Sensitive colorimetric detection of lysozyme in human serum using peptide-capped gold nanoparticles

This paper shows a simple, robust and sensitive colorimetric platform for lysozyme detection. This method is based on the fact that Cys-Ala-Leu-Asn-Asn (CALNN)-capped gold nanoparticles are linked by lysozyme specifically to form aggregates. The specific interaction between lysozyme and CALNN-capped gold nanoparticles is demonstrated by zeta potential determination, and comparison with some serum proteins, such as high-pI cytochrome c, low-pI HSA and insulin, as well as denatured lysozyme. Under the optimized conditions, a linear response range from 1 ng mL(-1) to 25 ng mL(-1) is obtained for lysozyme detection, and the limit of detection is 80 pg mL(-1). To the best of our knowledge, this is the most sensitive method without any amplification technology compared with the existing methods for lysozyme determination. Having sensitivity and selectivity, this method has capability to determine lysozyme in human serum. The serum lysozyme levels, obtained to be 7.5 mu g mL(-1) and 7.3 mu g mL(-1), are in good agreement with literature results.