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A novel highly sensitive and selective molecularly imprinted polymer (MIP) cryogel biosensor for determination of microalbumin in urine samples was fabricated. The MIP gel was prepared based on the graft copolymerization of acrylamide with N,N'-methylenebisacrylamide on chitosan using human serum albumin (HSA) as the template. The sub-zero polymerization allowed the solvent to form ice crystals and left a macroporous cryogel structure when it was thawed. After removing the template, the specific imprinted surface on cryogel pore walls was used to detect HSA via a redox mediator (ferrocene), entrapped in the cryogel, using differential pulse voltammetry (DPV). The electrochemical detection was improved by the presence of graphene that has been composited within the polymer. For determination of albumin, the fabricated MIP cryogel biosensor showed a high sensitivity with a wide linear range of 1.0 × 10(-4) to 1.0 × 10(1) mg L(-1) and a low limit of detection of 5.0 × 10(-5) mg L(-1) (S/N = 3). The sensor also provided a very good reusability, i.e., the sensitivity remained >90% after 9 cycles of binding-rewashing (18 analyses per cycle), while the sensitivity only decreased to 90% after 6 weeks of storage at room temperature. The biosensor also showed a good selectivity, both against bovine serum albumin (BSA) and some common possible interfering compounds normally present in urine (ascorbic acid, uric acid, urea, sodium, chloride, potassium and creatinine). The excellent performance of the biosensor was confirmed by analyzing microalbumin in urine samples, and results were in good agreement with those obtained by the standard immunoturbidimetric method (P > 0.05).

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One of the plants which are efficacious as antibacterial is the soursop leaves. Soursop leaves were extracted by maceration using n-hexane. The extract was evaporated using rotary evaporator. Soursop leaves extract was then formulated in a gel dosage form. This study aims toformulate hand sanitizer from soursop leaves extract based on Growing Minimum Inhibitory Concentrations (MIC) of n-hexaneextract of soursop leaves, and to know the evaluation result of gel dosage with the active substance of soursop leaves extract. Testing of physical properties of the gel includes organoleptic test, dispersive power test, homogeneity, pH, and consistency test. Antibacterial activity was tested by using a diffusion method. The evaluation of the gel showed SNI standards which wereable for topical use. The organoleptic test resultedthat the dosage is odorless, transparent and gel. Homogeneity test resulted that all gel dosage concentrations are homogenous. The pH tests at concentrations of 1, 5 and 10 ppm respectively are 5.38 to 6.22; 5.48 to 6.28; and from 5.29 to 5.90. The dispersive power test resulted for 6.47 to 7 cm; 6.20 to 6.87 cm; and 6.09 to 6.59 cm. The consistency test resulted that all gel dosages are consistent in gel form.Gel dosage with extract concentrations of 1, 5 and 10 ppm can inhibit the growth of bacteria P. acne with antibacterial activity of 3.53; 3.26 and 2.20 mm.

Enzyme immobilizations were widely used to increase their shelf life which is essential for the world’s industries. Therefore, amylase immobilized using Na-alginate as a matrix is necessary optimized and characterized. The parameters measured in the optimization of immobilization are the determination of the concentration of sodium alginate and contact time. Characterizations were conducted to determine the optimum concentration of substrate, the value Vmax, Michaelis-Menten constant (KM), pH, temperature, incubation time, and test reuse. The process of immobilized amylase activity test was performed in a continuous flow system using a reactor, and its sugar levels were determined using the Dinitro Salisilat Method (DNS). The results reveal that the immobilized amylase commercial has optimum concentration of Na-alginate of 5% (w/v) and contact time of 90 minutes with an immobilization efficiency value of 43.02%. Furthermore, the immobilized amylase has optimum activity at substrate concentrations of 3.5% (w/v), pH 4, incubation temperature of 40 °C, and a reaction time of 20 minutes with the value of the activity of 2760.4 U / mL. KM value of free amylase and immobilized amylase row are 0.18 mM and 0.15 mM, repectively. The value of KM immobilized amylase is smaller than the free enzyme. It proves that the immobilized amylase has a high affinity for the substrate. The immobilized amylase can be used up to 12 times with a value of the residual activity of 56.7%.

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