Quaternized magnetic nanoparticles–fluorescent polymer system for detection and identification of bacteria

• ‘Chemical nose’ based on q-MNP–fluorescent polymer systems has been designed.
• Based on the response matrix from LDA, the method has been used to measure bacteria.
• The method is used to identify pathogens with an accuracy of 96.8%.

Nanomaterial-based ‘chemical nose’ sensor with sufficient sensing specificity is a useful analytical tool for the detection of toxicologically important substances in complicated biological systems. A sensor array containing three quaternized magnetic nanoparticles (q-MNPs)–fluorescent polymer systems has been designed to identify and quantify bacteria. The bacterial cell membranes disrupt the q-MNP–fluorescent polymer, generating unique fluorescence response array. The response intensity of the array is dependent on the level of displacement determined by the relative q-MNP–fluorescent polymer binding strength and bacteria cells–MNP interaction. These characteristic responses show a highly repeatable bacteria cells and can be differentiated by linear discriminant analysis (LDA). Based on the array response matrix from LDA, our approach has been used to measure bacteria with an accuracy of 87.5% for 107 cfu mL−1 within 20 min. Combined with UV–vis measurement, the method can be successfully performed to identify and detect eight different pathogen samples with an accuracy of 96.8%. The measurement system has a potential for further applications and provides a facile and simple method for the rapid analysis of protein, DNA, and pathogens.