Electrochemical Investigation of Curcumin–DNA Interaction by Using Hydroxyapatite Nanoparticles–Ionic Liquids Based Composite Electrodes

Hydroxyapatite nanoparticles (HaP) and ionic liquid (IL) modified pencil graphite electrodes (PGEs) are newly developed in this assay. Electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and cyclic voltammetry (CV) were applied to examine the microscopic and electrochemical characterization of HaP and IL-modified biosensors. The interaction of curcumin with nucleic acids and polymerase chain reaction (PCR) samples was investigated by measuring the changes at the oxidation signals of both curcumin and guanine by differential pulse voltammetry (DPV) technique. The optimization of curcumin concentration, DNA concentration, and the interaction time was performed. The interaction of curcumin with PCR samples was also investigated by gel electrophoresis.     

Towards an implantable biochip for glucose and lactate monitoring using microdisc electrode arrays (MDEAs)

A complete electrochemical cell-on-a-chip that uses the MicroDisc Electrode Array (MDEA) working electrode (WE) design was evaluated for eventual intramuscular implantation for the continuous amperometric monitoring of glucose and lactate in an animal trauma model. The microfabricated ECC MDEA5037 comprises two discrete electrochemical cells-on-a-chip (ECCs), each with a reference, counter, and MDEA working electrode. Each MDEA comprises 37 microdiscs (diameter = 50 μm) arranged in a Hexagonal Closed Packed (HCP) arrangement with a center to center distance (d) of 100 μm. Cyclic Voltammetry (CV) and Electrical Impendence Spectroscopy (EIS) reveals that this device scales in its interfacial properties with a corresponding MDEA 050 device that comprises 5,184 microdiscs. Parallel development of miniaturized mixed-signal integrated electronics for wireless reprogramming, data acquisition and communication addresses the key issues involved in developing measurement electronics, AD/DA processing, power management and telemetry for implantable amperometric biosensors. A generalized electronics platform based on the Texas Instruments TI NC01101 chip has been developed that may be readily applied to many types of biotransducers with minor modifications.     

Biomimetic hydrogels for biosensor implant biocompatibility: electrochemical characterization using micro-disc electrode arrays (MDEAs)

Our interest is in the development of engineered microdevices for continuous remote monitoring of intramuscular lactate, glucose, pH and temperature during post-traumatic hemorrhaging. Two important design considerations in the development of such devices for in vivo diagnostics are discussed; the utility of micro-disc electrode arrays (MDEAs) for electrochemical biosensing and the application of biomimetic, bioactive poly(HEMA)-based hydrogel composites for implant biocompatibility. A poly(HEMA)-based hydrogel membrane containing polyethylene glycol (PEG) was UV cross-linked with tetraethyleneglycol diacrylate following application to MDEAs (50 μm discs) and to 250 μm diameter gold electrodes within 8-well culture ware. Cyclic voltammetry (CV) of the MDEAs revealed a reduction in the apparent diffusion coefficient of ferrocenemonocarboxylic acid (FcCO₂H), from 6.68 × 10⁻⁵ to 6.74 × 10⁻⁶ cm²/s for the uncoated and 6 μm thick hydrogel coated devices, respectively. Single frequency (4 kHz) temporal impedance measurements of the hydrogels in the 8-well culture ware showed a reversible 5% change in the absolute impedance of the hydrogels when exposed to a pH change between 6.1 to 7.2 and a 20% drop between pH 6.1 and 8.8.     

Nucleic acid detection technologies and marker molecules in bacterial diagnostics

There is a growing need for quick and reliable methods for microorganism detection and identification worldwide. Although traditional culture-based technologies are trustworthy and accurate at a relatively low cost, they are also time- and labor-consuming and are limited to culturable bacteria. Those weaknesses have created a necessity for alternative technologies that are capable for faster and more precise bacterial identification from medical, food or environmental samples. The most common current approach is to analyze the nucleic acid component of analyte solution and determine the bacterial composition according to the specific nucleic acid profiles that are present. This review aims to give an up-to-date overview of different nucleic acid target sequences and respective analytical technologies.     

