Pranjal Chandra

Ultrasensitive and selective electrochemical diagnosis of breast cancer based on a hydrazine-Au nanoparticle-aptamer bioconjugate.

Human epidermal growth factor receptor 2 (HER2) and HER2-overexpressing breast cancer cells were detected using an electrochemical immunosensor combined with hydrazine and aptamer-conjugated gold nanoparticles (AuNPs). The sensor probe was fabricated by covalently immobilizing anti-HER2 onto a nanocomposite layer that was composed of self-assembled 2,5-bis(2-thienyl)-1H-pyrrole-1-(p-benzoic acid) (DPB) on AuNPs. The hydrazine-AuNP-aptamer bioconjugate, where the hydrazine reductant was directly attached onto AuNPs to avoid the nonspecific deposition of silver on the sensor surface, was designed and used to reduce silver ion for signal amplification selectively. The silver-stained target cells were visualized easily by the bare eye and an optical microscope, and the cells were quantitatively analyzed using stripping voltammetry. The parameters affecting the analytical response were optimized. The proposed sensor was capable of differentiating between HER2-positive breast cancer cells and HER2-negative cells. This method exhibited an excellent diagnosis method for the ultrasensitive detection of SK-BR-3 breast cancer cells in human serum samples with a detection limit of 26 cells/mL.

Label-free detection of kanamycin based on the aptamer-functionalized conducting polymer/gold nanocomposite.

Highly sensitive label-free detection of kanamycin is achieved with an aptamer sensor based on a conducting polymer/gold self-assembled nanocomposite. The sensor probe is fabricated by covalently immobilizing an in vitro selected DNA aptamer for kanamycin onto gold nanoparticle (AuNP)-comprised conducting polymer, poly-[2, 5-di-(2-thienyl)-1H-pyrrole-1-(p-benzoic acid)] (poly-DPB). The self-assembling of DPB on AuNP is investigated by TEM and UV-vis spectroscopy and the modification of the aptamer sensor is characterized using XPS and electrochemical impedance spectroscopy. The probe is applied to detect kanamycin by using voltammetric techniques. The sensor shows a pair of redox peaks around 0.26/ 0.08 V (vs. Ag/AgCl) for kanamycin captured by the aptamer-immobilized probe. The parameters that can affect the response, such as aptamer concentration, incubation time, temperature, and pH are optimized. The calibration plot shows a linear range from 0.05 μM to 9.0 μM kanamycin with a detection limit of 9.4±0.4 nM. The proposed aptamer sensor is examined with a real sample.

In vitro chloramphenicol detection in a Haemophilus influenza model using an aptamer-polymer based electrochemical biosensor.

A sensitive and selective electrochemical biosensor is developed for the determination of chloramphenicol (CAP) exploring its direct electron transfer processes in in-vitro model and pharmaceutical samples. This biosensor exploits a selective binding of CAP with aptamer, immobilized onto the poly-(4-amino-3-hydroxynapthalene sulfonic acid) (p-AHNSA) modified edge plane pyrolytic graphite. The electrochemical reduction of CAP was observed in a well-defined peak. A quartz crystal microbalance (QCM) study is performed to confirm the interaction between the polymer film and the aptamer. Cyclic voltammetry (CV) and square wave voltammetry (SWV) were used to detect CAP. The in-vitro CAP detection is performed using the bacterial strain of Haemophilus influenza. A significant accumulation of CAP by the drug sensitive H. influenza strain is observed for the first time in this study using a biosensor. Various parameters affecting the CAP detection in standard solution and in in vitro detection are optimized. The detection of CAP is linear in the range of 0.1-2500 nM with the detection limit and sensitivity of 0.02 nM and 0.102 µA/nM, respectively. CAP is also detected in the presence of other common antibiotics and proteins present in the real sample matrix, and negligible interference is observed.

