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Copyright of Makara Journal of Science is the property of Universitas Indonesia, Directorate of Research & Community Engagement and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

An immunochromatographic strip test based on the complex reaction of antigen-antibody (melamine-antimelamine) was developed for quantitative detection of melamine. Gold nanoparticles (AuNP) were used to form AuNP-labeled antibody, which then acted as a biosensor. Melamine quantification was performed by the determination of AuNP using anodic stripping voltammetry technique with a boron-doped diamond as the working electrode. With sample volume of 100μL and immunoreaction time of 7 min, the developed immunochromatographic strip test produced a linear calibration curve for melamine concentration range of 0-0.6 mg/L, with detection limit of 0.1 mg/L and RSD of ~5%. Furthermore, negative results were obtained for samples containing cyanuric acid and urea, indicating that the developed immunochromatographic strip test has potential for selective and quantitative detection of melamine. Strip test berbasis imunokromatografi berdasarkan reaksi pembentukan kompleks antigen-antibodi (melamin-antimelamin) dikembangkan untuk mendeteksi melamin secara kuantitatif. Nanopartikel emas (AuNP) digunakan sebagai label pada antibodi untuk membentuk antibodi berlabel AuNP yang kemudian berfungsi sebagai biosensor. Kuantifikasi melamin diperoleh dengan menentukan konsentrasi AuNP menggunakan teknik anodic stripping voltammetry. Boron-doped diamond digunakan sebagai elektroda kerja. Dengan volume sampel 100μL dan waktu imunoreaksi 7 menit, strip test menghasilkan kurva linier pada kisaran konsentrasi 0-0,6 mg/L dengan batas deteksi 0.1 mg/L dan RSD ~5%. Selain itu hasil negatif diperoleh ketika strip test diaplikasikan pada sampel yang mengandung asam sianurat dan urea, hal tersebut mengindikasikan bahwa strip test yang dikembangkan dapat digunakan sebagai pendeteksi melamin secara selektif dan kuantitatif. [ABSTRACT FROM AUTHOR]

This study presents the in vivo electrochemical monitoring of pH using boron doped diamond (BDD) microelectrode and silver needles for potential application in medical diagnosis. Accurate calibration curve for pH determination were obtained through in vitro electrochemical measurements. The increase induced in stomach pH by treatment with pantoprazole was used to demonstrate that it is possible to monitor the pH in vivo using the simple and noninvasive system proposed herein. Using the results of the in vivo and in vitro experiments, a quantitative analysis of the increase in stomach pH is also presented. It is proposed that the catheter-free pH monitoring system presented in this study could be potentially employed in any biological environment. [ABSTRACT FROM AUTHOR]

Abstract  Two novel types of photomagnetic hybrid ultrathin film (film A and B) of metal cyanides have been fabricated by means of the modified Langmuir–Blodgett method using a smectite clay mineral. Film A is composed of an amphiphilic azobenzene cation, a montmorillonite, and Prussian Blue in which photocontrol in the magnetization was realized by the photoisomerization of azobenzene chromophore. The observed photomagnetic efficiency was large (ca. 11%) due to the well-organized structure of the ultrathin film. Film B is composed of a quaternary ammonium salt, a montmorillonite, and Co–Fe Prussian Blue in which the photoinduced magnetization caused by the electron transfer exhibited an anisotropic response with regards to the direction of the applied magnetic field. This phenomenon is ascribed to the unique structure of Co–Fe Prussian Blue formed onto the clay layer. [ABSTRACT FROM AUTHOR]

A novel star-shaped high-spin Fe(III) tetranuclear cluster was unexpectedly obtained by the reaction of an [FeIII(phsal)2]- anion with an Fe(II) coordination cation (H2phsal: N-(2-hydroxyphenyl)salicylaldimine). Despite a star-shaped Fe(III) tetranuclear structure similar to reported Fe(III) single molecule magnets, the present compound exhibited a bulk antiferromagnetic transition at 0.6K due to a magnetic exchange coupling through intercluster π-stacking interactions. [ABSTRACT FROM AUTHOR]

