Systematic Evaluation of Transferrin-Modified Porous Silicon Nanoparticles for Targeted Delivery of Doxorubicin to Glioblastoma

Abstract

There is a dire need to develop more effective therapeutics to combat brain cancer such as glioblastoma multiforme (GBM). An ideal treatment is expected to target deliver chemotherapeutics to glioma cells across the blood–brain barrier (BBB). The overexpression of transferrin (Tf) receptor (TfR) on the BBB and the GBM cell surfaces but not on the surrounding cells renders TfR a promising target. While porous silicon nanoparticles (pSiNPs) have been intensely studied as a delivery vehicle due to their high biocompatibility, degradability, and drug-loading capacity, the potential to target deliver drugs with transferrin (Tf)-functionalized pSiNPs remains unaddressed. