extinction coefficient and larger specific surface area of Au NFs. Under the optimized experimental conditions, the Au NFs-based LFA exhibited a detection limit (LOD) of 25 pg mL-1 for N protein using 135 nm Au NFs as the signaling probes. The signal was further amplified by using a gold enhancement strategy, and the LOD for the detection of N protein achieved was 5 pg mL-1. The established LFA also exhibited good repeatability and stability and showed applicability in the diagnosis of SARS-CoV-2 infection.

Insights into the Activation of Unfolded Protein Response Mechanism during Coronavirus Infection

Coronaviruses represent a significant class of viruses that affect both animals and humans. Their replication cycle is strongly associated with the endoplasmic reticulum (ER), which, upon virus invasion, triggers ER stress responses. The activation of the unfolded protein response (UPR) within infected cells is performed from three transmembrane receptors, IRE1, PERK, and ATF6, and results in a reduction in protein production, a boost in the ER's ability to fold proteins properly, and the initiation of ER-associated degradation (ERAD) to remove misfolded or unfolded proteins. However, in cases of prolonged and severe ER stress, the UPR can also instigate apoptotic cell death and inflammation. Herein, we discuss the ER-triggered host responses after coronavirus infection, as well as the pharmaceutical targeting of the UPR as a potential antiviral strategy.

Emerging Trends of Gold Nanostructures for Point-of-Care Biosensor-Based Detection of COVID-19

In 2019, a worldwide pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerged. SARS-CoV-2 is the deadly microorganism responsible for coronavirus disease 2019 (COVID-19), which has caused millions of deaths and irreversible health problems worldwide. To restrict the spread of SARS-CoV-2, accurate detection of COVID-19 is essential for the identification and control of infected cases. Although recent detection technologies such as the real-time polymerase chain reaction delivers an accurate diagnosis of SARS-CoV-2, they require a long processing duration, expensive equipment, and highly skilled personnel. Therefore, a rapid diagnosis with accurate results is indispensable to offer effective disease suppression. Nanotechnology is the backbone of current science and technology developments including nanoparticles (NPs) that can biomimic the corona and develop deep interaction with its proteins because of their identical structures on the nanoscale. Various NPs have been extensively applied in numerous medical applications, including implants, biosensors, drug delivery, and bioimaging. Among them, point-of-care biosensors mediated with gold nanoparticles (GNPSs) have received great attention due to their accurate sensing characteristics, which are widely used in the detection of amino acids, enzymes, DNA, and RNA in samples. GNPS have reconstructed the biomedical application of biosensors because of its outstanding physicochemical characteristics. This review provides an overview of emerging trends in GNP-mediated point-of-care biosensor strategies for diagnosing various mutated forms of human coronaviruses that incorporate different transducers and biomarkers. The review also specifically highlights trends in gold nanobiosensors for coronavirus detection, ranging from the initial COVID-19 outbreak to its subsequent evolution into a pandemic.

Recent advances in application of computer-aided drug design in anti-COVID-19 Virials Drug Discovery

Corona Virus Disease 2019 (COVID-19) is a global pandemic epidemic caused by severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2), which poses a serious threat to human health worldwide and results in significant economic losses. With the continuous emergence of new virus strains, small molecule drugs remain the most effective treatment for COVID-19. The traditional drug development process usually requires several years; however, the development of computer-aided drug design (CADD) offers the opportunity to develop innovative drugs quickly and efficiently. The literature review describes the general process of CADD, the viral proteins that play essential roles in the life cycle of SARS-CoV-2 and can serve as therapeutic targets, and examples of drug screening of viral target proteins by applying CADD methods. Finally, the potential of CADD in COVID-19 therapy, the deficiency, and the possible future development direction are discussed.

