In this paper, the A. fumigatus α-amylase had been immobilized onto zeolite/chitosan hybrid to improve its thermal-stabilization for industrial needs. The methods applied enzyme production, isolation, partial purification, immobilization, and characterization. The optimum temperatures of the native and immobilized enzymes were 50 and 55˚C, respectively. The native enzyme has KM of 3.478 ± 0.271 mg mL-1 substrate and Vmax of 2.211± 0.096 µmole mL-1 min-1, while the immobilized enzyme has KM value of 12.051 ± 4.949 mg mL-1 substrate and Vmax of 1.602 ± 0.576 µmole mL-1 min-1. The residual activity of the immobilized enzyme retained up 10.97% after fifth reuse cycles. The native enzyme has ΔGi of 104.35 ± 1.09 kJ mole-1 and t½ of 38.75 ± 1.53 min, while the immobilized enzyme has ΔGi of 108.03 ± 0.05 kJ mole-1 and t½ of 180.03 ± 3.31 min. According to the increase in half-life (t½), stability improvement of the A. fumigatusα-amylase was 4.65 times greater than the native enzyme. Thus, the zeolite/chitosan hybrid is used as a new supporting matrix for further enzyme immobilization to stabilize the enzymes. Doi: 10.28991/ESJ-2022-06-03-06 Full Text: PDF

In this research, a control system in the form of a syringe pump has been developed to control the volume and flow rate of a liquid or a solution. The syringe pump is fabricated by controlling the speed and pulse width modulation (PWM) of stepper motors based on the Arduino Uno microcontroller board. The tools used are a stepper motor as a syringe driver, the Arduino Uno as a controller, a four-digit seven-segment display and a keypad matrix as an input interface. The syringe pump works by pushing the injection pump whose speed has been adjusted to the flow rate. The speed of the flow rate and volume are obtained by setting the delay time of the stepper motor using PWM pins from the Arduino Uno. The syringe pump is observed to work in the flow rate range of 0.10-12.00 ml h -1 . The system can be applied to medical settings as the control of volume and flow rate of drug fluids as well as with nanofibres using electrospinning technique.

In medicinal field, delivery agent is a very important substance to improve the efficiency of drug used by improving the stability and preventing the degradation of drug during the medical treatment. Due to these important roles of the drug delivery agent, the search of effective agent is continuously in progress. In this respect, this current research was carried out to synthesize cellulose–polylactic acid (cellulose-PLA), as a potential delivery agent of rifampicin for the curing of tuberculosis. Cellulose was isolated from cassava bagasse, while PLA was obtained from commercial supplier. The two raw materials were used to synthesize cellulose–PLA in 3.5% HCl as solvent under magnetic stirring. The product obtained was then characterized by Fourier-Transform Infrared spectroscopy (FTIR), Particle-Size Analysis (PSA), and Scanning Electron Microscopy (SEM). The FT-IR result showed the presence of hydroxy (3446 to 3429 cm−1) and carbonyl (1757 to 1759 cm−1), confirming the formation new bond between cellulose and PLA. The PSA characterization displays a particle-sizes of PLA are in the range of 960–92780 nm, while cellulose–PLA are in the range of 100–17730 nm demonstrating that cellulose-PLA combined to form more compact structures. The results of SEM analysis indicate the distinct feature of cellulose-PLA, and combination of the features in the cellulose and PLA image. The results of the dissolution test carried out two different concentrations of rifampicin revealed that the optimum dissolution (8.42%) was achieved with cellulose–PLA of 0.3%, dissolution time of 12 h, and pH of 7.4.

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Senyawa organotimah(IV) karboksilat dan semua turunannya menunjukan aktivitas biologi sangat kuat dan dikenal memiliki aktivitas penghambatan yang tinggi bahkan pada konsentrasi yang sangat rendah sehingga golongan senyawa ini sangat menarik untuk terus dipelajari. Melanjutkan keberhasilan dalam sintesis senyawa organotimah(IV) karboksilat pada beberapa penelitian sebelumnya, dalam makalah ini kami laporkan hasil sintesis senyawa difeniltimah(IV) di-(3-hidroksibenzoat) dan trifeniltimah(IV) 3-hidroksibenzoat dari bahan awal senyawa difeniltimah(IV) oksida dan trifeniltimah(IV) hidroksida dengan ligan asam 3-hidroksibenzoat . Senyawa hasil sintesis dikarakterisasi dengan beberapa teknik spektroskopi dan mikroanalisis unsur. Hasil analisis menunjukan kedua senyawa hasil sintesis memiliki kemurnian yang baik dengan waktu refluks 4 jam dan nilai persen rendemen berturut-turut 92,66% dan 88,60%.