Quantification of cortisol for the medical diagnosis of multiple pregnancy-related diseases

Electrochemical sensors for cortisol detection: Principles, designs, fabrication, and characterisation

Psychological stress is a major factor contributing to health discrepancies among individuals. Sustained exposure to stress triggers signalling pathways in the brain, which leading to the release of stress hormones in the body. Cortisol, a steroid hormone, is a significant biomarker for stress management due to its responsibility in the body's reply to stress. The release of cortisol in bloodstream prepares the body for a "fight or flight" response by increasing heart rate, blood pressure, metabolism, and suppressing the immune system. Detecting cortisol in biological samples is crucial for understanding its role in stress and personalized healthcare. Traditional techniques for cortisol detection have limitations, prompting researchers to explore alternative strategies. Electrochemical sensing has emerged as a reliable method for point-of-care (POC) cortisol detection. This review focuses on the progress made in electrochemical sensors for cortisol detection, covering their design, principle, and electroanalytical methodologies. The analytical performance of these sensors is also analysed and summarized. Despite significant advancements, the development of electrochemical cortisol sensors faces challenges such as biofouling, sample preparation, sensitivity, flexibility, stability, and recognition layer performance. Therefore, the need to develop more sensitive electrodes and materials is emphasized. Finally, we discussed the potential strategies for electrode design and provides examples of sensing approaches. Moreover, the encounters of translating research into real world applications are addressed.

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

Osteoporosis, a bone disease is caused by the deterioration of bone and shows an enhanced risk of bone fracture and decreasing bone mineral density. Unfortunately, the available radiological techniques are expensive, and have disadvantages such as radiation intake, need a specialist to handle the instrument, and so forth. This research is focused to develop a point-of-care system to identify osteocalcin on current-volt sensor, which helps to diagnose the bone metabolism and prognostics. Antiosteocalcin antibody was attached on the electrode through the silane-modified iron material. The antibody-immobilized sensing surface was utilized to identify the level of osteocalcin and the detection limit of 100 pg/ml reached on linear concentrations of 0.01-3000 ng/ml. Calculations were made by triplicates (n = 3; 3δ) on the determination coefficient of y = 0.2637x-0.6012; R² = 0.9319. Further, control proteins failed to bind with immobilized antibody, confirmed by the specific osteocalcin detection. This research is to identify the osteoporosis biomarker and to help determine the conditions with osteoporosis.

Silica nanoparticle-modified microcomb electrode for voltammetry detection of osteopontin with high sensitivity

Osteosarcoma is a commonly occurring bone malignancy, and it is the second most common cause of cancer deaths in adolescents and children. A sensitive silica nanoparticle (Si-NP) modified current-volt sensor was introduced to identify the osteopontin antigen, a well-known biomarker for osteosarcoma. Si-NP was extracted from the rice husk ash and utilized for the surface functionalization on the interdigitated microelectrode sensing surface. Extracted Si-NP has a spherical shape with uniform distribution, and it is confirmed by field emission scanning electron microscopy and field-emission transmission electron microscopy. Si-NP was layered on the electrode surface through a (3-aminopropyl)triethoxysilane amine linker, and the antibody was immobilized on Si-NP through a glutaraldehyde linker. Osteopontin was effectively detected on the antibody-attached surface, and the determination limit was 0.6 ng/mL. The regression was determined as y = 0.9366x - 1.1113 and the R2 value was 0.9331 and the detection limit of osteopontin was 0.6 ng/mL in the range between 0.3 and 5 ng/mL. In addition, control performance with nonimmune antibodies and albumin did not change the current volt, showing the specific osteopontin identification. This research work brings out the easy and cost-effective method to diagnose osteosarcoma and its etiology.

Aptasensing luteinizing hormone to determine gynecological endocrine complications on graphene oxide layered sensor

Luteinizing hormone (LH)/lutropin is an interstitial cell-stimulating hormone playing a predominant role in the reproductive system, and highly correlated with the infertility treatment in both men and women. This research was concentrated to quantify LH level by using interdigitated electrode sensor. To improve the electric current flow, sensing electrode was modified with graphene oxide (GO) and the aptamer probe was attached on GO through biotin-streptavidin linker. Current responses were measured with aptamer-LH interaction at the target concentrations between 7.5 nM and 1 μM and the detection limit of LH was calculated as 60 nM with the determination coefficient (R² ) value, 0.9229 [y = 1.296x - 2.8435] on a linear range from 30 nM to 1 μM. Further, biofouling effect on sensing electrode surface was analyzed with complementary aptamer sequence, control proteins (albumin and globulin). The above GO-aptamer-modified interdigitated electrode sensor helps to quantify LH level and diagnose gynecological endocrinology-related complications.