Rapid assays of SARS-CoV-2 virus and noble biosensors by nanomaterials

The COVID-19 outbreak caused by SARS-CoV-2 in late 2019 has spread rapidly across the world to form a global epidemic of respiratory infectious diseases. Increased investigations on diagnostic tools are currently implemented to assist rapid identification of the virus because mass and rapid diagnosis might be the best way to prevent the outbreak of the virus. This critical review discusses the detection principles, fabrication techniques, and applications on the rapid detection of SARS-CoV-2 with three categories: rapid nuclear acid augmentation test, rapid immunoassay test and biosensors. Special efforts were put on enhancement of nanomaterials on biosensors for rapid, sensitive, and low-cost diagnostics of SARS-CoV-2 virus. Future developments are suggested regarding potential candidates in hospitals, clinics and laboratories for control and prevention of large-scale epidemic.

Potential Antiviral Effect of Korean Forest Wild Mushrooms against Feline Coronavirus (FCoV)

Coronaviruses (CoV) are among the major viruses that cause common cold in humans. Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is a high-risk human pathogen that derived from bat coronaviruses, although several other animals serve as CoV hosts, contributing to human infection. As the human activity area expanded, viruses previously prevalent only in animals mutated and became threats to humans as well, leading to worldwide epidemics. Therefore, controlling CoV infections in animals is essential to prevent CoV-related human infections. Feline coronavirus (FCoV) could be reportedly used as an alternative model for SARS-CoV-2. Traditionally, mushrooms are not only foods but are also consumed to prevent diseases. Importantly, certain edible and medicinal mushrooms display antibacterial and antiviral effects against respiratory pathogens; therefore, they could be tested as potential coronavirus treatment agents. In this study, we investigated if wild forest mushrooms with various reported physiological activities could exhibit an antiviral activity against CoV, using FCoV as a SARS-CoV-2 model infecting Crandell Rees feline kidney cells. We measured the antiviral activity of 11 wild mushrooms overall and our results demonstrated that Pleurotus ostreatus and Phallus luteus displayed the highest antiviral efficacy of 55.33%, followed by Tricholoma bakamatsutake at 43.77%. Grifola frondosa, Morchella esculenta, and Sarcodon imbricatus exhibited mild efficacy of 29.21%. We also tested Amanita caesareoides, Marasmius siccus, Pachyma hoelen, Phallus rubrovolvata, and Sparassis latifolia but could not detect any antiviral activity in their case. Our study confirms that wild forest mushrooms could be used as potential functional foods or pharmacological materials against coronavirus.

Increase in complicated upper respiratory tract infection in children during the 2022/2023 winter season-a post coronavirus disease 2019 effect?

BACKGROUND

Upper respiratory tract infections usually peak during winter months.

OBJECTIVE

The purpose of this study was to evaluate whether imaging of complicated upper airway infection in children increased during the winter season of 2022/2023.

MATERIALS AND METHODS

In a retrospective study setting, pediatric magnetic resonance imaging (MRI) and computed tomography (CT) scans for evaluation of upper respiratory tract infection performed between October 2022 and April 2023 were analyzed regarding presence of the following complications: mastoiditis, abscess, phlegmon, meningitis, reactive vasculitis, and sinus vein thrombosis. Pathogen detection, surgery, and infection parameters were obtained. Data were compared with MRI and CT scans performed in the same months of the preceding five years, distinguishing between pandemic and pre-pandemic years.

RESULTS

During the 2022/2023 winter season, the number of MRI and CT scans in children with upper airway infections, the complication rate, the rate of detected streptococcal infections, and the rate of surgery increased significantly compared to expectations based on the five prior winter seasons (all P<0.05). During the first complete pandemic winter season in Europe (2020/2021), the number of MRI and CT scans in children with upper airway infection, the complication rate, and the rates of streptococcal detection and surgery decreased significantly compared to expectations based on the pre-pandemic, the second pandemic, and the post-pandemic winter seasons (all P<0.05).

CONCLUSION

After a decline during the first pandemic winter season, there was a marked rebound in complicated upper airway infection in children, with a significant increase in cases during the 2022/2023 winter season compared to the pre-pandemic and pandemic years.

A gene polymorphism at SP-B 1580 site regulates the pulmonary surfactant tension of viral pneumonia through the cellular pyroptosis signaling pathway

BACKGROUND

Viral pneumonias, such as SARS and MERS, have been a recurrent challenge for the public healthcare system. COVID-19 posed an unprecedented global crisis. The primary impact of viral pneumonia is pathologic changes of lung tissue. However, the effect of SP-B site gene polymorphism on alveolar surface tension in viral pneumonia remains unexplored.

