Identifying mineral decrement with bone injury by quantifying osteocalcin on current-volt sensor

Roles of osteocalcin in the central nervous system

BACKGROUND

Bone-derived protein osteocalcin, which has beneficial effects on brain function, may be a future research direction for neurological disorders. A growing body of evidence suggests a link between osteocalcin and neurological disorders, but the exact relationship is contradictory and unclear.

SCOPE OF REVIEW

The aim of this review is to summarize the current research on the interaction between osteocalcin and the central nervous system and to propose some speculative future research directions.

MAJOR CONCLUSIONS

In the normal central nervous system, osteocalcin is involved in neuronal structure, neuroprotection, and the regulation of cognition and anxiety. Studies on osteocalcin-related abnormalities in the central nervous system are divided into animal model studies and human studies, depending on the subject. In humans, the link between osteocalcin and brain function is inconsistent. These conflicting data may be due to methodological inconsistencies. By reviewing the related literature on osteocalcin, some comorbidities of the bone and nervous system and future research directions related to osteocalcin are proposed.

Recent development on nanomaterial-based biosensors for identifying thyroid tumor biomarkers

The incidence of thyroid tumors has been increasing yearly over the past decade, making it the fourth highest tumor in women. This places various biological burdens on those affected. Currently, thyroid tumors are primarily diagnosed using percutaneous fine needle aspiration and ultrasound. However, these methods are complex, expensive, and less accurate, and they may fail to detect some thyroid nodules. As an alternative, researchers are focusing on blood-based biomarkers in addition to the traditional diagnostic methods, assisted predominantly by nanomaterials. Early identification of thyroid cancer is crucial as it is highly treatable. Various sensing systems have been developed using nanomaterial-mediated approaches to enhance the detection system. Nanomaterials are effectively applied in biosensors for surface functionalization and are conjugated with biomolecules to improve the interaction with the target analyte. This review discusses nanomaterial-assisted thyroid tumor detection, with a special focus on nanomaterial-based biosensors.

High-sensitivity immunoassay on interdigitated electrode to detect osteoporosis biological marker

Osteoporosis is with porous bones, which refers to a decrease in the bone mineral density and weakens the bones to become brittle. Osteoporosis often progresses without any pain or symptoms until the bone fractures. Monitoring the condition of bone regularly helps to identify the bone that weakens at its earlier stages. In general, radiological techniques have been used to measure bone mineral density, are expensive, and the procedures are complicated. Therefore, researchers are focusing on the alternative method of biomarker quantification to identify bone mineral density. This research work was focused on quantifying the osteoporosis biomarker of C-terminal telopeptide of type I collagen (CTX-I) on an interdigitated electrode (IDE) sensor. Gold nanomaterial-modified anti-CTX-I antibody was attached to silica nanomaterial-decorated IDE and then identified by CTX-I interaction. Higher immobilization of antibodies was recorded on diamond-modified IDE through gold nanoparticles, and detected CTX-I as low as 0.5 pg/mL [y = 1.5507x - 0.9043 R2 = 0.9715], determined on a linear curve at the range 0.5-3.5 ng/mL. Further, specific identification of CTX-I was confirmed by control performances with osteopontin, IL-6, and anti-IgG antibody.

Simple immunosensor for ultrasensitive electrochemical determination of biomarker of the bone metabolism in human serum

Ultrasensitive and selective determination of biomarkers of the bone metabolism in serum is crucial for early screening, timely treatment, and monitoring of the curative effect of osteoporosis, which is a silent disease with serious health threats. Immunoassay with a simple sensing interface and ultrahigh sensitivity is highly desirable. Herein, a simple electrochemical immunosensor is demonstrated based on gold nanoparticles (AuNPs) electrodeposited on chitosan-reduced graphene oxide (CS-G) composite modified electrode, which can achieve sensitive determination of the important biomarker of bone metabolism, bone gamma-carboxyglutamate protein (BGP). To overcome the agglomeration of graphene and introduce a biocompatible matrix with functional amino groups, CS-G is prepared and modified on the supporting glassy carbon electrode (GCE). Then, AuNPs are electrodeposited on CS-G through their interaction between amine groups of CS. The immobilized AuNPs provide numerous binding sites to immobilize anti-BGP antibodies (Ab_BGP). The specific recognition between BGP and Ab_BGP results in a reduction in the mass transfer of the electrochemical probe (Fe(CN)₆^3-/4-) in solution, leading to a reduced electrochemical signal. Based on this mechanism, fast and ultrasensitive electrochemical detection of BGP is achieved when the concentration of BGP ranges from 100 ag ml⁻¹ to 10 μg mL⁻¹ with a limit of detection (LOD) of 20 ag ml⁻¹ (S/N = 3). The determination of BGP in human serum is also realized with high reliability.