Investigation on the downregulation of dopamine by acetaminophen administration based on their simultaneous determination in urine

A highly sensitive and selective method is developed for the simultaneous detection of dopamine (DA) and acetaminophen (AP) by reactive blue-4 (RB4) dye entrapped poly1,5-diaminonaphthalne (polyDAN) composite film layer. The polyDAN-RB4 composite is electrochemically developed at glassy carbon electrode. The polymeric film, characterized by XPS and SEM is able to catalyze the oxidation of DA and AP. Two well-defined oxidation peaks are observed in the differential pulse voltammogram (DPV). The experimental parameters affecting the analytical performance are optimized in terms of RB4 concentration, temperature, and pH. The dynamic range for DA and AP analysis is between 0.1-150 and 0.2-164μM with a detection limit of 0.061±0.002 and 0.083±0.003μM, respectively. The anionic form of the polyDAN-RB4 composite repels common metabolites present in serum and urine, and hence no interference is observed. The effect of AP on the DA concentrations in urine is also studied after the oral administration of a single as well as multiple doses. The DA concentrations have been found to decrease nearly 50±3% after prolonged AP administration.

Separation and simultaneous detection of anticancer drugs in a microfluidic device with an amperometric biosensor

A simple and highly sensitive method for simultaneous detection of anticancer drugs is developed by integrating the preconcentration and separation steps in a microfluidic device with an amperometric biosensor. An amperometric detection with dsDNA and cardiolipin modified screen printed electrodes are used for the detection of anticancer drugs at the end of separation channel. The preconcentration capacity is enhanced thoroughly using field amplified sample stacking and field amplified sample injection techniques. The experimental parameters affecting the analytical performances, such as pH, temperature, buffer concentration, water plug length, and detection potential are optimized. A reproducible response is observed during multiple injections of samples with a RSD <5%. The calibration plots are linear with the correlation coefficient between 0.9913 and 0.9982 over the range of 2-60 pM. The detection limits of four drugs are determined to be between 1.2 (± 0.05) and 5.5 (± 0.3) fM. The applicability of the device to the direct analysis of anticancer drugs is successfully demonstrated in a real spiked urine sample. Device was also examined for interference effect of common chemicals present in real samples.

An amperometric nanobiosensor using a biocompatible conjugate for early detection of metastatic cancer cells in biological fluid

Metastasis is the major cause of cancer-associated death in humans, and its early diagnosis will help clinicians to develop suitable therapeutic strategies which may save life of cancer patients. In this direction, we designed an amperometric biosensor using a biocompatible conjugate to diagnose cancer metastasis by detecting epithelial cell adhesion molecule expressing metastatic cancer cells (Ep-MCCs). The sensor probe is fabricated by immobilizing monoclonal capture antibody (CapAnti) on the gold nanoparticles (AuNPs)/conducting polymer composite layer. The detection relies on a sandwich-type approach using a bioconjugate composed of reporter antibody (RepAnti), nanostructured collagen (nCOL), AuNPs, and hydrazine (Hyd) which served as a nonenzymatic electrocatalyst for the reduction of H2O2. The binding of Ep-MCCs with the sensor probe was confirmed using electrochemical impedance spectroscopy, cyclic voltammetry, and chronoamperometry. A dynamic range for the Ep-MCCs detection is determined between 45 and 100,000 Ep-MCCs/mL with the detection limit of 28±3 Ep-MCCs/mL. The proposed immunosensor is successfully applied to detect Ep-MCCs in serum and mixed cell samples and interferences due to nontarget cells and molecules present in the real sample matrix are also examined. The early stage of Ep-MCCs was examined by fluorescence-activated cell sorting assay, which confirms that the developed biosensor has detected Ep-MCCs in its early stage.

Paper based diagnostics for personalized health care: Emerging technologies and commercial aspects.

