Electrochemical Amperometric Biosensor Applications of Nanostructured Metal Oxides: A Review

Biological sensors have been extensively investigated during the last few decades. Among the diverse facets of biosensing research, nanostructured metal oxides (NMOs) offer a plethora of potential benefits. In this article, we provide a thorough review on the sensor applications of NMOs such as glucose, cholesterol, urea, and uric acid. A detailed analysis of the literature is presented with organized tables elaborating the fundamental characteristics of sensors including the sensitivity, limit of detection, detection range, and stability parameters such as duration, relative standard deviation, and retention. Further analysis was provided through an innovative way of displaying the sensitivity and linear range of sensors in figures. As the unique properties of NMOs offer potential applications to various research fields, we believe this review is both timely and provides a comprehensive analysis of the current state of NMO applications

Comparison of the planimetry and point-counting methods for the assessment of the size of the mandible cysts on orthopantomograms

Objective: The purpose of this study is to compare the computer-assisted planimetry and point-counting methods in evaluating the sizes of the mandibular cysts with respect to their agreement and the time required to analyze. Study Design: The surface areas of 46 mandibular cyst lesions on orthopantomograms were estimated using the point-counting and computer-assisted planimetry methods. Three observers evaluated the outlined areas twice, using the point-counting (PC) and computer-assisted planimetry (CAP) methods with an interval of two weeks. In the planimetry technique, digitalized images and ImageJ software were used to measure the surface area of the half mandibles and cysts. The grids were superimposed over the same images and the number of points hitting the interested structures was counted for the point-counting technique. The projection area fraction (PAF) of the cysts within the mandible was estimated using the obtained values by means of the two techniques. Intraclass correlation coefficient was used to assess the level of agreement between the two methods. Inter-rater reliability analysis using the Kappa statistic was performed to determine consistency among raters. Results: CAP and PC techniques showed consistent intra-observer values in all observers. Intraclass correlation between CAP and PC measurements of first, second and third observers were found to be 0.9986, 0.9988 and 0.9994 respectively. The durations of PC technique was 32% higher than the CAP technique. Conclusion: PC and CAP methods were seemed to show sufficient agreement to be used interchangeably. The main disadvantage of the PC analysis is it takes more time than CAP method

Stereological analysis of sciatic nerve in chickens following neonatal pinealectomy: an experimental study

<p>Abstract</p> <p>Background</p> <p>Although the injury to the peripheral nervous system is a common clinical problem, understanding of the role of melatonin in nerve degeneration and regeneration is incomplete.</p> <p>Methods</p> <p>The current study investigated the effects of neonatal pinealectomy on the sciatic nerve microarchitecture in the chicken. The chickens were divided into two equal groups: unpinealectomized controls and pinealectomized chickens. At the end of the study, biochemical examination of 10 sciatic nerve samples from both groups was performed and a quantitative stereological evaluation of 10 animals in each group was performed. The results were compared using Mann-Whitney test.</p> <p>Results</p> <p>In this study, the results of axon number and thickness of the myelin sheath of a nerve fiber in newly hatched pinealectomy group were higher than those in control group. Similarly, surgical pinealectomy group had significantly larger axonal cross-sectional area than the control group (p < 0.05). In addition, the average hydroxyproline content of the nerve tissue in neonatal pinealectomy group was higher than those found in control group. Our results suggest that melatonin may play a role on the morphologic features of the peripheral nerve tissue and that melatonin deficiency might be a pathophysiological mechanism in some degenerative diseases of peripheral nerves. The changes demonstrated by quantitative morphometric methods and biochemical analysis has been interpreted as a reflection of the effects of melatonin upon nerve tissue.</p> <p>Conclusion</p> <p>In the light of these results from present animal study, changes in sciatic nerve morphometry may be indicative of neuroprotective feature of melatonin, but this suggestion need to be validated in the human setting.</p

A First-Principle Study of Nanostructured CuO Thin Film-Based Caffeine Sensing Scheme

In this study, we demonstrated the feasibility of nanostructured CuO thin film usage for caffeine sensing. Our morphological studies revealed that ellipse- or spiral-shaped nanostructured were formed with good crystal qualities. It was shown that the film thickness was decreased from 803 nm to 717 nm with annealing. Better crystalline quality of annealed films resulted in higher sensing response. Moreover, caffeine sensing response time was decreased to 19 s from 28 s for annealed films compared to as-grown CuO films. Both films exhibited excellent linearity with higher than 0.93 R2 values for the caffeine values from 0.5 mM to 10 mM, which is the range for most caffeinated hot and cold beverages. Caffeine is considered the only legal stimulant and its excessive use is not healthy. Knowing the caffeine content of beverages using portable, cheap sensor devices will be beneficial for the health-conscious society. We believe our sensing scheme in using nanostructured semiconductor thin films will pave the way to ultimately create advanced materials-based portable sensor devices

Simple and Low-Cost Synthesis of Al-doped ZnO/CuO Composite Nanowires for Highly Efficient Hydration Level Sensing

In this paper, we report on our investigation of the impact of Al doping on the primary physical properties of SILAR fabricated CuO/ZnO composite nanowires. Our characterization on surface and structural analysis showed that we were able to lightly dope the nanocomposites effectively using the SILAR method, which is cost-effective and repeatable. Conductivity of the Al-doped films changed significantly which resulted in greater sensing response for hydration. We utilized artificial sweat solutions to characterize the sensing response of the films and we demonstrated that sensing response almost doubled with Al doping. Transient response of sweat application also showed that response times were less than 10 s for 2% Al-doping. We conclude that Al doping on CuO/ZnO nanocomposites is an excellent candidate to be utilized for hydration sensing through sweat

Alkali Metals (Na, K) Doped ZnO/CuO Composite Films for Real-time Tracking of Sweat Loss

Real-time sweat rate monitoring provides clinically proper directives for preventive medicine and disease diagnosis. This research represents an attempt to develop a semiconductor-based nanostructured sensor for monitoring sweat rate using a ZnO/CuO composite thin film. A series of alkali metals (sodium, Na; potassium, K) doped ZnO/CuO composite samples were fabricated on soda lime glass substrates by the Successive Ionic Layer Adsorption and Reaction method. The sweat solution sensing response characterization exhibited promising sensing behavior under room conditions. The Na- and K-doped samples showed a pronounced response at low and high concentrations of the sweat solution. While the undoped composite film responds to the high concentration sweat solution (117.90 mM) with a sensitivity of 4.10, this value increases up to 9.15 for the 2.0% Na-doped samples. In addition, the response time shortens from 6 s to 4 s for 2.0% Na substitutions. Pristine, 2.0% Na and 2.0% K-substituted ZnO/CuO composites exhibit great linearity with linear regression ranges, R2, of 0.958, 0.971, and 0.984, respectively. We concluded that doping of ZnO/CuO composites with alkali metals Na and K is a good candidate for real-time tracking of sweat loss as biological evidence