OBJECTIVE

To explore the molecular mechanism of how the gene polymorphism at SP-B 1580 site regulates the pulmonary surfactant tension of viral pneumonia through the cellular pyroptosis signaling pathway using an in vivo animal experiment and a clinical trial.

METHODS

We constructed a genetically modified mouse model of viral pneumonia and administered H5N1 influenza virus through intratracheal injection. After 48 hours, the survival rate of each mouse group was evaluated. Lung tissue, blood, and bronchoalveolar lavage fluid samples were collected for histopathologic analysis. Inflammatory factor concentrations were measured using ELISA. The level of apoptosis was determined using TUNEL assay. Changes in the expression of cell death-related factors were assessed using qRT-PCR and protein blotting. Additionally, blood samples from patients with viral pneumonia were analyzed to detect single nucleotide polymorphisms and explore their correlation with disease severity, inflammatory factor levels, and pulmonary surfactant protein expression.

RESULTS

Following H5N1 infection of mice, the model group and hSP-B-C group showed high mortality rates within 24 hours. The survival rates in the blank control group, virus model group, hSP-B-C group, and hSP-B-T group were 100%, 50%, 37.5%, and 75%, respectively. Histologic analysis revealed significant lung tissue damage, congestion, alveolar destruction, and thickened alveolar septa in the model and hSP-B-C groups. However, these pulmonary lesions were significantly alleviated in the hSP-B-T group. Inflammatory factor levels were elevated in the model and hSP-B-C groups but reduced in the hSP-B-T group. TUNEL assay demonstrated a decrease in apoptotic cells in the lungs of the hSP-B-T group. Furthermore, the expression of SP-B and cell death-related proteins was downregulated in all three groups, with the lowest expression observed in the hSP-B-C group. The clinical trial found that patients with severe viral pneumonia exhibited a higher frequency of CC genotype and C allele in, along with increased inflammatory factor levels and decreased SP-B expression compared to those with mild-to-moderate viral pneumonia.

CONCLUSION

SP-B polymorphism at the 1580 site regulates lung surfactant tension through the cell pyroptosis signaling pathway, thus affecting the progression of viral pneumonia.

Fluorescent immunochromatographic test strip for therapeutic drug monitoring of methotrexate with high sensitivity and wide dynamic range

As a front-line chemotherapeutic drug for maintenance and consolidation therapy, methotrexate (MTX) has widely been applied to treat various tumors and some inflammatory diseases. However, because of its severe toxicity ascribed to low selectivity, it is necessary to monitor therapeutic drugs in high-dose MTX therapeutic regimens to ensure treatment safety. In this work, we developed a fluorescent immunochromatographic test strip (FITS) for monitoring MTX by employing time-resolved fluorescent microspheres as signal probes. With a competitive immunoassay mode, the FITS for MTX shows a super-wide dynamic range of 10 pM-10 μM, covering the entire clinical therapeutic concentration range of MTX. Therapeutic drug monitoring of MTX can be achieved within 7 min with high specificity, facilitating the timely rescue of drug poisoning led by high-dose MTX treatment. The method was employed for monitoring MTX in the spiked human serum, urine, and milk, showing acceptable recoveries ranging from 94.0 to 110.0%. The established FITS has been applied to MTX detection in serum obtained from high-dose MTX treatment. The results from FITS and enzyme multiplied immunoassay technique showed no significant difference, suggesting its reliability for usage in real biological samples. The device shows promise in point-of-care therapeutic drug monitoring for resource-limited countries and institutes, which significantly facilitates overcoming the lag time between sampling and results.

