Surface plasmon microarray and voltage-driven biocatalysis for drug development and bioelectronics

The objectives of the research described in this dissertation are driven with a broader motivation to provide scientific solutions to real world problems related to human health and cleaner energy. Under global health issues, there are many challenges that need to be addressed, specifically in the laborious drug development process and characterization of small-molecule cancer drugs. The research strategies described in this work focus on developing analytical solutions for drug candidate identification, preclinical metabolite screening, and quality assurance of active pharmaceutical ingredients. A surface plasmon methodology was developed to study binding kinetics of oncogenic protein-protein interactions and their inhibition by small-molecule drugs. Additionally, a rapid one-step construction of the human liver membrane bioelectrodes for inexpensive, electrochemical drug metabolism and inhibition was formulated. Thirdly, the applicability of the screen printed electrodes was validated towards single drop electrocatalysis of pharmaceuticals as a cost-effective and instant analytical tool to determine the purity of an active chemical form of a drug. Under the focus of biocatalysis, high efficient nanostructure bioelectrode designs have been investigated for model catalytic reactions

Electrochemical and Colorimetric Nanosensors for Detection of Heavy Metal Ions: A Review

Human exposure to acute and chronic levels of heavy metal ions are linked with various health issues, including reduced children’s intelligence quotients, developmental challenges, cancers, hypertension, immune system compromises, cytotoxicity, oxidative cellular damage, and neurological disorders, among other health challenges. The potential environmental HMI contaminations, the biomagnification of heavy metal ions along food chains, and the associated risk factors of heavy metal ions on public health safety are a global concern of top priority. Hence, developing low-cost analytical protocols capable of rapid, selective, sensitive, and accurate detection of heavy metal ions in environmental samples and consumable products is of global public health interest. Conventional flame atomic absorption spectroscopy, graphite furnace atomic absorption spectroscopy, atomic emission spectroscopy, inductively coupled plasma–optical emission spectroscopy, inductively coupled plasma–mass spectroscopy, X-ray diffractometry, and X-ray fluorescence have been well-developed for HMIs and trace element analysis with excellent but varying degrees of sensitivity, selectivity, and accuracy. In addition to high instrumental running and maintenance costs and specialized personnel training, these instruments are not portable, limiting their practicality for on-demand, in situ, field study, or point-of-need HMI detection. Increases in the use of electrochemical and colorimetric techniques for heavy metal ion detections arise because of portable instrumentation, high sensitivity and selectivity, cost-effectiveness, small size requirements, rapidity, and visual detection of colorimetric nanosensors that facilitate on-demand, in situ, and field heavy metal ion detections. This review highlights the new approach to low-cost, rapid, selective, sensitive, and accurate detection of heavy metal ions in ecosystems (soil, water, air) and consumable products. Specifically, the review highlights low-cost, portable, and recent advances in smartphone-operated screen-printed electrodes (SPEs), plastic chip SPES, and carbon fiber paper-based nanosensors for environmental heavy metal ion detection. In addition, the review highlights recent advances in colorimetric nanosensors for heavy metal ion detection requirements. The review provides the advantages of electrochemical and optical nanosensors over the conventional methods of HMI analyses. The review further provides in-depth coverage of the detection of arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), mercury (Hg), manganese (Mn), nickel (Ni), lead (Pb), and zinc (Zn) ions in the ecosystem, with emphasis on environmental and biological samples. In addition, the review discusses the advantages and challenges of the current electrochemical and colorimetric nanosensors protocol for heavy metal ion detection. It provides insight into the future directions in the use of the electrochemical and colorimetric nanosensors protocol for heavy metal ion detection

Hybrid paper and 3D-printed microfluidic device for electrochemical detection of Ag nanoparticle labels

