Gold-silane complexed antibody immobilization on polystyrene ELISA surface for enhanced determination of matrix Metalloproteinase-9

Sensitive osteoarthritis sensing by salt-induced aggregation and dispersion of gold nanoparticles

Osteoarthritis occurs in any joints, and identification in its earlier stages helps to treat the disease and increase the recovery rate. The radiography method and imaging techniques are traditionally used to identify osteoarthritis. But these methods are expensive, and with the complicated steps. Researchers are working toward developing a highly sensitive biosensor in identifying the osteoarthritis biomarker. This research was focused on developing a C-terminal telopeptide of type II collagen (CTX-II) colorimetric sensor with gold nanoparticle (AuNP) for diagnosing osteoarthritis. Anti-CTX-II was conjugated with AuNP and then added with CTX-II and sodium chloride for the color change. In the presence of CTX-II, antibody releases from AuNP then binds with CTX-II, and the color of AuNP changed to purple. Without the CTX-II, AuNP remains its red color (dispersed). This easier colorimetric assay detected the CTX-II as low as 2 ng/mL on linear regression [y = 0.0131x - 0.0051; R2 = 0.9205]. Furthermore, control performances with the relevant proteins osteopontin, IL-6, and nonimmune antibody failed to change the color confirming the specific identification of CTX-II.

Evaluating glioma-associated microRNA by complementation on a biological nanosensor

Glioma is a tumor in the brain and spinal cord originating in the glial cells that surround the nerve cells. Among several microRNAs reported, miRNA-363 is associated with human glioma. Based on miRNA-363 levels, the development and progression of glioma can be monitored. The current study used an interdigitated electrode sensor to monitor microRNA-363 levels, which indeed reflects the severity of glioma. The interdigitated electrode was generated using a photolithography technique followed by surface chemical modification carried out to insert miRNA-363 complementary oligo as the probe complexed with gold nanoparticles. The proposed sensor works based on the dipole moment between two electrodes, and when molecular immobilization or interaction occurs, the response by the signal output changes. The changes in the target microRNA-363 sequence were standardized to identify glioma. The limit of detection of miRNA-363 was 10 fM with an R² value of 0.996 on the linear coefficient regression ranges between 1 fM and 100 pM. Furthermore, unrelated sequences failed to increase the response of the current with the complementary probe, indicating specific miRNA-363 detection on interdigitated electrode. This study demonstrates the platform to be used for determining the presence of microRNA-363 in glioma and as the basis for other biomarker analyses. This article is protected by copyright. All rights reserved.

Current-Volt Biosensing "Cystatin C" on Carbon Nanowired Interdigitated Electrode Surface: A Clinical Marker Analysis for Bulged Aorta

A carbon nanowire-modified surface with interdigitated electrode (IDE) sensing system was introduced to identify abdominal aortic aneurysm biomarker "papain," also known as cysteine protease, used as the capture probe to identify Cystatin C. Papain was immobilized through the covalent integration of amine group on papain and the carboxyl group with carbon nanowire. This papain-modified electrode surface was utilized to detect the different concentrations of Cystatin C (100 pg/mL to 3.2 ng/mL). The interaction between papain and Cystatin C was monitored using a picoammeter, and the response curves were compared. With increasing Cystatin C concentrations, the total current levels were gradually increased with a linear range from 200 pg/mL to 3.2 ng/mL, and the current differences were plotted and the detection limit of Cystatin C was calculated as 200 pg/mL. The averaging of three independent experiments (n = 3) was made with 3δ estimation, and the determination coefficient was y = 1.8477 × 0.7303 and R ² = 0.9878. Furthermore, control experiments with creatinine and gliadin failed to bind the immobilized papain, indicating the specific detection of Cystatin C.

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.

Biomolecular assembly on interdigitated electrode nanosensor for selective detection of insulin-like growth factor-1

This research is focussed to quantify IGF1 by electroanalytical analysis on InterDigitated electrode surface and characterized by the microscopic observations. For the detection, antibody and aptamer were used to analyze the level of IGF1. The sandwich pattern (aptamer-IGF1-antibody) was designed on the chemically modified IDE surface and reached the limit of detection to 10 fM with 100 folds enhancement in the sensitivity. Different control experiments (absence of IGF1, binding with IGF2 and with non-complementary aptamer) were failed to show the current changes, discriminated the specific detection. A good detection strategy is to complement the currently following imaging systems for AAA.

Identification of osteosarcoma by microRNA-coupled nuclease digestion on interdigitated electrode sensor

Osteosarcoma is a type of tumor originating from the bone cells, most often from long bones. Children and adolescents are mainly affected by osteosarcoma. Identifying the condition with osteosarcoma is mandatory to provide proper treatment to the affected patients. This research work has introduced an identification of an osteosarcoma biomarker "miRNA-21" on the interdigitated electrochemical sensor by nuclease digestion. The target RNA sequence of miRNA-21 was hybridized to the capture DNA and placed on the sensing electrode surface with the aid of the biotin-streptavidin interaction. The unhybridized immobilized single-standard capture DNA was digested by S1-nuclease. The current response of the digestion level was considered as the duplex formation between the target and capture DNA. Using this technique, the detection limit of the target was reached to 1 fM and a similar response of current was noted with the target RNA-spiked human serum, indicating the selective identification of target RNA. Further, single mismatched, triple mismatched, and random miRNA sequences (miRNA-195) failed to interact with the immobilized capture DNA, representing the specific identification of target RNA. This nuclease digestion technique with miRNA-21 identification helps in detecting osteosarcoma and related issues.

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.

Sensitive silica-alumina modified capacitive non-Faradaic glucose sensor for gestational diabetes

A highly sensitive silica-alumina (Si-Al)-modified capacitive non-Faradaic glucose biosensor was introduced to monitor gestational diabetes. Glucose oxidase (GOx) was attached to the Si-Al electrode surface as the probe through amine-modification followed by glutaraldehyde premixed GOx as aldehyde-amine chemistry. This Si-Al (∼50 nm) modified electrode surface has increased the current flow upon binding of GOx with glucose. Capacitance values were increased by increasing the glucose concentrations. A mean capacitance value was plotted and the detection limit was found as 0.03 mg/mL with the regression coefficient value, R² = 0.9782 [y = 0.8391x + 1.338] on the linear range between 0.03 and 1 mg/mL. Further, a biofouling experiment with fructose and galactose did not increase the capacitance, indicating the specific glucose detection. This Si-Al-modified capacitance sensor detects a lower level of glucose presence and helps in monitoring gestational diabetes.