Personalized health care (PHC) is being appreciated globally to combat clinical complexities underlying various metabolic or infectious disorders including diabetes, cardiovascular, communicable diseases etc. Effective diagnoses majorly depend on initial identification of the causes which are nowadays being practiced in disease-oriented approach, where personal health profile is often overlooked. The adoption of PHC has shown significantly improved diagnoses in various conditions including emergency, ambulatory, and remote area. PHC includes personalized health monitoring (PHM), which is its integral part and may provide valuable informations on various clinical conditions. In PHC, bio-fluids are analyzed using various diagnostic devices including lab based equipment and biosensors. Among all types of biosensing systems, paper based biosensors are commercially attracted due to its portability, easy availability, cheaper manufacturing cost, and transportability. Not only these, various intrinsic properties of paper has facilitated the development of paper based miniaturized sensors, which has recently gained ASSURED (Affordable, Sensitive, Specific, User-friendly, Rapid and Robust, Equipment free, Deliverable to all end-users) status for point of care diagnosis in miniaturized settings. In this review, importance of paper based biosensors and their compatibility for affordable and low cost diagnostics has been elaborated with various examples. Limitations and strategies to overcome the challenges of paper biosensor have also been discussed. We have provided elaborated tables which describe the types, model specifications, sensing mechanisms, target biomarkers, and analytical performance of the paper biosensors with their respective applications in real sample matrices. Different commercial aspects of paper biosensor have also been explained using SWOT (Strength, Weakness, Opportunities, Threats) analysis.

A review on determination of steroids in biological samples exploiting nanobio-electroanalytical methods

The applications of nanomaterial modified sensors, molecularly imprinting polymer based, aptamer based, and immunosensors have been described in the determination of steroids using electroanalytical techniques. After a brief description of the steroids and assays in biological fluids, the principles of electrochemical detection with the advantages and the limitations of the various sensors are presented. The nanomaterial modified sensors catalyze the oxidation/reduction of steroids and are suitable for sensing them in environmental samples and biological fluids. The determination of steroids based on their reduction has been found more useful in comparison to oxidation as the common metabolites present in the biological fluids do not undergo reduction in the usual potential window and hence, do not interfere in the determination. The sensors based on immunosensors and aptamers were found more sensitive and selective for steroid determination. Conducting polymer modified bio-sensors and microchip devices are suggested as possible future prospects for the ultra sensitive and simultaneous determination of steroids and their metabolites in various samples.

Simultaneous detection of antibacterial sulfonamides in a microfluidic device with amperometry.

A highly sensitive and robust method for simultaneous detection of five sulfonamide drugs is developed by integrating the preconcentration and separation steps in a microfluidic device. An ampetrometry is performed for the selective detection of sulfonamides using an aluminum oxide-gold nanoparticle (Al(2)O(3)-AuNPs) modified carbon paste (CP) electrode at the end of separation channel. The preconcentration capacity of the channel is enhanced by using the field amplified sample stacking and the field amplified sample injection techniques. The experimental parameters affecting the analytical performances, such as pH, % of Al(2)O(3), volume of AuNPs, buffer concentration, and water plug length are optimized. A reproducible response is observed during the multiple injections of samples with RSDs<4%. The calibration plots are linear with the correlation coefficient between 0.991 and 0.997 over the range between 0.01 and 2025pM. The detection limits of five drugs are determined to be between 0.91 (±0.03) and 2.21 (±0.09)fM. The interference effects of common biological compounds are also investigated and the applicability of the method to the direct analysis of sulfonamides in real meat samples is successfully demonstrated. Long term stability of the modified electrode was also investigated.

Detection of norfloxacin and monitoring its effect on caffeine catabolism in urine samples

A multi-walled carbon nano tube (MWCNT) modified pyrolytic graphite (MPG) electrode is prepared and applied to detect norfloxacin (NFX) based on its electrochemical reduction. The experimental parameters affecting the NFX determination were optimized in terms of MWCNT amount, pH, reaction time, and square wave frequency. The dynamic range for the NFX analysis ranged between 1.2 and 1000µM with a detection limit of 40.6±3.3nM. The effect of NFX on the catabolism of caffeine has been studied by determining its concentration in the urine samples after the prolonged administration of NFX using the MPG electrode. The results show that the catabolism of caffeine is inhibited by ~65% after five days of NFX administration, consequently the caffeine concentration in the urine sample is increased, which is reflected in terms of ~2.5 times increase in the peak current of caffeine. The determinations of NFX and caffeine were selective and the method was successfully applied in biological fluids and pharmaceutical tablets for the test compound analysis. In future this method can be useful for the selective determination of NFX and studying its effect on caffeine catabolism.