In the present article we report a new hybrid microfluidic device (hyFlow) comprising a disposable paper electrode and a three-dimensional (3D) printed plastic chip for the electrochemical detection of a magnetic bead-silver nanoparticle (MB-AgNP) bioconjugate. This hybrid device evolved due to the difficulty of incorporating micron-scale MBs into paper-only fluidic devices. Specifically, paper fluidic devices can entrap MB-containing conjugates within their cellulose or nitrocellulose fiber matrix. The hyFlow system was designed to minimize such issues and transport MB conjugates more efficiently to the electrochemical detection zone of the device. The hyFlow system retains the benefit of fluid transport by pressure-driven flow, however, no pump is required for its operation. The hyFlow device is capable of detecting either pre-formed MB-AgNP conjugates or conjugates formed in situ. The detection limit of AgNPs using this device is 12 pM, which represents just 22 AgNPs per MB

Enzymatic versus Electrocatalytic Oxidation of NADH at Carbon-Nanotube Electrodes Modified with Glucose Dehydrogenases: Application in a Bucky-Paper-Based Glucose Enzymatic Fuel Cell

International audienc

Mechanistic Insights into Voltage-Driven Biocatalysis of a Cytochrome P450 Bactosomal Film on a Self-Assembled Monolayer

Simple construction of biocatalytically active films of cytochrome P450 (CYP) bactosomes is quite useful for low-cost, stereoselective, and nicotinamide adenine dinucleotide phosphate hydride-free drug metabolism assays, biosensing, and biocatalytic applications. We report here real-time monitoring of the formation of biocatalytically active films of membrane-bound human CYP 2C9 or 3A4 expressed with CYP reductase (CPR) in <i>Escherichia coli</i> (so-called bactosomes) on a cysteamine self-assembled monolayer of gold-infused quartz crystals. The CYP 2C9+CPR-containing bactosomes exhibited oxygen reduction currents and metabolite yields greater than those of the CYP 3A4+CPR film. The electrocatalytic property correlated with the greater levels of CPR activity and the amount of CYP 2C9 in the CYP 2C9+CPR bactosomes than in the CYP 3A4+CPR bactosomes. The electron mediating role of CPR in the CYP 2C9 bactosomal film (<i>E</i>°′ = −450 mV vs Ag/AgCl) toward electrocatalytic oxygen reduction and hydroxylation of diclofenac was experimentally identified by comparing the film with bactosomes expressed with either CYP 2C9 (<i>E</i>°′ = −310 mV) or CPR (<i>E</i>°′ = −450 mV). The onset of oxygen reduction potentials correlated with the formal potentials of CYP and CYP+CPR films and revealed the electrocatalysis by CYP alone or in association with CPR. Furthermore, an ∼2-fold increase in the level of 4-hydroxydiclofenac product formation supported the favorable role of added catalase (hydrogen peroxide scavenger) in preventing damage by reactive oxygen species to the membrane-bound CYP or CYP+CPR bactosomes. The insignificant role of a peroxide shunt pathway for electrocatalysis in the case of the membrane-bound CYP film alone (unlike membrane-free isolated soluble CYP enzymes) and the electron mediation by CPR from the electrode to initiate CYP catalysis in the CYP+CPR bactosomes were discovered in this study. In conclusion, this report describes voltage-driven biocatalysis by bactosomal CYP films with new mechanistic insights into the formal potentials and electrocatalytic pathways of membrane-bound CYP films either alone or in association with CPR in the membrane

A Simple Construction of Electrochemical Liver Microsomal Bioreactor for Rapid Drug Metabolism and Inhibition Assays

