1IntroductionDetermination of glucose is very important, especially in the fields of healthcare,c linical, food and beverage industries [1][2].I nf ood and beverage industries,t he determination of glucosei sr equired for qualityc ontrol and fermentation processes. [ 3].I nt he clinicalf ield, glucose determinationi si mportant because high glucose levels can indicated iabetes mellitus,i nsulin deficiency and hyperglycemia [4][5].N ormal concentrations of glucose are 3.5-5.5 mM in whole blood, 2.5-5.3 mM in serum, and 0.1-5.3 mM in urine [6].A lthough conventional methodo f high performancel iquid chromatography (HPLC) coupled with enzyme assays have been reported for the glucose determination, they require many steps while consuming of time,r eagents and samples.T herefore, as imple,f ast and low cost method is still needed to develop for the determinationo fglucose.Here,s everal paper-based analytical devices were developed and used as ad iagnosticd evices.S ince 2007 when Whitesides and co-workers demonstrated microfluidic devices madef rom photoresist-patterned paper or mPADs,e xtensive efforts have been placed on developing low-cost sensors with usingn aked eyesc olorimetricd etection [7][8][9].M oreover, other detectiont echniques such as absorption spectroscopy [ 10],c hemiluminescence [11][12],a nd electrochemistry [13][14][15][16][17][18]h ave been proposed to provideb etter sensitivity and selectivity.E lectrochemical detection is of particular interest when combined with a mPA Dd ue to its low cost,p ortability,h igh accuracya t low analytec oncentrations,l ow sample consumption, and the ability for miniaturization.Screen-printed carbon electrodes (SPCEs) have many advantages for mPA Ds due to their low cost, ease of preparation, flexible design, and ease of modificationb yv arious chemicals for sensing applications [19][20][21][22].O nt he otherhand, abare SPCE lacks its sensitivity in trace analysis wheni ti sc ompared with am odified electrode. Electrodem odification can also reduce the effect of interferences at high over-potentials [23][24].H ence,t he type of modifying chemicals is important to investigate for each analysis.I nt his work, cellulose was chosena samodifying chemical mixed with carboni nk, which was used for fabrication of SPCEs.D ue to an etwork structure and al arge number of porous, celluloseh as al arge surface area that is suitable for improvemento fs ensitivity of electrochemicald etection.Redox mediators are interesting for electrode modification in glucose biosensors because they can enhance the Abstract:T he present work describes the fabrication of paper-based analytical devices (mPA Ds) by immobilization of glucose oxidase onto the screen printed carbon electrodes (SPCEs)f or the electrochemicalg lucose detection. Thes ensitivity towards glucosew as improved by using aS PCE prepared from homemade carboni nk mixed with cellulose acetate. In addition, 4-aminophenylboronic acid (4-APBA) was used as ar edox mediator giving al ower detectionp otentialf or improvement selectivi...

ZnO nanoparticles (NPs) were comparatively synthesized via precipitation and combustion techniques. The ZnO NPs synthesized via precipitation and combustion exhibited similar polycrystalline hexagonal wurtzite structures. The large crystal sizes of ZnO NPs were obtained from the ZnO precipitation in comparison with those from the ZnO combustion, while the particle sizes were in the same range. The functional analysis implied that the ZnO structures had surface defects. Moreover, absorbance measurement showed the same absorbance range in ultraviolet light. In the photocatalytic degradation of methylene blue, ZnO precipitation exhibited higher degradation performance than ZnO combustion. This was attributed to the larger crystal sizes of ZnO NPs, which provided an enduring carrier movement at semiconductor surfaces and reduced electron-hole recombination. Thus, the crystallinity of ZnO NPs can be considered an important factor in photocatalytic activity. Furthermore, precipitation is an interesting synthesizing method for preparing ZnO NPs with large crystal sizes.

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In this work, Y-doped ZnO nanoparticles were precipitately synthesized for various yttrium molar percentage values ranging from 0 to 5%, and then utilized as photocatalysts to demonstrate methylene blue degradation. Morphology shows that the particle size of pure ZnO is 113.7733.26 nm, which is reduced to the minimum value less than one-third for the Y-doped ZnO samples. As a result, surface-to-volume ratios of Y-doped ZnO samples have successfully increased due to their decreased size. This decrease in particle size is consistent with the small crystalline size, primarily due to low crystallization in the presence of yttrium doping. However, the expansion of the crystal structure is observed. Chemical surface structures point to the major vibration of ZnO. However, some carbon-relating groups remain to appear. Optical property reveals similar trends for all Y-doped ZnO samples. The estimated band gap energy (Eg) was reduced to the minimum value for the 4 mol% condition. For use as a photocatalyst, the appropriate Y-doped ZnO for 4 mol% yttrium doping presents the maximum degradation efficiency of 61.19%. The improvement in photocatalytic degradation is caused by the synergy of decreased particle size and reduced Eg. Therefore, yttrium plays a role to decrease particle size and reduce Eg of Y-doped ZnO materials, thus leading to enhance photocatalytic performance.