A comprehensive analysis of classification methods in gastrointestinal endoscopy imaging.

Gastrointestinal (GI) endoscopy has been an active field of research motivated by the large number of highly lethal GI cancers. Early GI cancer precursors are often missed during the endoscopic surveillance. The high missed rate of such abnormalities during endoscopy is thus a critical bottleneck. Lack of attentiveness due to tiring procedures, and requirement of training are few contributing factors. An automatic GI disease classification system can help reduce such risks by flagging suspicious frames and lesions. GI endoscopy consists of several multi-organ surveillance, therefore, there is need to develop methods that can generalize to various endoscopic findings. In this realm, we present a comprehensive analysis of the Medico GI challenges: Medical Multimedia Task at MediaEval 2017, Medico Multimedia Task at MediaEval 2018, and BioMedia ACM MM Grand Challenge 2019. These challenges are initiative to set-up a benchmark for different computer vision methods applied to the multi-class endoscopic images and promote to build new approaches that could reliably be used in clinics. We report the performance of 21 participating teams over a period of three consecutive years and provide a detailed analysis of the methods used by the participants, highlighting the challenges and shortcomings of the current approaches and dissect their credibility for the use in clinical settings. Our analysis revealed that the participants achieved an improvement on maximum Mathew correlation coefficient (MCC) from 82.68% in 2017 to 93.98% in 2018 and 95.20% in 2019 challenges, and a significant increase in computational speed over consecutive years.

Horseradish peroxidase-catalyzed polymerization of L-DOPA for mono-/bi-enzyme immobilization and amperometric biosensing of H2O2 and uric acid.

Horseradish peroxidase (HRP)-catalyzed polymerization of L-DOPA (vs. dopamine) in the presence of H2O2 (and uricase (UOx)) was exploited to immobilize mono-/bi-enzymes for hydroquinone-mediated amperometric biosensing of H2O2 and uric acid (UA). The relevant polymeric biocomposites (PBCs) were prepared in phosphate buffer solution containing HRP and L-DOPA (or plus UOx) after adding H2O2. The mono-/bi-enzyme amperometric biosensors were prepared simply by casting some of the PBCs on Au-plated Au (Au(plate)/Au) electrodes, followed by coating with an outer-layer chitosan (CS) film for each. UV-vis spectrophotometry, scanning electron microscopy, cyclic voltammetry and electrochemical impedance spectroscopy were used for film characterization and/or process monitoring. The HRP immobilized by enzyme catalysis well preserved its bioactivity, as confirmed by UV-vis spectrophotometry. Under optimized conditions, the monoenzyme CS/HRP-poly(L-DOPA) (PD)/Au(plate)/Au electrode potentiostated at -0.1V responded linearly to H2O2 concentration from 0.001 to 1.25mM with a sensitivity of 700µA mM(-1)cm(-2) and a limit of detection (LOD) of 0.1µM, and the bienzyme CS/UOx-HRP-PD/Au(plate)/Au electrode at -0.1V responded linearly to UA concentration from 0.001 to 0.4mM with a sensitivity of 349µA mM(-1)cm(-2) and a LOD of 0.1µM. The mono-/bi-enzyme biosensors based on biosynthesized PD performed better than many reported analogues and those based on similarly biosynthesized polydopamine.

An EQCM study on the interaction of heparin with the charge-transfer complex generated during o-tolidine electrooxidation: a biosensing mode with a dynamically renewed surface.

The electrooxidation of o-tolidine (oTD) was investigated via the electrochemical quartz crystal microbalance (EQCM) technique. The formation and breakage of the poorly soluble charge-transfer complex (CTC) occurred during the redox switching of oTD, and the CTC precipitation on and its removal from the electrode surface led to a V-shaped frequency response to the cyclic voltammetric switching of oTD. The V-shaped frequency response to the redox switching of the CTC/oTD "couple" and the electrode-collection efficiency of the CTC precipitate were notably enhanced by the introduction of sodium heparin due to the formation of the CTC-heparin adduct as reported here for the first time. FTIR and UV-Vis characterizations also supported the interaction between the CTC and heparin. The molar ratio of the positively charged CTC to negatively charged heparin of the adduct was estimated here to be between 31.5 and 36.5, being close to the anticipated value, 37.5, for the full electrical neutralization in the adduct. An EQCM-based biosensor featured by a dynamically renewed surface of the detection electrode was proposed for heparin assay, with a limit of detection of 18.5 nM (S/N=3) in pH 6.0 Britton-Robinson buffer solution containing a 10-fold diluted blood serum. This method is convenient in operation and highly free from the interference from coexisting substances including proteins. The new and intriguing biosensing concept based on the labile CTC-"target" adduct is featured by a dynamically renewable and regenerable surface of the detection electrode, and it is highly recommended for wide biosensing and electroanalytical applications.

Electrochemical quartz crystal impedance and fluorescence quenching studies on the binding of carbon nanotubes (CNTs)-adsorbed and solution rutin with hemoglobin.

Electrochemical quartz crystal impedance (QCI) technique was utilized to monitor in situ the adsorption of rutin (RT) onto a carbon nanotubes (CNTs)-modified gold electrode and to study the binding process of solution hemoglobin (Hb) to RT immobilized on the electrode. Time courses of the QCI parameters including crystal resonant frequency were simultaneously obtained during the RT adsorption and Hb-RT binding. In contrast to the negligible RT adsorption at a bare gold electrode, the modification by CNTs notably enhanced the amount of adsorption, and almost all of the adsorbed RT molecules were found to be electroactive. On the basis of the frequency response from the binding of adsorbed RT to solution Hb and the diminished electroactivity of adsorbed RT after the formation of the electrochemically inactive RT-Hb adduct, the average binding molar ratio of adsorbed RT to Hb was estimated to be 23.9:1, and the association constant (Ka) for the binding was estimated to be 2.87 x 106 (frequency) and 3.92 x 106 (charge) L mol-1, respectively. Comparable results were obtained from fluorescence quenching measurements in mixed solutions containing RT of fixed concentration and Hb of varying concentrations, demonstrating that the interfacial RT here behaved equivalently in the RT-Hb binding activity compared to that in solution. This work may have presented a new and general protocol involving CNTs to study many other electroactive natural antioxidants or drugs that are at the interface or in solution, their binding with proteins or other biomolecules, and changes of their antioxidant activity after the binding.