THE EFFICIENCY OF BIOSILICA FROM CYCLOTELLA STRIATA TBI AS A MATRIX FOR HUMAN SERUM ALBUMIN DEPLETION COLUMN

• Main Author: Tri Agustina, Henty
• Format: Theses
• Language: Indonesia
• Subjects: Kimia
• Online Access: https://digilib.itb.ac.id/gdl/view/72781
• Institution: Institut Teknologi Bandung

Several diseases can be detected through analysis of the content and levels of certain proteins in blood serum, for example disorder of kidney, liver, autoimmune, and cancer. However, the protein marker signal is relatively small compared to the albumin signal because albumin is present in a high concentration in the serum sample. Therefore, in order to detect the protein marker, it is necessary to deplete the serum sample or reduce its albumin content, using a depletion column. Several commercial column matrixes for depleting albumin are made from carbohydrates or silica resins. As an alternative to the depletion column, a natural material that can be a source of silica is diatom microalgae shells which are abundant in Indonesian waters. The diameter of diatom is about 10–15 µm and composed of hierarchical porous silica, large pores with hundreds of nanometers small pores up to 10 nm in size. The diatom shell is called biosilica because it is synthesized enzymatically by diatom organisms. Diatom biosilica can be purified from diatom cultures. Furthermore, pure biosilica can be modified and used for various applications, for example purification, catalysis, sensors, and biomaterials. Until now the development of biosilica diatoms from Indonesian waters, especially Cyclotella striata TBI, has not get into protein purification applications, especially in context of albumin depletion. In fact, diatom biosilica is a renewable material that can be produced sustainably and can be modified according to purification needs. Therefore, the aim of this study was to characterize the biosilica efficiency of C. striata TBI as a human serum albumin (HSA) depletion matrix. The stages of the research included the gradual cultivation of C. striata TBI, isolation of biosilica using biomass oxidation with nitric acid and calcination, physical and chemical characterization of C. striata TBI biosilica and study of HSA adsorption using batch and column methods. The results showed that C. striata TBI cells with an initial density of 500,000 cells L-1 increased to 3,000,000 cells L-1 on day 11 and produced biomass density 3.10 g L-1 or algal biomass productivity 220 mg L-1 day–1. The yield of biosilica extracted from C. striata TBI biomass was 60 mg L–1. The biosilica morphology of C. striata TBI looks like a tube (side view) and a circle (top view). The biosilica surface of C. striata TBI is filled with hundreds of nanometers pores which contain small pores about 3–5 nm (hierarchical pores). The results of the characterization using FTIR showed sharp peaks at wave numbers 802 cm-1 and 1082 cm-1 indicating the bending and stretching vibrations of Si-O-Si groups. The XRF spectrum shows that the biosilica obtained is 100% pure. The biosilica surface area of C. striata TBI was 130.64 m2/g and had a total pore volume of 2.89 x 10-1 cc/g and an average pore diameter of 4.43 nm. The adsorption kinetics model fitted to HSA adsorption was pseudo second order at both pH 3.5 and pH 7.5. The maximum adsorption capacity of biosilica was 8.66 mg g-1 following the Freundlich isotherm. The HSA adsorption efficiency obtained was around 52% at both pH 3.5 and 7.5 using the batch method and 60% at pH 7.5 using column (flow method). The best concentration for HSA adsorption is in the range 7.5–10 mg/mL with a contact time 5 minutes