Exploration of 2-Dimensional Bio-functionalized Phosphorene Nanosheets (Black Phosphorous) for Label free Haptoglobin Electro-immunosensing Applications

Satish Tuteja and Suresh Neethirajan

Nanotechnology (Link


We report on the development of an antibody-functionalized interface based on electrochemically active liquid-exfoliated two-dimensional phosphorene (Ph) nanosheets—also known as black phosphorous nanosheets—for the label-free electrochemical immunosensing of a haptoglobin (Hp) biomarker, a clinical marker of severe inflammation. The electrodeposition has been achieved over the screen-printed electrode (SPE) using liquid-assisted ultrasonically exfoliated black phosphorus nanosheets. Subsequently, Ph-SPEs bioconjugated with Hp antibodies (Ab), using electrostatic interactions via a poly-L-lysine (PLL) linker for biointerface development. Electrochemical analysis demonstrates that the Ab-modified Ph-SPEs (Ab@Ph-SPE) exhibit enhanced electroconducting behavior as compared to the pristine electrodes. This Ab-functionalized phosphorene-based electrochemical immunosensor platform has demonstrated remarkable sensitivity and specificity, having a dynamic linear response range from 0.01 mg/mL to 10 mg/mL for Hp in standard and serum samples with a low detection limit (~0.011 mg/mL) using the label-free electrochemical technique. The sensor electrodes were also studied with other closely relative interferents to investigate cross reactivity and specificity. This strategy opens up avenues to POC (point-of-care) and on-farm livestock disease monitoring technologies for multiplexed diagnosis in complex biological samples such as serum. The technique is simple in fabrication and provides an analytical response in less than 60 seconds.

Non-invasive Label-free Detection of Cortisol and Lactate using Graphene Embedded Screen-printed Electrode

Satish Tuteja, Connor Ormbsy, Suresh Neethirajan

Nano-Micro Letters (Link)


A sensitive and specific immunosensor for the detection of the hormones cortisol and lactate in human or animal biological fluids, such as sweat and saliva, was devised using the label-free electrochemical chronoamperometric technique. By using these fluids instead of blood, the biosensor becomes non-invasive and is less stressful to the end-user, who may be a small child or a farm animal. Electro-reduced graphene oxide (e-RGO) was used as a synergistic platform for signal amplification and template for bioconjugation for the sensing mechanism on a screen-printed electrode. The cortisol and lactate antibodies were bioconjugated to the e-RGO using covalent carbodiimide chemistry. Label-free electrochemical chronoamperometric detection was used to analyze the response to the desired bio-molecules over the wide detection range. A detection limit of 0.1 ng/mL for cortisol and 0.1 mM for lactate were established and a correlation between concentration and current was observed. A portable, handheld potentiostat assembled with Bluetooth communication and battery operation enables the developed system for point-of-care applications. A sandwich like structure to contain the sensing mechanisms as a prototype were designed to secure the biosensor to skin and use capillary action to draw sweat or other fluids towards the sensing mechanism. Overall, the immunosensor shows remarkable specificity, sensitivity as well as the non-invasive and point-of-care capabilities, allows the biosensor to be used as a versatile sensing platform in both developed and developing countries.

Optoelectronic fowl adenovirus detection based on local electric field enhancement on graphene quantum dots and gold nanobundle hybrid

Syed Rahin Ahmed, Jack Mogus, Rohit Chand, Eva Nagy, Suresh Neethirajan

Biosensors and Bioelectronics  (Link)




    • Optoelectronic biosensor to detect Fowl Adenovirus was developed.• The developed biosensors was based on gold nanobundles-graphene quantum dots hybrids.• Assay had a detection limit of 8.75 PFU/mL with linear range from 10 to 10,000 PFU/mL.• Proposed sensing strategy was 100 times more sensitive than conventional ELISA method.• Present bioassay may become a new strategy for biological and chemical molecules detection.