Detection of live SARS-CoV-2 virus and its variants by specially designed SERS-active substrates and spectroscopic analyses

A method using label-free surface enhanced Raman spectroscopy (SERS) based on substrate design is provided for an early detection and differentiation of spike glycoprotein mutation sites in live SARS-CoV-2 variants. Two SERS-active substrates, Au nanocavities (Au NCs) and Au NPs on porous ZrO₂ (Au NPs/pZrO₂), were used to identify specific peaks of A.3, Alpha, and Delta variants at different concentrations and demonstrated the ability to provide their SERS spectra with detection limits of 0.1–1.0% (or 10⁴⁻⁵ copies/mL). Variant identification can be achieved by cross-examining reference spectra and analyzing the substrate-analyte relationship between the suitability of the analyte upon the hotspot(s) formed at high concentrations and the effective detection distance at low concentrations. Mutation sites on the S1 chain of the spike glycoprotein for each variant may be related and distinguishable. This method does not require sample preprocessing and therefore allows for fast screening, which is of high value for more comprehensive and specific studies to distinguish upcoming variants.

Bifunctional Au@Pt/Au nanoparticles as electrochemiluminescence signaling probes for SARS-CoV-2 detection

A novel immunosensor based on electrochemiluminescence resonance energy transfer (ECL-RET) for the sensitive determination of N protein of the SARS-CoV-2 coronavirus is described. For this purpose, bifunctional core@shell nanoparticles composed of a Pt-coated Au core and finally decorated with small Au inlays (Au@Pt/Au NPs) have been synthesized to act as ECL acceptor, using [Ru (bpy)₃]²⁺ as ECL donor. These nanoparticles are efficient signaling probes in the immunosensor developed. The proposed ECL-RET immunosensor has a wide linear response to the concentration of N protein of the SARS-CoV-2 coronavirus with a detection limit of 1.27 pg/mL. Moreover, it has a high stability and shows no response to other proteins related to different virus. The immunosensor has achieved the quantification of N protein of the SARS-CoV-2 coronavirus in saliva samples. Results are consistent with those provided by a commercial colorimetric ELISA kit. Therefore, the developed immunosensor provides a feasible and reliable tool for early and effective detection of the virus to protect the population.

Chimeric Hepatitis B core virus-like particles harboring SARS-CoV2 epitope elicit a humoral immune response in mice

BACKGROUND

Virus-like particles are an interesting vector platform for vaccine development. Particularly, Hepatitis B virus core antigen has been used as a promising VLP platform. It is highly expressed in different recombinant expression systems, such as E. coli, and self-assembled in vitro. It effectively improves the immunogenicity of foreign antigenic epitopes on its surface. Various foreign antigens from bacteria, viruses, and protozoa can be genetically inserted into such nanoparticles. The effective immunogenicity due to VLP vaccines has been reported. However, no research has been performed on the SARS-CoV2 vaccine within this unique platform through genetic engineering. Considering the high yield of target proteins, low cost of production, and feasibility of scaling up, E. coli is an outstanding expression platform to develop such vaccines. Therefore, in this investigation, we planned to study and develop a unique HBc VLP-based vaccine against SARS-Cov2 utilizing the E. coli expression system due to its importance.

RESULTS

Insertion of the selected epitope was done into the major immunodominant region (MIR) of truncated (149 residues) hepatitis B core capsid protein. The chimeric protein was constructed in PET28a⁺ and expressed through the bacterial E. coli BL21 expression system. However, the protein was expressed in inclusion body forms and extracted following urea denaturation from the insoluble phase. Following the extraction, the vaccine protein was purified using Ni2 + iminodiacetic acid (IDA) affinity chromatography. SDS-PAGE and western blotting were used to confirm the protein expression. Regarding the denaturation step, the unavoidable refolding process was carried out, so that the chimeric VLP reassembled in native conformation. Based on the transmission electron microscopy (TEM) analysis, the HBC VLP was successfully assembled. Confirming the assembled chimeric VLP, we explored the immunogenic effectivity of the vaccine through mice immunization with two-dose vaccination with and without adjuvant. The utilization of adjuvant was suggested to assess the effect of adjuvant on improving the immune elicitation of chimeric VLP-based vaccine. Immunization analysis based on anti-spike specific IgG antibody showed a significant increase in antibody production in harvested serum from immunized mice with HBc-VLP harboring antigenic epitope compared to HBc-VLP- and PBS-injected mice.