In order to design a green microsomal bioreactor on suitably identified carbon electrodes, it is important to understand the direct electrochemical properties at the interfaces between various carbon electrode materials and human liver microsomes (HLM). The novelty of this work is on the investigation of directly adsorbed HLM on different carbon electrodes with the goal to develop a simple, rapid, and new bioanalytical platform of HLM useful for drug metabolism and inhibition assays. These novel biointerfaces are designed in this study by a one step adsorption of HLM directly onto polished basal plane pyrolytic graphite (BPG), edge plane pyrolytic graphite (EPG), glassy carbon (GC), or high-purity graphite (HPG) electrodes. The estimated direct electron transfer (ET) rate constant of HLM on the smooth GC surface was significantly greater than that of the other electrodes. On the other hand, the electroactive surface coverage and stability of microsomal films were greater on highly surface defective, rough EPG and HPG electrodes compared to the smooth GC and less defective hydrophobic BPG surfaces. The presence of significantly higher oxygen functionalities and flatness of the GC surface is attributed to favoring faster ET rates of the coated layer of thin HLM film compared to other electrodes. The cytochrome P450 (CYP)-specific bioactivity of the liver microsomal film on the catalytically superior, stable HPG surface was confirmed by monitoring the electrocatalytic conversion of testosterone to 6β-hydroxytestosterone and its inhibition by the CYP-specific ketoconazole inhibitor. The identification of optimal HPG and EPG electrodes to design biologically active interfaces with liver microsomes is suggested to have immense significance in the design of one-step, green bioreactors for stereoselective drug metabolite synthesis and drug metabolism and inhibition assays

Label-Free Real-Time Microarray Imaging of Cancer Protein–Protein Interactions and Their Inhibition by Small Molecules

A rapid optical microarray imaging approach for anticancer drug screening at specific cancer protein–protein interface targets with binding kinetics and validation by a mass sensor is reported for the first time. Surface plasmon resonance imager (SPRi) demonstrated a 3.5-fold greater specificity for interactions between murine double minute 2 protein (MDM2) and wild-type p53 over a nonspecific p53 mutant in a real-time microfluidic analysis. Significant percentage reflectivity changes (Δ%<i>R</i>) in the SPRi signals and molecular-level mass changes were detected for both the MDM2–p53 interaction and its inhibition by a small-molecule Nutlin-3 drug analogue known for its anticancer property. We additionally demonstrate that synthetic, inexpensive binding domains of interacting cancer proteins are sufficient to screen anticancer drugs by an array-based SPRi technique with excellent specificity and sensitivity. This imaging array, combined with a mass sensor, can be used to study quantitatively any protein–protein interaction and screen for small molecules with binding and potency evaluations

QCM Sensor Arrays, Electroanalytical Techniques and NIR Spectroscopy Coupled to Multivariate Analysis for Quality Assessment of Food Products, Raw Materials, Ingredients and Foodborne Pathogen Detection: Challenges and Breakthroughs

Quality checks, assessments, and the assurance of food products, raw materials, and food ingredients is critically important to ensure the safeguard of foods of high quality for safety and public health. Nevertheless, quality checks, assessments, and the assurance of food products along distribution and supply chains is impacted by various challenges. For instance, the development of portable, sensitive, low-cost, and robust instrumentation that is capable of real-time, accurate, and sensitive analysis, quality checks, assessments, and the assurance of food products in the field and/or in the production line in a food manufacturing industry is a major technological and analytical challenge. Other significant challenges include analytical method development, method validation strategies, and the non-availability of reference materials and/or standards for emerging food contaminants. The simplicity, portability, non-invasive, non-destructive properties, and low-cost of NIR spectrometers, make them appealing and desirable instruments of choice for rapid quality checks, assessments and assurances of food products, raw materials, and ingredients. This review article surveys literature and examines current challenges and breakthroughs in quality checks and the assessment of a variety of food products, raw materials, and ingredients. Specifically, recent technological innovations and notable advances in quartz crystal microbalances (QCM), electroanalytical techniques, and near infrared (NIR) spectroscopic instrument development in the quality assessment of selected food products, and the analysis of food raw materials and ingredients for foodborne pathogen detection between January 2019 and July 2020 are highlighted. In addition, chemometric approaches and multivariate analyses of spectral data for NIR instrumental calibration and sample analyses for quality assessments and assurances of selected food products and electrochemical methods for foodborne pathogen detection are discussed. Moreover, this review provides insight into the future trajectory of innovative technological developments in QCM, electroanalytical techniques, NIR spectroscopy, and multivariate analyses relating to general applications for the quality assessment of food products