scholarly journals Remnant photosynthetic pigments in tea dregs: identification, composition, and potential use as antibacterial photosensitizer

10.5219/1651 ◽  
2021 ◽  
Vol 15 ◽  
pp. 835-845
Author(s):  
Renny Indrawati ◽  
Elok Zubaidah ◽  
Aji Sutrisno ◽  
Leenawaty Limantara ◽  
Tatas Hardo Panintingjati Brotosudarmo
Keyword(s):  
Photosynthetic Pigments ◽  
High Performance ◽  
Light Emitting Diode ◽  
Spectral Characteristics ◽  
Red Light ◽  
Three Dimensional ◽  
Array Detector ◽  
Pheophytin A ◽  
Log Reduction ◽  
Potential Use

The production of tea dregs is continually increasing along with the growth of people's interest in ready-to-drink beverages. However, the recent development of research on the use of tea dregs is still very limited. The present study was aimed to identify the remnant photosynthetic pigments in tea dregs, determine their composition, and evaluate their potential use as natural antibacterial agents based on light-induced reaction (photosensitization). The tea dregs from six commercial teas, consisting of green and black teas, were analyzed using high-performance liquid chromatography (HPLC) with a photodiode array detector, and the spectroscopic data were analyzed from 350 to 700 nm. Pigment identification was performed based on spectral characteristics, and pigment composition in the extracts from the dregs was determined by a three-dimensional multi-chromatogram analysis method. The dominant pigment fractions in both tea types were pheophytin a and its isomers, as well as pheophytin b. Although the dregs of black teas generally contain fewer remnant pigments, they possess residual chlorophyll b, which is not found in the dregs of green teas. In thirty-minutes illumination under 50 W red light-emitting diode, the presence of pigments from tea dregs caused up to 0.87 and 0.35 log reduction of Staphylococcus aureus and Escherichia coli, respectively. The disparity of pigments composition among tea types does not strongly influence their photosensitization activity against both bacteria. Hence, upon further application, the amount of total remnant pigments in the dregs could be taken as substantial consideration instead of tea types.

A flexible, lightweight and stretchable all-solid-state supercapacitor based on warp-knitted stainless-steel mesh for wearable electronics

2022 ◽  
pp. 004051752110698
Author(s):  
Chuanli Su ◽  
Guangwei Shao ◽  
Qinghua Yu ◽  
Yaoli Huang ◽  
Jinhua Jiang ◽  
...  
Keyword(s):  
Stainless Steel ◽  
High Performance ◽  
Light Emitting Diode ◽  
Low Cost ◽  
Three Dimensional ◽  
Rate Capability ◽  
Cycling Stability ◽  
Wearable Electronics ◽  
Light Emitting ◽  
Dimensional Network

Highly conductive, flexible, stretchable and lightweight electrode substrates are essential to meet the future demand on supercapacitors for wearable electronics. However, it is difficult to achieve the above characteristics simultaneously. In this study, ultrafine stainless-steel fibers (with a diameter of ≈30 μm) are knitted into stainless-steel meshes (SSMs) with a diamond structure for the fabrication of textile stretchable electrodes and current collectors. The electrodes are fabricated by utilizing an electrodeposited three-dimensional network graphene framework and poly(3,4-ethylenedioxythiophene) (PEDOT) coating on the SSM substrates via a two-step electrodeposition process, which show a specific capacitance of 77.09 F g−1 (0.14 A g−1) and superb cycling stability (91% capacitance retention after 5000 cycles). Furthermore, the assembled flexible stretchable supercapacitor based on the PEDOT/reduced graphene oxide (RGO)@SSM electrodes exhibits an areal capacitance (53 mF cm−2 at 0.1 mA cm−2), a good cycling stability (≈73% capacitance retention after 5000 cycles), rate capability (36 mF cm−2 at 5 mA cm−2), stretchable stability (≈78% capacitance retention at 10% strain for 500 stretching cycles) and outstanding flexibility and stability under various bending deformations. The assembled supercapacitors can illuminate a thermometer and a light-emitting diode, demonstrating their potential application as stretchable supercapacitors. This simple and low-cost method developed for fabricating lightweight, stretchable and stable high-performance supercapacitors offers new opportunities for future stretchable electronic devices.

scholarly journals DEVELOPMENT OF METHODS OF PRE-COLUMNAR DERIVATIZATION OF GLUTATHIONES RECOVERED BY 4-METHOXY-2-NITROPHENYLISOTHIOTOCIONATE FOR DETERMINATION BY METHOD OF HIGH-EFFECTIVE LIQUID CHROMATOGRAPHY

2018 ◽  
Vol 6 (3) ◽  
pp. 229-240
Author(s):  
K. A. Alexeeva ◽  
D. I. Pisarev ◽  
O. O. Novikov ◽  
A. Yu. Malyutina
Keyword(s):  
High Performance ◽  
Uv Light ◽  
Heart Diseases ◽  
Spectral Characteristics ◽  
Analytical Signal ◽  
Direct Analysis ◽  
Reversed Phase ◽  
Array Detector ◽  
Rp Hplc