CONCLUSIONS

The results approved the successful production and the effectiveness of the vaccine in terms of humoral IgG antibody production. Therefore, this platform can be considered a promising strategy for developing safe and reasonable vaccines; however, more complementary immunological evaluations are needed.

Relationship between Tai Chi and clinical outcomes in elderly patients with COVID-19: a protocol for systematic review and dose-response meta-analysis

INTRODUCTION

COVID-19 has posed a serious threat to people worldwide, especially the older adults, since its discovery. Tai Chi as a traditional Chinese exercisethat belongs to traditional Chinese medicine has proven its effectiveness against COVID-19. However, no high-quality evidence is found on the dose-response relationships between Tai Chi and clinical outcomes in patients with COVID-19. This study will evaluate and determine the clinical evidence of Tai Chi as a treatment in elderly patients with COVID-19.

METHODS AND ANALYSIS

The following electronic bibliographical databases including PubMed, EMBASE, Web of Science, Cochrane Library, China National Knowledge Infrastructure, VIP Database and Wanfang Database will be screened from their inception date to 30 June 2022. All eligible randomised controlled trials or controlled clinical trials related to Tai Chi for elderly patients with COVID-19 will be included. The primary outcomes are forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC) and FEV1/FVC ratio (FEV1%). The secondary outcomes are the time of main symptoms disappearance, length of hospital stay, serum levels of interleukin (IL)-6, IL-1b and tumour necrosis factor-α, and adverse event rate. Two independent reviewers will select the studies, extract the data, and analyse them on EndNote V.X9.0 and Stata V.12.1. The robust error meta-regression model will be used to establish the dose-response relationships between Tai Chi and clinical outcomes. The heterogeneity and variability will be analysed by I2 and τ2 statistics. Risk of bias, subgroup analysis and sensitivity analysis will also be performed. The quality of evidence will be assessed by the Grading of Recommendations Assessment, Development and Evaluation, and the risk of bias will be evaluated by using the Physiotherapy Evidence Database Scale.

ETHICS AND DISSEMINATION

This study will review published data; thus, obtaining ethical approval and consent is unnecessary. The results will be disseminated through peer-reviewed publications.

PROSPERO REGISTRATION NUMBER

CRD42022327694.

Advances in Biosensing Technologies for Diagnosis of COVID-19

The COVID-19 pandemic has severely impacted normal human life worldwide. Due to its rapid community spread and high mortality statistics, the development of prompt diagnostic tests for a massive number of samples is essential. Currently used traditional methods are often expensive, time-consuming, laboratory-based, and unable to handle a large number of specimens in resource-limited settings. Because of its high contagiousness, efficient identification of SARS-CoV-2 carriers is crucial. As the advantages of adopting biosensors for efficient diagnosis of COVID-19 increase, this narrative review summarizes the recent advances and the respective reasons to consider applying biosensors. Biosensors are the most sensitive, specific, rapid, user-friendly tools having the potential to deliver point-of-care diagnostics beyond traditional standards. This review provides a brief introduction to conventional methods used for COVID-19 diagnosis and summarizes their advantages and disadvantages. It also discusses the pathogenesis of COVID-19, potential diagnostic biomarkers, and rapid diagnosis using biosensor technology. The current advancements in biosensing technologies, from academic research to commercial achievements, have been emphasized in recent publications. We covered a wide range of topics, including biomarker detection, viral genomes, viral proteins, immune responses to infection, and other potential proinflammatory biomolecules. Major challenges and prospects for future application in point-of-care settings are also highlighted.