Biosensors and biomarkers for determining gestational diabetes mellitus and jaundice in children

Gestational diabetes and jaundice are the correlated diseases predominantly found in mother and newborn child. Jaundice is a neonatal complication with an increased risk when mother has gestational diabetes. Mothers with diabetes at an early stage of gestational age are at higher risk for hyperbilirubinemia (jaundice) and hypoglycemia. So, it is mandatory to monitor the condition of diabetes and jaundice during the pregnancy period for a healthy child and safest delivery. On the other hand, nanotechnology has displayed a rapid advancement that can be implemented to overcome these issues. The development of high-performance diagnosis using appropriate biomarkers provides their efficacy in the detection gestational diabetes and jaundice. This review covers the aspects from a fast-developing field to generate nanosensors in the nanosized dimensions for the applications to overcome these complications by coupling diagnostics with biomarkers. Further, the serum-based biomarkers have been discussed for these inborn complications and also the diagnosis with the current trend.

Longitudinal Zeolite-Iron Oxide Nanocomposite Deposited Capacitance Biosensor for Interleukin-3 in Sepsis Detection

Sepsis is an extreme condition involving a physical response to severe microbial infection and causes fatal and life-threatening issues. Sepsis generates during the chemicals release with the immune system into the bloodstream for fighting against an infection, which causes the inflammation and leads to the medical emergency. A complexed longitudinal zeolite and iron oxide nanocomposite was extracted from coal mine fly ash and utilized to improve the surface characteristics of the capacitance biosensor to identify sepsis attacks. Anti-interleukin-3 (anti-IL-3) antibody was attached to the zeolite- and iron oxide-complexed capacitance electrode surface through an amine linker to interact with the sepsis biomarker IL-3. The morphological and chemical components of the nanocomplex were investigated by FESEM, FETEM, and EDX analyses. At approximately 30 nm, the longitudinal zeolite and iron oxide nanocomposite aided in attaining the limit of IL-3 detection of 3 pg/mL on the linear curve, with a regression coefficient (R2) of 0.9673 [y = 1.638x - 1.1847]. A lower detection limit was achieved in the dose-dependent range (3-100 pg/mL) due to the higher amount of antibody immobilization on the sensing surface due to the nanomaterials and the improved surface current. Furthermore, control experiments with relevant biomolecules did not show capacitance changes, and spiked IL-3 in human serum increased capacitance, indicating the specific and selective detection of IL-3. This study identifies and quantifies IL-3 via potentially useful methods and helps in diagnosing sepsis attack.

Colorimetric identification of miRNA-195 sequence for diagnosing osteosarcoma

Improving biosensing performance is mandatory for biomolecular recognition and disease identification. Gold nanoparticle (GNP)-based colorimetric assay is the easy and cost-effective identification method by a naked eye detection. In this research, osteosarcoma biomarker (miRNA-195) was identified by citrate-capped GNP-colorimetric assay. As salt-induced aggregation was used to observe the color changes of GNP, sodium chloride (NaCl) and capture DNA were optimized as 50 mM and ∼20 pmol, respectively. The capture DNA only on GNP could not stabilize under high NaCl, and the color of GNP turned into purple. At the same time, when capture DNA was hybridized with target, the condition can stabilize the GNP under higher NaCl, which retains the GNP color as red. This simple assay reaches the limit of detection of target miRNA-195 as ∼40 fmol. Control experiments with noncomplementary DNA turned the solution into purple, indicating the specific detection of target. The mixture of target in diluted serum retains the color of the GNP solution to be red, indicating the selective detection of target DNA. This simple assay helps to quantify the level of miRNA-195 target DNA and to diagnose the osteosarcoma.

