Digital Melting Curve Analysis for Multiplex Quantification of Nucleic Acids on Droplet Digital PCR.

We present a cost-effective and simple multiplex nucleic acid quantification method using droplet digital PCR (ddPCR) with digital melting curve analysis (MCA). This approach eliminates the need for complex fluorescent probe design, reducing both costs and dependence on fluorescence channels. We developed a convolutional neighborhood search algorithm to correct droplet displacement during heating, ensuring precise tracking and accurate extraction of melting curves.

Causal impact of DNA methylation on refracture in elderly individuals with osteoporosis - a prospective cohort study.

Background: Osteoporotic vertebral compression fractures (OVCF) in the elderly increase refracture risk post-surgery, leading to higher mortality rates. Genome-wide association studies (GWAS) have identified susceptibility genes for osteoporosis, but the phenotypic variance explained by these genes has been limited, indicating the need to explore additional causal factors. Epigenetic modifications, such as DNA methylation, may influence osteoporosis and refracture risk.

Gravity-driven flow control in a fully integrated microfluidic cartridge for molecular point-of-care testing.

Molecular point-of-care testing (POCT) system is crucial for the timely prevention and control of infectious diseases. We recently proposed a gravity-driven microfluidic cartridge for molecular POCT detection, without the need for external sources or actuators, demonstrating the advantages in terms of the reduced cartridge size and low development costs. How to achieve precise control of liquid flow behavior is challenging for the gravity-driven cartridge.

A sample-to-answer, quantitative real-time PCR system with low-cost, gravity-driven microfluidic cartridge for rapid detection of SARS-CoV-2, influenza A/B, and human papillomavirus 16/18.

The pandemic of coronavirus disease 2019 (COVID-19), due to the novel coronavirus (SARS-CoV-2), has created an unprecedented threat to the global health system, especially in resource-limited areas. This challenge shines a spotlight on the urgent need for a point-of-care (POC) quantitative real-time PCR (qPCR) test for sensitive and rapid diagnosis of viral infections. In a POC system, a closed, single-use, microfluidic cartridge is commonly utilized for integration of nucleic acid preparation, PCR amplification and florescence detection.

Multiple chemiluminescence immunoassay detection of the concentration ratio of glycosylated hemoglobin A1c to total hemoglobin in whole blood samples.

The concentration ratio of glycosylated hemoglobin A1c (HbA1c) to total hemoglobin (Hb) has long been used to accurately determine stagewise diabetes because this parameter represents a reliable and accurate biomarker of mean 90-day blood glucose values. In this paper, we report a time-resolved chemiluminescence assay that can detect both Hb and HbA1c. For the determination of Hb, the interaction of heme in Hb with HO in NaOH solution was performed to generate a chemiluminescence peak.

AutoCell Systematic Evolution of Ligands by Exponential Enrichment: The Software Designed and Developed for the Automated Screening System of Nucleic Acid Aptamers.

Aptamers are a new kind of nano-probes for bioassays and drug delivery, etc. In this paper, software has been developed as an automatic control center for the automated aptamer selecting system which realized the high integration of aptamer selection, data acquisition and processing. This software, applied in windows system, is developed by C# with the Microsoft Visual Studio 2015 integrated developing environment and the database used in this software is implemented using open source relational database MYSQL.

Molecular dynamics discrimination of the conformational states of calmodulin through solid-state nanopores.

As a type of biological macromolecule, the conformation of proteins dynamically changes in a solution, which often results in a change in their function. However, traditional biological assays have significant drawbacks in detecting the conformation properties of proteins. Alternatively, nanopores have potential advantages in this area, which can detect protein in high throughput and without labelling.

Mechanical Gripper Design and Force Analysis of Microplates for Automated High-Throughput Nucleic Acid Detection System.

In the automated high-throughput nucleic acid detection system, we need to grip and transfer consumables frequently when carrying out multichannel nucleic acid detection. In order to ensure the efficiency of experiments and solve problems of the deflection and drop when transferring microplates, we design a self-locking mechanical gripper which consists of a rotary positioning module and a gripping module. The absolute position encoder fixed on the top of the stepper motor can collect the position data of the mechanical gripper in real time and send them to the master control board based on STM32 for processing, which ensures the accuracy of the movement of the mechanical gripper.

Design and Implementation of a High-Throughput Vibrating Module for Nucleic Acid Detection System.

The high-throughput nucleic acid detection system provides a good solution for detecting nucleic acids more safely, rapidly and accurately, which greatly improves the detection efficiency. Highthroughput nucleic acid detection mainly includes three steps: signal acquisition, signal amplification and signal processing. Therefore, obtaining the purified nucleic acid is the primary task of the nucleic acid detection, and the quality of the nucleic acid has a significant impact on results.

