A comparative study of graphene–hydrogel hybrid bionanocomposites for biosensing

The Analyst ◽  
2015 ◽  
Vol 140 (5) ◽  
pp. 1466-1476 ◽  
Author(s):  
S. L. Burrs ◽  
D. C. Vanegas ◽  
M. Bhargava ◽  
N. Mechulan ◽  
P. Hendershot ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Comparative Study ◽  
Response Time ◽  
Surface Area ◽  
Silk Fibroin ◽  
Cellulose Nanocrystals ◽  
Limit Of Detection ◽  
Enzymatic Biosensors ◽  
The Comparative Study ◽  
Electroactive Surface Area

Graphene–nanometal enzymatic biosensors were prepared using hydrogels composed of chitosan, poly-N-isopropylacrylamide, silk fibroin, or cellulose nanocrystals. The comparative study investigated electroactive surface area, charge transfer, response time, limit of detection, and sensitivity toward alcohols.

scholarly journals Structural refinement and electrochemical properties of one dimensional (ZnO NRs)1−x(CNs)x functional hybrids for serotonin sensing studies

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Sajid B. Mullani ◽  
Ananta G. Dhodamani ◽  
Annadanesh Shellikeri ◽  
Navaj B. Mullani ◽  
Anita K. Tawade ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Electrochemical Properties ◽  
Surface Area ◽  
Limit Of Detection ◽  
Zno Nanorods ◽  
Charge Transfer Resistance ◽  
Transfer Resistance ◽  
Bet Analysis ◽  
Lower Charge ◽  
Lower Charge Transfer Resistance

Abstract Herein, the efficient serotonin (5-HT) sensing studies have been conducted using the (ZnO NRs)1−x(CNs)x nanocomposites (NCs) having appropriate structural and electrochemical properties. Initially, the different compositions of ZnO nanorods (NRs), with varying content of carbon nanostructures (CNs=MWCNTs and RGO), are prepared using simple in-situ wet chemical method and thereafter these NCs have been characterized for physico-chemical properties in correlation to the 5-HT sensing activity. XRD Rietveld refinement studies reveal the hexagonal Wurtzite ZnO NRs oriented in (101) direction with space group ‘P63mc’ and both orientation as well as phase of ZnO NRs are also retained in the NCs due to the small content of CNs. The interconnectivity between the ZnO NRs with CNs through different functional moieties is also studied using FTIR analysis; while phases of the constituents are confirmed through Raman analysis. FESEM images of the bare/NCs show hexagonal shaped rods with higher aspect ratio (4.87) to that of others. BET analysis and EIS measurements reveal the higher surface area (97.895 m2/g), lower charge transfer resistance (16.2 kΩ) for the ZCNT 0.1 NCs to that of other NCs or bare material. Thereafter, the prepared NCs are deposited on the screen printed carbon electrode (SPCE) using chitosan as cross-linked agent for 5-HT sensing studies; conducted through cyclic voltammetry (CV) and square wave voltammetry (SWV) measurements. Among the various composites, ZCNT0.1 NCs based electrodes exhibit higher sensing activity towards 5-HT in accordance to its higher surface area, lower particle size and lower charge transfer resistance. SWV measurements provide a wide linear response range (7.5–300 μM); lower limit of detection (0.66 μM), excellent limit of quantification (2.19 μM) and good reproducibility to ZCNT 0.1 NCs as compared to others for 5-HT sensing studies.

scholarly journals One-Step Fabrication of Stimuli-Responsive Chitosan-Platinum Brushes for Listeria monocytogenes Detection

Biosensors ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 511
Author(s):  
Daniela A. Oliveira ◽  
Suleiman Althawab ◽  
Eric S. McLamore ◽  
Carmen L. Gomes
Keyword(s):  
Listeria Monocytogenes ◽  
Surface Area ◽  
Limit Of Detection ◽  
Food Product ◽  
Critical Issue ◽  
Label Free ◽  
Stimuli Responsive ◽  
Chicken Broth ◽  
One Step ◽  
Electroactive Surface Area