AuNP-based biosensors for the diagnosis of pathogenic human coronaviruses: COVID-19 pandemic developments

The outbreak rate of human coronaviruses (CoVs) especially highly pathogenic CoVs is increasing alarmingly. Early detection of these viruses allows treatment interventions to be provided more quickly to people at higher risk, as well as helping to identify asymptomatic carriers and isolate them as quickly as possible, thus preventing the disease transmission chain. The current diagnostic methods such as RT-PCR are not ideal due to high cost, low accuracy, low speed, and probability of false results. Therefore, a reliable and accurate method for the detection of CoVs in biofluids can become a front-line tool in order to deal with the spread of these deadly viruses. Currently, the nanomaterial-based sensing devices for detection of human coronaviruses from laboratory diagnosis to point-of-care (PoC) diagnosis are progressing rapidly. Gold nanoparticles (AuNPs) have revolutionized the field of biosensors because of the outstanding optical and electrochemical properties. In this review paper, a detailed overview of AuNP-based biosensing strategies with the varied transducers (electrochemical, optical, etc.) and also different biomarkers (protein antigens and nucleic acids) was presented for the detection of human coronaviruses including SARS-CoV-2, SARS-CoV-1, and MERS-CoV and lowly pathogenic CoVs. The present review highlights the newest trends in the SARS-CoV-2 nanobiosensors from the beginning of the COVID-19 epidemic until 2022. We hope that the presented examples in this review paper convince readers that AuNPs are a suitable platform for the designing of biosensors.

On-bead DNA synthesis triggered by allosteric probe for detection of carcinoembryonic antigen

Sensitive quantification of protein biomarkers is highly desired for clinical diagnosis and treatment. Yet, unlike DNA/RNA which can be greatly amplified by PCR/RT-PCR, the amplification and detection of trace amount of proteins remain a great challenge. Here, we combined allosteric probe (AP) with magnetic bead (MB) for assembling an on-bead DNA synthesis system (named as APMB) to amplify protein signals. The AP is designed and conjugated onto the MB, enabling the protein biomarker to be separated and enriched. Once recognizing the biomarker, the AP alters its conformation to initiate DNA synthesis on beads for primary signal amplification. During the DNA synthesis, biotin-dATPs are incorporated into the newly synthesized DNA strands. Then, the biotin-labeled DNA specifically captures streptavidin (STR)–conjugated horseradish peroxidase (HRP), which is used to catalyze a colorimetric reaction for secondary signal amplification. By using carcinoembryonic antigen (CEA) as a protein model, the APMB can quantify protein biomarkers of as low as 0.01 ng/mL. The response values measured by APMB are linearly related to the protein concentrations in the range 0.05 to 20 ng/mL. Clinical examination demonstrated good practicability of the APMB in quantifying serum protein biomarker. The on-bead DNA synthesis could be exploited to improve protein signal amplification, thus facilitating protein biomarker detection of low abundance for early diagnosis.

Effect Evaluation of Echocardiography on Right Ventricular Function in Patients after the Recovering from Coronavirus Disease 2019

This research was aimed at exploring the changes in right ventricular function in patients after the recovery of coronavirus disease 2019 (COVID-19) under echocardiography and providing a reference for the rehabilitation and treatment of COVID-19 patients. Three echocardiographic follow-up examinations were performed on 40 recovered COVID-19 patients and 40 healthy people. Right ventricular function between patients after COVID-19 rehabilitation and healthy people was compared. The mean values of right ventricular fractional area change (RVFAC), tricuspid annular plane systolic excursion (TAPSE), right ventricular ejection fraction (RVEF), right myocardial performance index (RMPI), and tricuspid annular plane systolic speed (S') were compared between patients after COVID-19 rehabilitation and healthy subjects. The technical parameters of two-dimensional speckle tracking were compared. The results showed that the differences in RVFAC, TAPSE, RVEF, and RMPI between COVID-19 patients and healthy controls were not significant during the three follow-up periods (P > 0.05). At the first follow-up, the S' was 12.78 cm/s in COVID-19 patients and 13.18 cm/s in healthy subjects. At the second follow-up, the S' was 11.98 cm/s in COVID-19 patients and 12.77 cm/s in healthy subjects. At the third follow-up, the S' was 12.79 cm/s in COVID-19 patients and 13.12 cm/s in healthy subjects. There was no significant difference between the two groups (P > 0.05). In addition, there was no significant difference in right ventricular function between COVID-19 patients and healthy controls, and there was no significant difference in cardiovascular symptoms (P > 0.05). In summary, COVID-19 had no substantial effect on right ventricular function and better recovery in patients.