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Synthesis, characterization, and mechanistic studies of a gold nanoparticle–amphotericin B covalent conjugate with enhanced antileishmanial efficacy and reduced cytotoxicity

Authors Kumar P, Shivam P, Mandal S, Prasanna P, Kumar S, Prasad SR, Kumar A, Das P, Ali V, Singh SK, Mandal D

Received 11 December 2018

Accepted for publication 10 May 2019

Published 20 August 2019 Volume 2019:14 Pages 6073—6101


Checked for plagiarism Yes

Review by Single anonymous peer review

Peer reviewer comments 3

Editor who approved publication: Prof. Dr. Thomas J. Webster

Prakash Kumar,1 Pushkar Shivam,*,2 Saptarshi Mandal,*,3 Pragya Prasanna,1 Saurabh Kumar,1 Surendra Rajit Prasad,1 Ashish Kumar,4 Prolay Das,3 Vahab Ali,5 Shubhankar Kumar Singh,2 Debabrata Mandal1

1Department of Biotechnology, National Institute of Pharmaceutical Education and Research (NIPER) – Hajipur, Vaishali, India; 2Department of Microbiology, Rajendra Memorial Research Institute of Medical Sciences, Patna, India; 3Department of Chemistry, Indian Institute of Technology Patna, Patna, India; 4Department of Molecular Biology, Rajendra Memorial Research Institute of Medical Sciences, Patna, India; 5Department of Biochemistry, Rajendra Memorial Research Institute of Medical Sciences, Patna, India

*These authors contributed equally to this work

Background: Amphotericin B (AmB) as a liposomal formulation of AmBisome is the first line of treatment for the disease, visceral leishmaniasis, caused by the parasite Leishmania donovani. However, nephrotoxicity is very common due to poor water solubility and aggregation of AmB. This study aimed to develop a water-soluble covalent conjugate of gold nanoparticle (GNP) with AmB for improved antileishmanial efficacy and reduced cytotoxicity.
Methods: Citrate-reduced GNPs (∼39 nm) were functionalized with lipoic acid (LA), and the product GNP-LA (GL ∼46 nm) was covalently conjugated with AmB using carboxyl-to-amine coupling chemistry to produce GNP-LA-AmB (GL-AmB ∼48 nm). The nanoparticles were characterized by dynamic light scattering, transmission electron microscopy (TEM), and spectroscopic (ultraviolet–visible and infrared) methods. Experiments on AmB uptake of macrophages, ergosterol depletion of drug-treated parasites, cytokine ELISA, fluorescence anisotropy, flow cytometry, and gene expression studies established efficacy of GL-AmB over standard AmB.
Results: Infrared spectroscopy confirmed the presence of a covalent amide bond in the conjugate. TEM images showed uniform size with smooth surfaces of GL-AmB nanoparticles. Efficiency of AmB conjugation was ∼78%. Incubation in serum for 72 h showed <7% AmB release, indicating high stability of conjugate GL-AmB. GL-AmB with AmB equivalents showed ∼5-fold enhanced antileishmanial activity compared with AmB against parasite-infected macrophages ex vivo. Macrophages treated with GL-AmB showed increased immunostimulatory Th1 (IL-12 and interferon-γ) response compared with standard AmB. In parallel, AmB uptake was ∼5.5 and ∼3.7-fold higher for GL-AmB-treated (P<0.001) macrophages within 1 and 2 h of treatment, respectively. The ergosterol content in GL-AmB-treated parasites was ∼2-fold reduced compared with AmB-treated parasites. Moreover, GL-AmB was significantly less cytotoxic and hemolytic than AmB (P<0.01).
Conclusion: GNP-based delivery of AmB can be a better, cheaper, and safer alternative than available AmB formulations.

Keywords: gold nanoparticle, amphotericin B, antileishmanial, macrophage uptake, ergosterol, immunostimulator

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