Nowadays the pharmacological role of glutathione in the therapy of carcinogenesis, neurodegenerative and ocular diseases, heart diseases, the immune system and aging of the organism is being actively investigated. Therefore, for the development of pharmaceutical medical forms on its basis, it is necessary to create an optimal analytical base. The aim of this study is to develop a methodology for the analysis of glutathione recovered by pre-columnar derivatization of 4-methoxy-2-nitrophenyl isothiocyanate. Materials and methods. Since glutathione does not have the necessary spectral characteristics for its direct analysis, a methodology for the determination of glutathione with the use of pre-columnar derivatization of 4-methoxy-2-nitrophenyl-isothiocyanate by reversed-phase high-performance chromatography (RP HPLC) has been developed on that basis. Detection of the resulting derivative has been carried out by absorption in UV light using a diode array detector. Results and discussion. In the course of the experiment described, chromatograms of a glulathione derivative with 4-methoxy-2-nitrophenyl isothiocyanate were obtained. This technique was also evaluated for the possibility of quantitative determination of glutathione. The sensitivity of the methods was 0.01% or 3.1*10-1 mol. The linear relationship between the analytical signal (peak area) and concentration was observed within the range of 0.01–0.08% and the correlation coefficient of 0.995. Conclusion. In the course of the studies, a methodology for the determination of glutathione has been developed with the use of pre-columnarderivatization of 4-methoxy-2-nitrophenyl-isothiocyanate by RP HPLC. In this case, the derivative is formed with the retention time of 22.3 minutes and the absorption maximum of 398 nm. This method also allows estimating the quantitative content of the object under study.

scholarly journals Light Energy Dose and Photosensitizer Concentration Are Determinants of Effective Photo-Killing against Caries-Related Biofilms

2020 ◽  
Vol 21 (20) ◽  
pp. 7612
Author(s):  
Abdulrahman A. Balhaddad ◽  
Mohammed S. AlQranei ◽  
Maria S. Ibrahim ◽  
Michael D. Weir ◽  
Frederico C. Martinho ◽  
...  
Keyword(s):  
Light Emitting Diode ◽  
Red Light ◽  
In Vitro Study ◽  
Disease Recurrence ◽  
Light Energy ◽  
Chemical Components ◽  
Biofilm Inhibition ◽  
Log Reduction ◽  
Energy Dose

Caries-related biofilms and associated complications are significant threats in dentistry, especially when biofilms grow over dental restorations. The inhibition of cariogenic biofilm associated with the onset of carious lesions is crucial for preventing disease recurrence after treatment. This in vitro study defined optimized parameters for using a photosensitizer, toluidine blue O (TBO), activated via a red light-emitting diode (LED)-based wireless device to control the growth of cariogenic biofilms. The effect of TBO concentrations (50, 100, 150, and 200 μg/mL) exposed to light or incubated in the dark was investigated in successive cytotoxicity assays. Then, a mature Streptococcus mutans biofilm model under sucrose challenge was treated with different TBO concentrations (50, 100, and 150 μg/mL), different light energy doses (36, 108, and 180 J/cm2), and different incubation times before irradiation (1, 3, and 5 min). The untreated biofilm, irradiation with no TBO, and TBO incubation with no activation represented the controls. After treatments, biofilms were analyzed via S. mutans colony-forming units (CFUs) and live/dead assay. The percentage of cell viability was within the normal range compared to the control when 50 and 100 μg/mL of TBO were used. Increasing the TBO concentration and energy dose was associated with biofilm inhibition (p < 0.001), while increasing incubation time did not contribute to bacterial elimination (p > 0.05). Irradiating the S. mutans biofilm via 100 μg/mL of TBO and ≈180 J/cm2 energy dose resulted in ≈3-log reduction and a higher amount of dead/compromised S. mutans colonies in live/dead assay compared to the control (p < 0.001). The light energy dose and TBO concentration optimized the bacterial elimination of S. mutans biofilms. These results provide a perspective on the determining parameters for highly effective photo-killing of caries-related biofilms and display the limitations imposed by the toxicity of the antibacterial photodynamic therapy’s chemical components. Future studies should support investigations on new approaches to improve or overcome the constraints of opportunities offered by photodynamic inactivation of caries-related biofilms.

Improved 3-D reconstruction using stereo computer graphics and multiple tilt EM images

1995 ◽  
Vol 53 ◽  
pp. 630-631
Author(s):  
Lee D. Peachey ◽  
Lou Fodor ◽  
John C. Haselgrove ◽  
Stanley M. Dunn ◽  
Junqing Huang
Keyword(s):  
Computer Graphics ◽  
High Performance ◽  
Transverse Section ◽  
Three Dimensional ◽  
Stereo Pair ◽  
3D Reconstructions ◽  
Video Cameras ◽  
Biological Objects ◽  
Microscope Images ◽  
High Performance Computer

Stereo pairs of electron microscope images provide valuable visual impressions of the three-dimensional nature of specimens, including biological objects. Beyond this one seeks quantitatively accurate models and measurements of the three dimensional positions and sizes of structures in the specimen. In our laboratory, we have sought to combine high resolution video cameras with high performance computer graphics systems to improve both the ease of building 3D reconstructions and the accuracy of 3D measurements, by using multiple tilt images of the same specimen tilted over a wider range of angles than can be viewed stereoscopically. Ultimately we also wish to automate the reconstruction and measurement process, and have initiated work in that direction.Figure 1 is a stereo pair of 400 kV images from a 1 micrometer thick transverse section of frog skeletal muscle stained with the Golgi stain. This stain selectively increases the density of the transverse tubular network in these muscle cells, and it is this network that we reconstruct in this example.

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