Redox-Modified Nanostructured Electrochemical Surfaces for Continuous Glucose Monitoring in Complex Biological Fluids.

Continuous glucose monitoring is valuable for people with diabetes but faces limitations due to enzyme-electrode interactions and biofouling from biological samples that reduce sensor sensitivity and the monitoring performance. We created an enzyme-based electrochemical system with a unique nanocomposite coating that incorporates the redox molecule, aminoferrocene (NH2-Fc). This coating enhances stability via electroactivity and reduces nonspecific binding, as demonstrated through cyclic voltammetry. Our approach enables real-time glucose detection via chronoamperometry with a calculated linear range of 0.5 to 20 mM and a 1 mM detection limit. Validated with plasma and saliva, this platform shows promise for robust metabolite detection in clinical and research contexts. This versatile platform can be applied to accurately monitor a wide range of metabolites in various biological matrices, improving patient outcomes.

The Anatomy of a Nonfaradaic Electrochemical Biosensor.

Point-of-care (POC) testing has revolutionized diagnostic healthcare, bringing medical results directly and immediately to the patient. With faster diagnostics, more immediate clinical management decisions can be made. POC tests most often use a dipstick or swab format to detect the presence of a pathogen, disease, or other relevant biomarker. In these formats, the POC tests eliminate the need for complex lab equipment and trained personnel to collect, process, and analyze sample data for simple diagnostics. However, these tests cannot satisfy all clinical needs, because accurate quantitative results are needed. The present study serves as a template for designing a nonfaradaic electrochemical biosensor toward quantitative POC diagnostics. We focus on investigating the most important parameters when constructing a nonfaradaic biosensor through both mathematical modeling and electrochemical measurements. Furthermore, we demonstrate quantitative affinity biosensing of a model protein toward developing a POC device.

Ultrasensitive nanostructure sensor arrays on flexible substrates for multiplexed and simultaneous electrochemical detection of a panel of cardiac biomarkers.

Multiplexed detection of protein biomarkers offers new opportunities for early diagnosis and efficient treatment of complex diseases. Cardiovascular diseases (CVDs) has the highest mortality risk in USA and Europe with 15-20 million cases being reported annually. Cardiac Troponins (T and I) are well established protein biomarkers associated with heart muscle damage and point-of-care monitoring of both these two biomarkers has significant benefits on patient care. A flexible disposable electrochemical biosensor device comprising of vertically oriented zinc oxide (ZnO) nanostructures was developed for rapid and simultaneous screening of cardiac Troponin-I (cTnI) and cardiac-Troponin-T (cTnT) in a point-of-care sensor format. The biosensors were designed by selective hydrothermal growth of ZnO nanostructures onto the working electrodes of polyimide printed circuit board platforms, resulting in the generation of high density nanostructure ZnO arrays based electrodes. The size, density and surface terminations of the nanostructures were leveraged towards achieving surface confinement of the target cTnT and cTnI molecules on to the electrode surface. Multiplexing and simultaneous detection was achieved through sensor platform design comprising of arrays of Troponin functionalized ZnO nanostructure electrodes. The sensitivity and specificity of the biosensor was characterized using two types of electrochemical techniques; electrochemical impedance spectroscopy (EIS) and Mott-Schottky analysis on the same sensor platform to demonstrate multi-configurable modes. Limit of detection of 1pg/mL in human serum was achieved for both cTnI and cTnT. Cross reactivity analysis showed the selectivity of detecting cTnT and cTnI in human serum with wide dynamic range.

Flexible Molybdenum Electrodes towards Designing Affinity Based Protein Biosensors.

Molybdenum electrode based flexible biosensor on porous polyamide substrates has been fabricated and tested for its functionality as a protein affinity based biosensor. The biosensor performance was evaluated using a key cardiac biomarker; cardiac Troponin-I (cTnI). Molybdenum is a transition metal and demonstrates electrochemical behavior upon interaction with an electrolyte. We have leveraged this property of molybdenum for designing an affinity based biosensor using electrochemical impedance spectroscopy. We have evaluated the feasibility of detection of cTnI in phosphate-buffered saline (PBS) and human serum (HS) by measuring impedance changes over a frequency window from 100 mHz to 1 MHz. Increasing changes to the measured impedance was correlated to the increased dose of cTnI molecules binding to the cTnI antibody functionalized molybdenum surface. We achieved cTnI detection limit of 10 pg/mL in PBS and 1 ng/mL in HS medium. The use of flexible substrates for designing the biosensor demonstrates promise for integration with a large-scale batch manufacturing process.

Novel Nanomonitor ultra-sensitive detection of troponin T.

BACKGROUND: Troponin is the preferred biomarker for diagnosing myocardial infarction. Point of care devices have not matched the sensitivity of laboratory-based methods for measuring troponin. The Nanomonitor is a novel point-of-care device that uses the change in electrical impedance that occurs when a biomarker binds to its antibody, which is then correlated to the concentration of the target biomarker. METHODS: Performance characteristics of the Nanomonitor were evaluated and compared to a standard laboratory-based method. RESULTS: The limit of detection of the Nanomonior for troponin T was 0.0088ng/l. Total imprecission was 2.38% and 0.85% at troponin T concentrations of 73ng/l and 1800ng/l. The functional sensitivity (10% coeffecient of variation) was 0.329ng/l. The linear regression had a slope of 0.996 (95% confidence interval, 0.991, 1.002), r=1.00, and an intercept of 15.88ng/l (95% confidence interval, -68.39ng/l, 100.15ng/l). The mean difference between the assays was -7.54ng/l, determined by Bland-Altman analysis. CONCLUSION: The Nanomonitor preliminary results have favorable performance characteristics for detecting troponin T in patient blood, provide results in 15min, and are portable. More research is needed.