Application of silica extracted from rice husk ash for the encapsulation of AFB₁ antibody as a matrix in immunoaffinity columns

Abstract

  The extraction of silica from rice husk ash (RHA) for the encapsulation of aflatoxin B₁ antibody (Ab-AFB₁) and its application as a matrix in immunoaffinity columns (IACs) were achieved. The RHA extraction was performed using 4 M NaOH, which yielded sodium silicate (Na₂SiO₃) for the synthesis of silica gel. The obtained silica was used for encapsulating Ab-AFB₁ using the sol-gel technique. One milliliter of 1 M Na₂SiO₃:H₂O:H₃PO₄ (0.43:0.11:0.46) could generate silica gel that was suitable for encapsulating 1.36 mg of Ab-AFB₁ at pH 7. After 48 hours of aging, the silica gel modified with Ab-AFB₁ (SG-Ab-AFB₁) was ground, and packed as the matrix in the IAC for aflatoxins purification. The modified silica gel was characterized using FTIR and SEM. The properties of IAC with SG-Ab-AFB₁ were investigated by evaluating AF recovery, binding capacity, and reusability. The recovery of AFB₁ was 94.11 ± 4.62%. In addition to AFB₁ recovery, the column also retained AFB₂, AFG₁, and AFG₂ with recovery values of 98.22 ± 3.74%, 92.22 ± 7.62%, and 83.00 ± 6.31%, respectively. This column, which contained 0.5 g of SG-Ab-AFB₁ had a binding capacity of approximately 50 ng of AFs per column, and could be reused at least 5 times with a recovery of more than 80%.