Bacterial contamination in food-processing facilities is a critical issue that leads to outbreaks compromising the integrity of the food supply and public health. We developed a label-free and rapid electrochemical biosensor for Listeria monocytogenes detection using a new one-step simultaneous sonoelectrodeposition of platinum and chitosan (CHI/Pt) to create a biomimetic nanostructure that actuates under pH changes. The XPS analysis shows the effective co-deposition of chitosan and platinum on the electrode surface. This deposition was optimized to enhance the electroactive surface area by 11 times compared with a bare platinum–iridium electrode (p < 0.05). Electrochemical behavior during chitosan actuation (pH-stimulated osmotic swelling) was characterized with three different redox probes (positive, neutral, and negative charge) above and below the isoelectric point of chitosan. These results showed that using a negatively charged redox probe led to the highest electroactive surface area, corroborating previous studies of stimulus–response polymers on metal electrodes. Following this material characterization, CHI/Pt brushes were functionalized with aptamers selective for L. monocytogenes capture. These aptasensors were functional at concentrations up to 106 CFU/mL with no preconcentration nor extraneous reagent addition. Selectivity was assessed in the presence of other Gram-positive bacteria (Staphylococcus aureus) and with a food product (chicken broth). Actuation led to improved L. monocytogenes detection with a low limit of detection (33 CFU/10 mL in chicken broth). The aptasensor developed herein offers a simple fabrication procedure with only one-step deposition followed by functionalization and rapid L. monocytogenes detection, with 15 min bacteria capture and 2 min sensing.

scholarly journals Electrochemical nano-roughening of gold microstructured electrodes for the enhanced detection of copper and glucose

2021 ◽  
Author(s):  
Eduardo Gonzalez Martinez ◽  
Sokunthearath (Kevin) Saem ◽  
Nadine Beganovic ◽  
Jose Moran-Mirabal
Keyword(s):  
Surface Area ◽  
Limit Of Detection ◽  
Film Surface ◽  
High Sensitivity ◽  
Cost Effective ◽  
Progressive Increase ◽  
Gold Electrodes ◽  
Limit Of Quantification ◽  
Thin Film Surface ◽  
Electroactive Surface Area

One of the main challenges for electrochemical sensor miniaturization is the fabrication of electrodes with a smaller footprint, while maintaining, or even increasing, their sensitivity for the targeted application. Our research group has previously demonstrated the enhancement of the electroactive surface area of gold electrodes up to 6-fold, relative to planar gold electrodes with the same footprint, through the generation of a wrinkled thin film surface via thermal shrinking. In this work, the electroactive surface area of wrinkled gold electrodes was further enhanced up to 5-fold (30-fold over flat electrodes) using a chronoamperometric pulsing technique. Scanning electron microscopy images showed progressive increase of surface roughness in response to an increasing number of applied pulses. The resulting nanoroughened electrodes present several advantages in addition to the enhanced electroactive surface area. These electrodes offer superior fouling resistance compared to that of wrinkled and flat electrodes when submerged in a solution containing bovine serum albumin at high concentrations. Cyclic voltammetry data also revealed greater sensitivity of nanoroughened electrodes toward anodic copper stripping, where the limit of quantification of copper by the nano-roughened electrodes was 0.3 ppm. Nano-roughened electrodes also allowed the highly sensitive enzyme-free detection of glucose through chronoamperometry, with a limit of detection of 0.5 mM, whereas planar electrodes did not demonstrate any ability to oxidize glucose. We foresee that this methodology to fabricate nanostructured electrodes will accelerate the development of simple, cost-effective and high sensitivity electrochemical platforms.

scholarly journals THE INTERACTION OF Co2+-AMMONIA MODELLING: THE COMPARATIVE STUDY BETWEEN AB INITIO AND ELECTRON CORRELATION METHODS

2010 ◽  
Vol 2 (2) ◽  
pp. 67-73
Author(s):  
Harno Dwi Pranowo ◽  
Foliatini Foliatini ◽  
Karna Wijaya
Keyword(s):  
Charge Transfer ◽  
Comparative Study ◽  
Electron Correlation ◽  
Transfer Effect ◽  
Basis Set ◽  
Basis Sets ◽  
Complex Energy ◽  
Hartree Fock ◽  
Correlation Methods ◽  
The Comparative Study

