Study on the biostability of chlorophyll a entrapped in silica gel nanomatrix

Chlorophyll a has been extracted mainly from fresh leaves and subsequently entrapped in nano porous silica gel matrix through the sol gel route under varying pH conditions. UV-VIS spectroscopy fluorescence and FTIR spectroscopy have been carried out to study the structure and stability of entrapped chlorophyll as a function of sol pH and time after entrapment. It is observed that chlorophyll molecules remain structurally unaltered on entrapment of sol pH of 6.8. Increasing acidic condition indicates gradual changes of chlorophyll extracts e.g., removal of Mg. However once entrapped chlorophyll molecules remain stable irrespective of the sol pH condition. Chlorophyll molecules entrapped in silica gel matrix also appear resistant to degradation by water. It has been proposed that pyroll type ring of the porphyrene moiety forms a weak bond with the unfilled d orbital of the matrix silicon. This imparts stabilization of chlorophyll within silica gel matrix, without any external stabilization agent.