An IoT-based aptasensor biochip for the diagnosis of periodontal disease.

Severe periodontitis affects nearly 1 billion individuals worldwide, highlighting the need for early diagnosis. Here, an integrated system consisting of a microfluidic chip and a portable point-of-care (POC) diagnostic device is developed using a polymethyl methacrylate (PMMA) chip fabrication and a three-dimensional printing technique, which is automatically controlled by a custom-designed smartphone application to routinely assess the presence of a specific periodontitis biomarker, odontogenic ameloblast-associated protein (ODAM). A sandwich-type fluorescence aptasensor is developed on a microfluidic chip, utilizing aptamer pair (MB@OD64 and OD35@FAM) selectively binding to target ODAM. Then this microfluidic chip is integrated into an automated Internet of Things (IoT)-based POC device, where fluorescence intensity, as a signal, from the secondary aptamer binding to ODAM in a sandwich-type binding reaction on the microfluidic chip is measured by a complementary metal oxide semiconductor (CMOS) camera with a 488 nm light-emitting diode (LED) excitation source. Obtained signals are processed by a microprocessor and visualized on a wirelessly connected smartphone application. This integrated biosensor system allows the rapid and accurate detection of ODAM within 30 min with a remarkable limit of detection (LOD) of 0.011 nM under buffer conditions. Clinical application is demonstrated by successfully distinguishing between low-risk and high-risk individuals with 100 % specificity. A strong potential in the translation of this fluorescence-based microfluidic aptasensor integrated with an IoT-based POC system is expected to be employed for non-invasive, on-site, rapid, and accurate ODAM detection, facilitating periodontitis diagnosis.

Biosensors for healthcare: current and future perspectives.

Biosensors are utilized in several different fields, including medicine, food, and the environment; in this review, we examine recent developments in biosensors for healthcare. These involve three distinct types of biosensor: biosensors for in vitro diagnosis with blood, saliva, or urine samples; continuous monitoring biosensors (CMBs); and wearable biosensors. Biosensors for in vitro diagnosis have seen a significant expansion recently, with newly reported clustered regularly interspaced short palindromic repeats (CRISPR)/Cas methodologies and improvements to many established integrated biosensor devices, including lateral flow assays (LFAs) and microfluidic/electrochemical paper-based analytical devices (µPADs/ePADs). We conclude with a discussion of two novel groups of biosensors that have drawn great attention recently, continuous monitoring and wearable biosensors, as well as with perspectives on the commercialization and future of biosensors.

A new cognate aptamer pair-based sandwich-type electrochemical biosensor for sensitive detection of Staphylococcus aureus.

A pair of aptamers for Staphylococcus aureus (S. aureus) is immensely needed for developing sandwich-type signal-on electrochemical aptasensors. In this study, we have successfully developed a cognate pair of aptamers that bind to S. aureus simultaneously, among many aptamer candidates screened out after a total of ten rounds of bacterial cell-based systemic evolution of ligands by exponential enrichment (SELEX). The obtained aptamer candidates have been estimated by using flow cytometry and confocal microscope, to evaluate their binding affinity and specificity to the target cells. The screening for sandwich-type binding of cognate pair of aptamers with S. aureus was conducted by enzyme-based colorimetric assay and confirmed by circular dichroism (CD), two-color fluorescence imaging analysis, additionally. The cognate pair of two aptamers, named SA37 and SA81, showed very good affinity and specificity to S. aureus with their dissociation constants (Kd) of 16.5 ± 3.4 nM and 14.47 ± 8.18 nM, respectively. These newly discovered cognate pair of aptamers have been very successfully implemented to develop a sandwich-type signal-on electrochemical biosensor with the limit of detection (LOD) of 39 CFUs and 414 CFUs in buffer and spiked tap water samples, respectively. This study showed that this cognate pair of aptamers-based detection of S. aureus enables simple, rapid, and robust biosensors for food safety management.