Evaluation of silver nanoparticle encapsulation in DPPC-based liposome by different methods for enhanced cytotoxicity

Abstract

Here we carried out a comparative study on two cost and time effective methods of encapsulating silver nanoparticles (AgNP) in dipalmitoyl-phosphatidyl choline (DPPC)/cholesterol-based liposome to enhance its cytotoxicity and reduce cytotoxic concentrations and evaluated the effect of this on a blood cell line (THP1 monocytes) often involved in uptake of nanoparticles during human exposure. DLS and Zeta potential analyses over a 6-months period showed the extruded Lipo-AgNP (ExLipo-AgNP) exhibited more stable characteristics when compared with the probe-sonicated Lipo-AgNP (PB-Lipo-AgNP). SEM microscopy indicated agglomeration of the PB-Lipo-AgNP which was not observed in Ex-Lipo-AgNP. Ex-Lipo-AgNP also exhibited higher temperaturedependent stability with 35.3% reduction in size from 20 C to 37 C while PB-Lipo-AgNP was less stable exhibiting 55% size reduction over same temperature range. Load release study over 24 h showed a controlled load release from Ex-Lipo-AgNP while the PB-Lipo-AgNP exhibited burst release at pH 4 and 6.5. Interestingly, it was found that Ex-Lipo-AgNP induced significantly higher toxicity on THP1 cell line after 24 h exposure compared with control unexposed cells; uncoated AgNP and PB-Lipo-AgNP exposed cells at the same concentration. Thus, for the first time, we report that liposomal encapsulation of AgNP by extrusion produces a stable nanocapsule with enhanced cytotoxicity, thus preventing overreliance on high AgNP concentration to achieve desired toxicity.

Build-Up of a 3D Organogel Network within the Bilayer Shell of Nanoliposomes. A Novel Delivery System for Vitamin D3: Preparation, Characterization, and Physicochemical Stability

“…These results are similar to those previously reported by Kakami et al . and Yusuf and Casey, who reported 128 and 140 nm for nanoliposomes obtained by the extrusion process, respectively.…”

“…These small values of PDI (<0.3) indicate a very narrow size population of nanoliposomes 48 in both fresh samples. These results are similar to those previously reported by Kakami et al 49 and Yusuf and Casey, 50 who reported 128 and 140 nm for nanoliposomes obtained by the extrusion process, respectively.…”

Surface modification of silver nanoparticle (AgNP) by liposomal encapsulation mitigates AgNP-induced inflammation

“…As such, AgNP stimulation of IL-8 release may facilitate IL-8 chemokine activity in the same manner. This may also explain the hormetic effect of AgNP in stimulating THP1 cell proliferation (Yusuf and Casey, 2019)and in HepG2 and A549 cancer cells (Jiao et al, 2014;Sthijns et al, 2017). Interestingly, HepG2 cell proliferation have been shown in another study to be inhibited by gallic acid through inhibition of IL-8 secretion (Lima et al, 2016), highlighting the possible contribution of AgNP-induced IL=8 secretion to cancer cell proliferation.…”

“…Detail of the nanoparticle characterisation and toxicity profile for AgNP and Lipo-AgNP as well as the drug release profile of Lipo-AgNP in aqueous environment at physiological pH of 7 and acidic pH of 6.5 is present in our recent publication (Yusuf and Casey, 2019). In summary, the DLS analysis of the nanoparticles used in this study are depicted in Table 1 below.…”

Synthesis and characterization of liposomes encapsulating silver nanoprisms obtained by millifluidic-based production for drug delivery

“…The encapsulation of AgNPs within a carrier system may provide an efficient route to potentially reduce their systemic toxicity. In efforts to achieve localized delivery of AgNPs while minimizing toxic side-effects, previous in vitro studies have demonstrated that delivery of AgNPs within liposomes was associated with greater therapeutically favourable effects at lower concentrations, when compared to the delivery of unencapsulated AgNPs alone [25,26]. These earlier findings thus suggest that encapsulation of SNPs in liposomes offers a promising route for reducing off-target systemic effects, as well as providing a potential platform for co-delivery of AgNPs together with active pharmaceutical ingredients to achieve controlled and localized drug delivery.…”