Study on the therapeutic mechanism of the active principle of the Chinese drug Paeoniae Radix 801 through affinity biosensors IAsys Plus quartz crystal microbalance

Paeoniae Radix 801 (PR801), is one of the ac tive principles of the blood circulation activatingand stasis removing traditional Chinese medicine(TCM), which is extracted from Paeonia Lactiflo ra Pall(1). It has many physiological functions,such as inhibiting the formation of the blood plate let thromboxane A2 (TXA2), accelerating the for mation of artery inner prostaglandin (PGI2)(2), in hibiting the formation of thrombus and resistingblood platelet aggregation, …     

Paper-based analytical devices for clinical diagnosis: recent advances in the fabrication techniques and sensing mechanisms

Introduction: There is a significant interest in developing inexpensive portable biosensing platforms for various applications including disease diagnostics, environmental monitoring, food safety, and water testing at the point-of-care (POC) settings. Current diagnostic assays available in the developed world require sophisticated laboratory infrastructure and expensive reagents. Hence, they are not suitable for resource-constrained settings with limited financial resources, basic health infrastructure, and few trained technicians. Cellulose and flexible transparency paper-based analytical devices have demonstrated enormous potential for developing robust, inexpensive and portable devices for disease diagnostics. These devices offer promising solutions to disease management in resource-constrained settings where the vast majority of the population cannot afford expensive and highly sophisticated treatment options.

Areas covered: In this review, the authors describe currently developed cellulose and flexible transparency paper-based microfluidic devices, device fabrication techniques, and sensing technologies that are integrated with these devices. The authors also discuss the limitations and challenges associated with these devices and their potential in clinical settings.

Expert commentary: In recent years, cellulose and flexible transparency paper-based microfluidic devices have demonstrated the potential to become future healthcare options despite a few limitations such as low sensitivity and reproducibility.     

Astrocyte origin of activity-dependent release of ATP and glutamate in hippocampal slices: real-time measurement utilizing microelectrode biosensors

It is well known that astrocytic and neuronal transmitter release processes are important for signalling, and that activity-dependent release of adenosine nucleotides and transmitters occurs after stimulation. Neurons and astrocytes can account for the source of ATP efflux. In this issue of the BJP, Heinrich et al. characterized K⁺ depolarization-evoked release of ATP, adenosine and glutamate in hippocampal slices, utilizing microelectrode biosensors for simultaneous real-time recordings of multiple transmitter effluxes. They demonstrated efflux of ATP, adenosine and glutamate from hippocampus slices, in response to K⁺-depolarization, with distinct kinetics and mechanisms, suggesting a coordinated pattern of transmitter release. Surprisingly, it turned out that a considerable amount of the transmitter efflux measured under these conditions had a glial origin. For a long time, it was believed that the glial cell did not play a major role in neurotransmission, but the latter results somewhat change this view. The release of ATP and glutamate from glial cells under these conditions involved P2X7 receptors, and a source of adenosine accumulation independent of the metabolism of extracellular ATP was identified. This study also highlighted a novel use of multi-enzymatic microelectrode biosensors, which enabled a better characterization of transmitter release processes with higher temporal and spatial resolution than obtained previously. This technique was originally developed and used for the detection of purine release. In the present study, it was modified to identify the interplay between different transmitters, measured simultaneously in hippocampal slices.

LINKED ARTICLE

This article is a commentary on Heinrich et al., pp. 1003–1020 of this issue. To view this paper visit http://dx.doi.org/10.1111/j.1476-5381.2012.01932.x     

Pulse Transit Time Based on Piezoelectric Technique at the Radial Artery

Objectives. Pulse transit time (PTT) has shown its potential in relevant cardiovascular and cardiorespiratory studies. However, the use of photoplethysmography (PPG) in PTT measurement can be limited in events of poor peripheral perfusion. Uninterrupted PTT monitoring may also not be achievable when less cooperative patients distribute the PPG probe due to its prominent light source. Hence, there is a need for an alternative method to measure PTT in such incidents. Methods. In this study, the piezoelectric (PIEZO) technique to detect pulsations from a human wrist above the radial artery to estimate PTT is presented. 17 healthy adults (11 male; age range of 21–33 years) were recruited to compare PTT and heart rate (HR) differences between the PPG and PIEZO methods. These time-related derivations were made with respect to an electrocardiogram (ECG). Results. The timing consistency of the PIEZO transducer shows significant correlations (p < 0.01) to those derived from the ECG and a pulse oximeter. Particularly, there is a high level of agreement of < 1beat per minute (bpm) difference in HR estimates observed when compared to the two commercial devices in the respective Bland-Altman plots. Comparison of PTT obtained from the PIEZO transducer against the PPG signal shows constantly lower values due to the shorter path length it requires to propagate. A regression equation was formulated to relate the PTT values acquired from both these signals. Conclusions. Preliminary findings herein suggest that the PIEZO technique can be useful as an alternative for PTT monitoring. This shows promise to be more accommodating for less cooperative patients or those with insufficient peripheral perfusion.