Fluorescence imaging of human erythrocytes by carbon nanoparticles isolated from food stuff and their fluorescence enhancement by blood plasma

We have isolated carbon nanoparticles (CNPs) from bread. A simple oxidative treatment make them water soluble and fluorescent. CNPs exhibit fluorescence over a broad range of excitation wavelengths. These fluorescent CNPs have been susscessfully used for fluorescence imaging of human erythrocytes under 488 and 561 nm bandpass filters. Upon direct interaction with human erythrocytes, these CNPs show ∼6% haemolysis in 5 h. In the presence of blood plasma, the quantum yield of these water soluble carbon nanoparticles enhances from 2 to 4.5% leading to rise a new phenomenon of auto passivation of CNPs by bio-fluids. Therefore, these fluorescent CNPs can be used as a unique and new type of biomaterial for bioimaging and other biomedical applications.