Smart Nanoparticles as Near-Infrared Fluorescent Biomarkers
Vishal Saxena, Drug Delivery & Biotechnology Laboratory, College of Pharmacy and Health Sciences
Mostafa Sadoqi, Department of Physics, St. John’s College of Liberal Arts and Sciences
Jun Shao, Department of Pharmacy and Administrative Sciences, College of Pharmacy and Health Sciences
The objective of this study is to develop a stable, biodegradable, biocompatible, nontoxic and targetable near-infrared nanobiomarker. Poly(dl-lactic-co-glycolic acid) (PLGA) nanoparticles were engineered by entrapping near-infrared fluorescent dye Indocyanine green (ICG) and the overall stability provided to ICG by the nanoparticle delivery system in aqueous media was established.
PLGA nanoparticles entrapping ICG were prepared by a modified spontaneous emulsification solvent diffusion method. The ICG entrapment in nanoparticles was determined and physicochemical characterization of nanoparticles was performed. The degradation kinetics of ICG was investigated in aqueous solution and aqueous nanoparticles suspension by steady-state fluorescence technique and order of degradation was determined. The influence of ICG entrapment in nanoparticles on fluorescence spectra of ICG and on degradation of ICG in aqueous media, photodegradation and thermal degradation were studied. PEG coating of the nanoparticles was performed to prolong in-vivo circulation time thus providing passive tumor targeting.
PLGA nanoparticles with mean diameter of 357 ~ 21 nm and ICG entrapment of about 74% were obtained. The degradation of ICG in aqueous solution and in aqueous nanoparticles suspension follows first order kinetics for the time period studied. The entrapment of ICG in nanoparticles causes a shift in its wavelength of peak fluorescence and decrease in its peak fluorescence intensity. The entrapment in nanoparticles provides high stability to ICG degradation in aqueous medium along with efficient photostability and thermal stability to ICG. An efficient PEG coating of the nanoparticle surface was obtained.
This investigation shows that the degradation of ICG in aqueous media follows first order kinetics. The nanoparticles formulation provides overall stability to degradation of ICG in aqueous media and thus emerges as an efficient near-infrared fluorescent nanobiomarker system having a tumor targeting ability.