Current strategies with sensing technologies to eliminate stress cardiomyopathy

Stress cardiomyopathy refers weakening of heart muscle due to the continuous stress. Generally, the severe status of stress cardiomyopathy has been revealed after damaging the muscles and measured by the physical changes in the heart system. To overcome this issue, biosensor can be used, which could eliminate the late identification stress cardiomyopathy. With biosensors, different stress markers such as epinephrine, dopamine, catecholamine, α-amylase, norepinephrine, serotonin and cortisol have been identified by a wide range of developments. These biosensors are available from laboratory to industry at the ranges of nano to macrodevices. To merge with the identification of stress cardiomyopathy, the above strategies might be utilized properly and can aid to reduce the stress-related problems. This overview gleaned the currently available biosensing methods and the associated biomarkers at various stages of the developments and implementations of stress cardiomyopathy.

An interdigitated aptasensor to detect interleukin-6 for diagnosing rheumatoid arthritis in serum

Rheumatoid arthritis (RA) is an autoimmune disorder causing chronic inflammation in the small joints of the articular bone and destruction of articular cartilage. RA causes stiffness, pain, joint destruction, substantial comorbidity, and functional disability. Early-stage diagnosis of RA can help in the treatment of the disease and expand the patient life span. Interleukins are a group of inflammatory cytokines; in particular, an abundance of interleukin-6 (IL-6) was found in the synovial fluid and serum. In RA patients, the levels of IL-6 have been found to be correlated with the disease, and this work focused on detecting IL-6 by its aptamer with the help of a biotin-streptavidin strategy on an interdigitated electrode. A sensitivity of 1 fM (0.021 pg/mL) and a limit of detection of 10 fM (0.21 pg/mL) were found by a linear regression [y = 0.6413x - 0.6249; R² = 0.952] of the linear range from 1 fM to 100 pM. This method enhanced the immobilization of higher aptamer molecules for recognizing RA in serum-containing samples and is applicable to other diseases.

Sensitive determination of NT-proBNP for diagnosing abdominal aortic aneurysms incidence on interdigitated electrode sensor

Abdominal aortic aneurysm (AAA) is a vascular disease found to have progressive growth in the area of aorta. Rupturing of aorta causes excessive bleeding that leads to health-related issues, which can be fatal sometimes. Therefore, it becomes important to make early diagnosis of AAA and its condition and start immediate treatment. Blood-based biomarker helps to diagnose AAA and to monitor the condition after AAA surgery. N-terminal pro-B-type natriuretic peptide (NT-proBNP) is a hormone produced in the heart in small quantities and increased when the heart needs to work harder. NT-proBNP was proved to be strongly linked with AAA incidence. Moreover, quantifying the level of NT-proBNP helps to determine the risk factors on cardiovascular system after the surgery. This work is quantifying the NT-proBNP on interdigitated electrode sensor by using NT-proBNP binding aptamer. The detection limit of NT-proBNP was calculated as 1 pg/mL on a linear regression curve [y = 0.2148x + 0.8849; R² = 0.9049]. The linear range with dose-dependent analysis was from 0.01 until 100 ng/mL. Moreover, the control experiment with complementary aptamer sequence did not show the current signal, specifying the detection of NT-proBNP. This research benefits to identify the heart condition of patient after the removal of AAA.

DNA-RNA complementation on silicon wafer for thyroid cancer determination

One of the current issues with thyroid tumor is early diagnosis as it makes the higher possibility of curing. This research was focused to detect and quantify the level of specific target sequence complementation of miR-222 with capture DNA sequence on interdigitated electrode (IDE) sensor. The aluminum electrode with the gap and finger sizes of 10 µm was fabricated on silicon wafer, further the surface was amine-functionalized for accommodating carboxylated-DNA probe. With DNA-target RNA complementation, the detection limit was attained to be 1 fM as estimated by a linear regression analysis [y = 1.5325x - 2.1171 R² = 0.9065] and the sensitivity was at the similar level. Current responses were higher by increasing the target RNA sequence concentrations. Control experiments with mismatched/noncomplementary sequences were failed to complement the capture DNA sequence immobilized on IDE, indicating the specific target validation. This research helps diagnosing and identifying the progression with thyroid tumor and miRNA being a potential "marker" in atypia diagnosis.