Evaluation of Gallium as a Tracer of Exogenous Hemoglobin-Haptoglobin Complexes for Targeted Drug Delivery Applications.
Haptoglobin (Hp) is a plasma glycoprotein that generates significant interest in the drug delivery community because of its potential for delivery of antiretroviral medicines with high selectivity to macrophages and monocytes, the latent reservoirs of human immunodeficiency virus. As is the case with other therapies that exploit transport networks for targeted drug delivery, the success of the design and optimization of Hp-based therapies will critically depend on the ability to accurately localize and quantitate Hp-drug conjugates on the varying and unpredictable background of endogenous proteins having identical structure. In this work, we introduce a new strategy for detecting and quantitating exogenous Hp and Hp-based drugs with high sensitivity in complex biological samples using gallium as a tracer of this protein and inductively coupled plasma mass spectrometry (ICP MS) as a method of detection. Metal label is introduced by reconstituting hemoglobin (Hb) with gallium(III)-protoporphyrin IX followed by its complexation with Hp. Formation of the Hp/Hb assembly and its stability are evaluated with native electrospray ionization mass spectrometry. Both stable isotopes of Ga give rise to an abundant signal in ICP MS of a human plasma sample spiked with the metal-labeled Hp/Hb complex. The metal label signal exceeds the spectral interferences' contributions by more than an order of magnitude even with the concentration of the exogenous protein below 10 nM, the level that is more than adequate for the planned pharmacokinetic studies of Hp-based therapeutics. Graphical Abstract ᅟ.
Department of Chemistry, University of Massachusetts, Amherst, MA, 01003, USA.
Shengsheng
S
Xu
Department of Chemistry, University of Massachusetts, Amherst, MA, 01003, USA. kaltashov@chem.umass.edu.
Igor A
0000-0002-4355-6039
IA
Kaltashov
D016503:Drug Delivery Systems; D005708:Gallium / Q000032:analysis*; D006242:Haptoglobins / Q000032:analysis*; D006454:Hemoglobins / Q000032:analysis*; D006801:Humans; D007202:Indicators and Reagents; D021241:Spectrometry, Mass, Electrospray Ionization
D006242:Haptoglobins; D006454:Hemoglobins; D007202:Indicators and Reagents; D005708:Gallium
Human immunodeficiency virus; Metal tags; Native electrospray ionization mass spectrometry; Noncovalent complexes; Protein labeling; Protein therapeutics; Targeted drug delivery