Design and Implementation of High-Throughput Magnetic Separation Module for Automated Nucleic Acid Detection System Based on Magnetic Nano-Beads.

With the higher and higher application level of medical technology, more and more genetic diseases have been diagnosed. Nucleic acid, as an important genetic material, has been found to have important functions in the storage and transmission of the genetic information in the replication and synthesis of proteins. As the first step in nucleic acid detection experiments, nucleic acid extraction performance is associated with the purity of target nucleic acid samples, which is very important for the downstream steps.

One-Step Synthesis of DNA Templated Water-Soluble Au-Ag Bimetallic Nanoclusters for Ratiometric Fluorescence Detection of DNA.

DNA strands have been used as templates to form different sized silver nanoclusters. Although DNA templated silver nanoclusters (NCs) probes which show outstanding fluorescence properties have been widely applied in chemical sensing and cellular imaging, synthesis of DNA template Au-Ag bimetallic nanoclusters remains a challenge. A facile one-step synthesis method was thus developed in this study to form Au-Ag NCs using C4-ATAT-C4 as template.

Environmental effect on surface immobilized biological molecules.

Our recent sum frequency generation (SFG) vibrational spectroscopic experiment ( J. Phys. Chem.

Molecular structures of C- and N-terminus cysteine modified cecropin P1 chemically immobilized onto maleimide-terminated self-assembled monolayers investigated by molecular dynamics simulation.

Biosensors using peptides or proteins chemically immobilized on surfaces have many advantages such as better sensitivity, improved stability, and longer shelf life compared to those prepared using physically adsorbed biomolecules. Chemical immobilization can better control the interfacial conformation and orientation of peptides and proteins, leading to better activity of these biomolecules. In this research, molecular dynamics (MD) simulations were employed to systematically investigate the structure and dynamics of surface-tethered antimicrobial peptide cecropin P1 (CP1) modified with a cysteine residue at the C- (CP1c) or N-terminus (cCP1).

Different interfacial behaviors of peptides chemically immobilized on surfaces with different linker lengths and via different termini.

Molecular structures such as conformation and orientation are crucial in determining the activity of peptides immobilized to solid supports. In this study, sum frequency generation (SFG) vibrational spectroscopy was applied to investigate such structures of peptides immobilized on self-assembled monolayers (SAMs). Here cysteine-modified antimicrobial peptide cecropin P1 (CP1) was chemically immobilized onto SAM with a maleimide terminal group.

PEGylated reduced graphene oxide as a superior ssRNA delivery system.

Single stranded ribonucleic acid (ssRNA) acts as a probe, antisense (AS), miRNA analog and inhibitor, and is promising for gene therapy and molecular diagnosis. However, free ssRNA exhibits poor cellular uptake due to its negative charges, and enzyme instability, which have largely limited the practical applications of ssRNA in biomedicine. To address these issues, we have developed a PEGylated reduced graphene oxide (PEG-RGO) nanovector for efficient delivery of ssRNA.

Molecular dynamics simulations of end-tethered single-stranded DNA probes on a silica surface.

The structure of DNA molecules tethered to surfaces may significantly affect the efficiency of hybridization on the DNA microarray. Understanding the structure of single-stranded DNA (ssDNA) tethered to surfaces is critical for applying the molecular recognition function of DNA microarrays. Although a number of experimental methods have been applied to determine the structure of the DNA probe on surfaces, they can not provide enough information on the dynamical behavior of the ssDNAs on surfaces.

Preparation of SiO2/(PMMA/Fe3O4) from monolayer linolenic acid modified Fe3O4 nanoparticles via miniemulsion polymerization.

SiO2/(PMMA/Fe3O4) composite particles were prepared from linolenic acid (LA) instead of oleic acid (OA) modified Fe3O4 nanoparticles by miniemulsion polymerization. LA has three unsaturated double bonds with which it can polymerizate more easily than OA. And coating Fe3O4 with polymethyl methacrylate (PMMA) polymer beforehand can prevent magnetic nanoparticles from the aggregation that usually comes from the increasing of ionic strength during the hydrolyzation of tetraethoxysilane (TEOS) by the steric hindrance.

Effect of single central base pair mismatch on the conformation and stability of surface immobilized DNA: molecular dynamics studies.

We combine molecular dynamics simulations and relative free energy calculation to investigate how single central base mismatch influence the conformation and stability of surface immobilized DNA. For comparison purpose, molecular dynamics simulations have been performed on a central mismatched duplex and the corresponding perfectly matched duplex, respectively. Simulations have been conducted with the generalized Born model.