Hydrophobic quercetin encapsulated hemoglobin nanoparticles: formulation and spectroscopic characterization

Abstract

Various natural proteins are finding application in drug delivery for their high biodegradability and biocompatibility. Albumins are well explored and now focus is shifting to other proteins like hemoglobin (Hb) with unique structural properties. In the present study Hb is allowed to denature at pH 5.0 and model hydrophobic drug quercetin (Q) is encapsulated via self-assembly and hydrophobic interactions. Fluorimetric titrations record highest binding between Hb and Q at pH 5.0, rendering significant structural changes in Hb as captured in CD spectra. A decrease in fluorescence life time of tryptophan residues from 3.31 ns in Hb to 2.89 ns in presence of Q at pH 5.0; surmises efficient binding of Q at the hydrophobic core housing tryptophan. Peak shifts in Fourier transform infrared spectroscopy spectra of Hb-Q compared to Hb evidence significant interactions between them at pH 5.0. Significant spectral changes in soret band region of Hb on addition of Q at pH 5.0 envisages unfolding of porphyrin ring and binding influence of Q. Efficient formation of Hb-Q nanoparticles (NPs) at pH 5.0 is established by DLS, SEM and TEM.

Communicated by Ramaswamy H. Sarma

Keywords:

• Hemoglobin
• quercetin
• self-assembly
• encapsulation
• nanoparticles
• spectroscopy

Acknowledgements

The authors are thankful to UGC-DAE Consortium for Scientific Research, Kolkata for the financial research grant and for providing us instrumental facilities like DLS, Zeta potential, ITC, Fluorimeter and UV- Vis Spectrophotometer. Thanks are also extended to Centre for Research in Nano Science and Nano Technology, Kolkata for providing us with SEM and TEM facility and Bose Institute for CD facility. The Vice-Chancellor of MAKAUT, Prof. Saikat Maitra is acknowledged for his constant support and encouragement.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The authors are thankful to UGC-DAE Consortium for Scientific Research, Kolkata for the financial research grant and for providing us instrumental facilities like DLS, Zeta potential, ITC, Fluorimeter and UV- Vis Spectrophotometer.