An optoelectronic sensor is a rapid diagnostic tool that allows for an accurate, reliable, field-portable, low-cost device for practical applications. In this study, template-free In situ gold nanobundles (Au NBs) were fabricated on an electrode for optoelectronic sensing of fowl adenoviruses (FAdVs). Au NB film was fabricated on carbon electrodes working area using L(+) ascorbic acid, gold chroloauric acid and poly-l-lysine (PLL) through modified layer-by-layer (LbL) method. A scanning electron microscopic (SEM) image of the Au NBs revealed a NB-shaped Au structure with many kinks on its surface, which allow local electric field enhancement through light–matter interaction with graphene quantum dots (GQDs). Here, GQDs were synthesized through an autoclave-assisted method. Characterization experiments revealed blue-emissive, well-dispersed GQDs that were 2–3 nm in size with the fluorescence emission peak of GQDs located at 405 nm. Both Au NBs and GQDs were conjugated with target FAdVs specific antibodies that bring them close to each other with the addition of target FAdVs through antibody–antigen interaction. At close proximity, light–matter interaction between Au NBs and QDs produces a local electric signal enhancement under Ultraviolet–visible (UV–visible) light irradiation that allows the detection of very low concentrations of target virus even in complex biological media. A proposed optoelectronic sensor showed a linear relationship between the target FAdVs and the electric signal up to 10 Plaque forming unit (PFU)/mL with a limit of detection (LOD) of 8.75 PFU/mL. The proposed sensing strategy was 100 times more sensitive than conventional ELISA method.


Advances in biosensors and optical assays for diagnosis and detection of malaria

K.V. Ragavan, Sanni Kumar, Shiva Swaraj, Suresh Neethirajan

Biosensors and Bioelectronics (Link)  





Vector-borne diseases are a major concern for human health globally, especially malaria in densely populated, less developed, tropical regions of the world. Malaria causes loss of human life and economic harm, and may spread through travelers to new regions. Though there are sufficient therapeutics available for the effective treatment and cure of malaria, it infects millions of people and claims several thousand lives every year. Early diagnosis of the infection can potentially prevent the spread of disease, save lives, and mitigate the financial impact. Conventional analytical techniques are being widely employed for malaria diagnosis, but with low sensitivity and selectivity. Due to the poor-resource settings where malaria outbreaks often occur, most conventional diagnostic methods are not affordable and hence not effective in detection and controlling the spread of the infection. However, biosensors have improved the scope for affordable malaria diagnosis. Advances in biotechnology and nanotechnology have provided novel recognition materials and transducer elements, discoveries which allow the fabrication of affordable biosensor platforms with improved attributes. The present work covers the advancement in biosensors with an introduction to malaria, followed by conventional methods of malaria diagnosis, malaria markers, novel recognition elements and the biosensor principle. Finally, a proactive role and a perspective on developed biosensor platforms are discussed with potential biomedical applications.

Isothermal DNA amplification with functionalized graphene and nanoparticle assisted electroanalysis for rapid detection of Johne’s disease

Rohit Chand, Yi Lan Wang, David Kelton, Suresh Neethirajan

Sensors and Actuators B: Chemical (Link) 


Johnes disease (JD), which is caused by Mycobacterium avium subspecies paratuberculosis (MAP), is a bacterial infection of the intestinal tract of ruminants. JD is a cause of significant economic and animal loss throughout the world. Sensitive, selective, and on-site detection of MAP in clinical samples has always been a problem. This study outlines a loop-mediated isothermal DNA amplification (LAMP) and electrochemical analysis-based point-of-care (POC) detection methodology for MAP. LAMP contributed to the selective amplification of MAP DNA, and electrochemical analysis assisted in the rapid and sensitive analysis of LAMP products. A graphene and tetracycline (TET)-functionalized screen printed carbon electrode was used for the selective detection of magnesium pyrophosphate (Mg2P2O7) produced during the LAMP. The Mg2P2O7 obtained from the LAMP was sandwiched on the electrode between TET and zirconium dioxide nanoparticles (ZrO2). The complexation of Mg2P2O7 triggered an electrochemical change that was monitored using electrochemical techniques. The complexation mechanism and functionalized electrodes were characterized using several microscopic, spectroscopic, and electrochemical techniques. The optimized MAP biosensor was employed to detect a range of MAP DNA concentrations. Using electrochemical impedance spectroscopy, a detection limit of 6.37 aM (20 fg/μL) with a detection range of 6.37 aM (20 fg/μL) to 6.37 pM (20 ng/μL) for MAP DNA was obtained. The application of the biosensor was also assessed by MAP detection in clinical fecal samples. The biosensor could easily detect the presence of MAP in bovine fecal samples and showed good co-relation with other conventional techniques. Therefore, the developed biosensor has the potential to be used for POC detection of JD in animals.

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