Research on comparison between Hartree-Fock method and electron correlation methods as well as the effect of size of basis sets on representing interaction of Co2+-NH3 observed from complex energy parameters and optimum geometric parameters have been carried out.The first step is screening basis sets based on charge transfer effect and BSSE value. The selected basis set does not yield charge transfer at 1,4 Å  

Pandhawa Gubah sebagai Representasi Interaksi Metafisik Manusia Jawa dan Perbandingannya dengan Cheritera Pandawa Lima

Manuskripta ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 67
Author(s):  
Novarina Novarina
Keyword(s):  
Comparative Study ◽  
Literary Theory ◽  
Research Method ◽  
Descriptive Analysis ◽  
Literary Study ◽  
Analysis Method ◽  
Research Objects ◽  
Similarities And Differences ◽  
The Difference ◽  
The Comparative Study

Abstract: This research is a comparative literary study that uses Malay and Javanese versions of Mahabarata text sources. The research objects used were the text edition of Pandhawa Gubah (PG) by Sudibjo Z. Hadisutjipto and the text of Cheritera Pandawa Lima (CPL) by Khalid Hussain. The research method used is descriptive-analysis method. In the comparative study used a comparative literary theory proposed by Endraswara (2011). The results of the text comparison reveal the similarities and differences in the image of Bima figures in the Javanese and Malay versions. The equation as a whole is that both texts contain the same heroic storyline and heroic character, Bima. In addition, Indian influence is still evident in the two texts seen from the nuances of Hinduism that exist in both texts. While the difference is seen in the events that accompany Bima's struggle in achieving his victory. Based on these similarities and differences, it can be seen that the authors attempt to represent the concept of metaphysical interactions vertically and horizontally expressed through PG text. --- Abstrak: Penelitian ini adalah satu kajian sastra bandingan yang menggunakan sumber teks Mahabarata versi Melayu dan Jawa. Objek penelitian yang digunakan adalah edisi teks Pandhawa Gubah (PG) karya Sudibjo Z. Hadisutjipto dan teks Cheritera Pandawa Lima (CPL) karya Khalid Hussain. Metode penelitian yang digunakan adalah metode deskriptif-analisis. Dalam telaah perbandingan digunakan teori sastra bandingan yang dikemukakan Endraswara (2011). Hasil perbandingan teks mengungkapkan adanya persamaan dan perbedaan citra tokoh Bima dalam versi Jawa maupun versi Melayu. Persamaan secara keseluruhan adalah kedua teks tersebut mengandung alur cerita kepahlawanan dan tokoh pahlawan yang sama yaitu Bima. Selain itu, pengaruh India masih tampak dalam kedua teks tersebut dilihat dari nuansa Hinduisme yang ada dalam kedua teks. Sementara perbedaannya tampak pada peristiwa-peristiwa yang menyertai perjuangan Bima dalam mencapai kemenangannya. Berdasarkan persamaan dan perbedaan tersebut tampak adanya upaya penulis untuk merepresentasikan konsep interaksi metafisik secara vertikal dan horizontal yang diungkapkan melalui teks PG.

Auslandswissenschaft und kontrastive Kulturkomparatistik

2008 ◽  
Vol 2008 (1) ◽  
pp. 37-44
Author(s):  
Teruaki Takahashi
Keyword(s):  
Comparative Study ◽  
Intercultural Communication ◽  
Cultural Comparison ◽  
Intercultural Understanding ◽  
The Comparative Study

In the context of the controversies surrounding »globalisation« and In the context of the controversies surrounding »globalisation« and »multiculturality« the comparative study of cultures has the task of aiding intercultural communication and of contributing to the success of intercultural understanding. The model of contrastive cultural comparison discussed here is claimed to have applacibility to every possible study of other countries (»Auslandswissenschaft«) and to be able to provide the Geisteswissenschaften with an intercultural orientation.

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