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Abstrak :
ABSTRACT
In order to shorten the measurement time of biochemical oxygen demand (BOD), a BOD sensor based on yeast metabolism was developed. Local yeast, Indonesian Origin, Candida fukuyamaensis UICC Y-247, was used as a transducer. The yeast was immobilized as a thin film in ag arose matrix with the auxiliary of Nafion® acting as the membrane for ion exchange process. The film was then attached to gold-modified glassy carbons and used as transducer on the working electrodes. The measurements were conducted by observing the depletion of glucose concentration using multipulse amperometric method and then converte d to BOD values. Optimum condition was observed in a waiting measurement time of 30 min at an applied potential of 450 mV (vs. Ag/AgCl). Linearity was shown in glucose concentration range of 0.1?0.5 mM, which was equivalent to BOD concentration range of 10?50 mg/L. A detection limit of 1.13 mg/L BOD could be achieved. Good repeatability was shown by a relative standard deviation (RSD) of 2.7% (n = 15). However, decreasing current response of ~50% was found after 3 days. Comparing to the conventional BOD measurement, this BOD sensor can be used as an alternative method for BOD measurements.

Abstrak :
Pengembangan Strip Test Immunokromatografi untuk Pendeteksi Melamine Secara Selektif dan Kuantitatif. 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 100 μL 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.

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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 100 μL 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.

Abstrak :
Two flavonoid compounds, 5,7,3?,4?-tetrahydroxy-6-geranylflavonol (1) and kaempferol 7-O-β-glucose (2) have been isolated from the leaves of Macaranga hispida (Blume), Mull.Arg. Isolation and purification were conducted by chromatography methods and chemical structure characterization was carried out by spectroscopic methods. The 5,7,3?,4?-tetrahydrxyi-6-geranyl flavonol (1) and kaempferol 7-O-glucose (2) had moderate cytotoxic activity against murine leukemia P-388 cell lines with IC50 value of 0.22 and 101.5 μg/mL, respectively. The IC50 for antioxidant activities of (1) and (2) were 2.83 and 13.95 μg/mL, respectively. The LC50 of (1) and (2) from BSLT were 350 and >1000 μg/mL, respectively.

Identifikasi dan Studi Bioaktifitas Senyawa Flavonoid dari Macaranga hispida (Blume) Mull.Arg. Dua senyawa flavonoid, 5,7,3?,4?-tetrahidroksi-6-geranilflavonol (1) dan kaemferol 7-O-β-glukosa (2) telah diisolasi dari daun Macaranga hispida (Blume) Mull. Arg. Isolasi dan pemurnian dilakukan dengan metode kromatografi dan karakterisasi struktur kimia dilakukan dengan metode spektroskopi. 5,7,3', 4'-tetrahidroksi-6-geranil flavonol (1) kaemferol 7-Oglukosa (2) memiliki aktivitas sitotoksik sel murine leukemia P-388 dengan nilai IC50 masing-masing 0,22 dan 101,5 μg/mL. Aktivitas antioksidan (1) dan (2) dinyatakan dengan nilai IC50 masing-masing sebesar 2,83 dan 13,95 μg/mL. Nilai LC50 dengan uji BSLT (1) dan (2) masing-masing 350 dan >1000 μg/mL.

Abstrak :
Mannan is an abundant polysaccharide that can be found in konjac (Amorphophallus sp.). Mannan can be enzymatically hydrolyzed using mannanase to produce manno-oligosaccharides which can be used as a prebiotic. The aims of this research are to determine the production time of mannanase from Streptomyces lipmanii, perform enzyme characterization, optimize the hydrolysis time, and characterize the hydrolysis product. A qualitative assay using the indicator Congo red showed that S. lipmanii generated a clear zone, indicating that S. lipmanii produced mannanase in konjac medium and possessed mannanolytic activity. Enzyme activity was determined through reducing sugar measurement using the dinitrosalycylic acid method, and optimum enzyme production was achieved at the second day of culture. Characterization of the enzyme showed that hydrolysis was optimum at pH 7 and at a temperature of 50 oC. The reducing sugar content was increased by an increasing the hydrolysis time, and reached an optimum time at 2 h. The degree of polymerization value of three was achieved after 2 h hydrolysis of mannan from konjac, indicating the formation of oligosaccharides. Analysis by thin layer chromatography using butanol, acetic acid, and water in a ratio of 2:1:1 as eluent showed the presence of compounds with a retention time between those of mannose and mannotetrose. Confirmation was also performed by HPLC, based on the retention time.

Hidrolisis Enzimatik Mannan dari Umbi Porang (Amorphophallus sp.) menggunakan Enzim Mannanase dari Streptomyces lipmanii untuk Pembuatan Manno-oligosakarida. Mannan adalah polisakarida yang melimpah yang dapat ditemukan pada umbi porang (Amorphophallus sp.). Mannan dapat dihidrolisis secara enzimatik menggunakan mannanase untuk memproduksi manno-oligosakarida, yang dapat digunakan sebagai prebiotik. Tujuan dari penelitian ini adalah menentukan waktu produksi mannanase dari Streptomyces lipmanii, karakterisasi enzim, optimasi waktu hidrolisis, dan karakterisasi produk hidrolisis. Uji kualitatif dengan menggunakan Congo red, menunjukkan bahwa S. lipmanii menghasilkan zona bening, yang menunjukkan bahwa S. lipmanii menghasilkan mannanase dalam medium umbi porang dan memiliki aktivitas mannanolitik. Aktivitas enzim ditentukan melalui pengukuran gula pereduksi menggunakan metode asam dinitrosalisilat, dan produksi optimum enzim dicapai pada kultur hari kedua. Karakterisasi enzim menunjukkan bahwa reaksi hidrolisis optimum pada pH 7 dan suhu 50 °C. Kadar gula pereduksi meningkat dengan bertambahnya waktu hidrolisis, dan mencapai optimum pada jam kedua. Derajat polimerisasi senilai 3 telah tercapai setelah hidrolisis mannan selama 2 jam yang menunjukkan terbentuknya oligosakarida. Analisis dengan kromatografi lapis tipis menggunakan eluen butanol, asam asetat, dan air dengan rasio 2:1:1, menunjukkan adanya senyawa yang memiliki faktor retensi antara mannosa dan mannotetrosa. Hasil tersebut juga dikonfirmasi dengan kromatografi cair kinerja tinggi, berdasarkan waktu retensi senyawa.