A three-dimensional mixed-valence iron complex with NiAs-type topology, [(FeIII3O)FeII(TA)6(H2O)3]·(ClO4)2(NO3)(EtOH)(H2O)2 (1, HTA = tetrazole-1H-acetic acid), shows spin-crossover behavior that was characterized via variable-temperature crystal structures, Mössbauer spectra and magnetic susceptibilities, the pressure effects on the transition behavior were also studied. [ABSTRACT FROM AUTHOR]

Overuse of levofloxacin (LEV) is often associated with bacterial resistance and serious health problems, underscoring the need for reliable sensing and monitoring of LEV molecules. Therefore, this study aimed to investigate LEV using boron-doped diamond (BDD) and boron-doped diamond modified with MXene (Ti3C2TX) (BDD-MXene) electrode. The successful deposition of MXene on the BDD surface was confirmed using scanning electron microscope (SEM). Cyclic voltammetry (CV) and square wave voltammetry (SWV) methods were also applied to evaluate the electrochemical behavior. The results showed that both electrodes had a linear response in the range of 30-100 µM. The limit of detection (LOD) and limit of quantitation (LOQ) were found to be 1.0 X 10-6 M and 3.37 x 10-6 M for bare-BDD, while on BDD-MXene, the values were 3.90 x 10-7 M and 1.30 x 10-6 M, respectively. Furthermore, both electrodes showed good responses on selectivity tests with glucose and another fluoroquinolone antibiotic such as ciprofloxacin. The results also indicated good precision with %RSD less than 5%. In real sample applications using wastewater, bare-BDD and BDD-MXene produced excellent %recovery of 92.96% and 101.29%, respectively. [ABSTRACT FROM AUTHOR]

An electrochemical method was developed for biodiesel, i.e., fatty acid methyl ester (FAME), production. A two-compartment cell completed with a cation-exchange separating membrane was utilized to minimize recombination between protons and hydroxide or methoxide ions, which leads to the low product yield. In addition to the product yield increase, the method was found to reduce the requirement of organic salt to be only in the cathode chamber. Electrolysis at low voltage (4.6 V) resulting high product yield (ca. 94% in 2 h) at Pt as well as a boron-doped diamond (BDD) electrode as the cathode, suggested the system was free from the dependence on electrode types. [ABSTRACT FROM AUTHOR]

Nanosized ε-Fe2O3 crystals with a diameter below 20 nm were successfully prepared at 600 °C in a mesoporous silica matrix. The formation of the metastable iron oxide occurred through nanoscale segregation in an immiscible SiO2-Fe2O3 system having a mesoporous structure. The nanocrystals incorporated into ca. 50 nm-size particles of the mesoporous silica exhibited a coercive field up to 8 kOe. [ABSTRACT FROM AUTHOR]

An abstract of the article "Selective Detection of As(V) with High Sensitivity by As-deposited Boron-doped Diamond Electrodes," by Yasutaka Nagaoka and colleagues is presented.

CO2 electrochemical reduction (CO2ER) activity is known to be influenced by electrode materials. In this study, we report the fabrication of a copper-nickel-modified boron-doped diamond (CuNi-BDD) electrode using wet chemical seeding and electrodeposition. Annealing was performed to improve the stability of the modified electrode during electrolysis. Characterization of the modified BDD electrodes shows successful deposition without damage to the surface of the BDD support material. CO2ER was conducted with the CuNi-BDD electrode, which produces various important products including methanol, formic acid, CO, and CH4. Additionally, a different applied potential affected the product distribution. CO2ER was also conducted on the surfaces of Cu-BDD and Ni-BDD electrodes for comparison. [ABSTRACT FROM AUTHOR]

The article presents a study of the charge-spin conversion in metallic Rashba spin-orbit devices controlled by molecular self-assembly. It demonstrates how the magnetoresistance and voltage generation resulting from spin-charge conversion in metallic hererostructures can be manipulated through molecular engineering and through the cooperative molecular field effect.