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DNA ligases are essential enzymes involved in DNA replication and repair processes in all organisms. These enzymes seal DNA breaks by catalyzing the formation of phosphodiester bonds between juxtaposed 5′ phosphate and 3′ hydroxyl termini in double-stranded DNA. In addition to their critical roles in maintaining genomic integrity, DNA ligases have been recently identified as diagnostic biomarkers for several types of cancers and recognized as potential drug targets for the treatment of various diseases. Although DNA ligases are significant in basic research and medical applications, developing strategies for efficiently detecting and precisely quantifying these crucial enzymes is still challenging. Here, we report our design and fabrication of a highly sensitive and specific biosensor in which a stable DNA hairpin is utilized to stimulate the generation of fluorescence signals. This probe is verified to be stable under a wide range of experimental conditions and exhibits promising performance in detecting DNA ligases. We anticipate that this hairpin-based biosensor will significantly benefit the development of new targeting strategies and diagnostic tools for certain diseases. [ABSTRACT FROM AUTHOR]

Magnetic particles are widely used as signal labels in a variety of biological sensing applications, such as molecular detection and related strategies that rely on ligand-receptor binding. In this review, we explore the fundamental concepts involved in designing magnetic particles for biosensing applications and the techniques used to detect them. First, we briefly describe the magnetic properties that are important for bio-sensing applications and highlight the associated key parameters (such as the starting materials, size, functionalization methods, and bio-conjugation strategies). Subsequently, we focus on magnetic sensing applications that utilize several types of magnetic detection techniques: spintronic sensors, nuclear magnetic resonance (NMR) sensors, superconducting quantum interference devices (SQUIDs), sensors based on the atomic magnetometer (AM), and others. From the studies reported, we note that the size of the MPs is one of the most important factors in choosing a sensing technique. [ABSTRACT FROM AUTHOR]

In this study, we describe the development of a cancer biomarker-sensitive nanobiosensor based on localized surface plasmon resonance that enables recognition for proteolytic activity of membrane type 1 matrix metalloproteinase (MT1-MMP) anchored on invasive cancer cells. First of all, we prepared biomarker-detectable substrate based on gold nanorods (GNRs) using nanoparticle adsorption method. The sensitivity of the sensing chip was confirmed using various solvents that have different refractive indexes. Subsequently, MT1-MMP-specific cleavable peptide was conjugated onto the surface of GNRs, and molecular sensing about proteolytic activity was conducted using MT1-MMP and cell lysates. Collectively, we developed a biomarker detectable sensor, which allows for the effective detection of proteolytic activity about MT1-MMP extracted from invasive cancer cells. [ABSTRACT FROM AUTHOR]

Abstract: Fluorescence-based molecular sensing and cellular imaging are commonly carried out with the application of organic dyes. Quantum dots (QDs) are now recognized as better tools because they are brighter, size tunable, and more photostable than dyes. Most of the proposed QD-based biosensing systems involve elements of known toxicity. The present work reports the functionalization of biocompatible InGaP/ZnS core–shell QDs with anti-bovine serum albumin (anti-BSA) to exploit them as fluorescent probes for antigen detection. Successful bioconjugation was characterized with the absorption and emission spectra showing blue shifts of around 40 and 30nm, respectively. Gel electrophoresis and particle size distribution studies further confirmed the mass increment of QDs after their functionalization with anti-BSA. Surface plasmon resonance spectrometry has been used to study the affinity of QD-(anti-BSA) probes for bovine serum albumin (BSA). Photoluminescence quenching of the developed probe is observed in the presence of BSA. [Copyright &y& Elsevier]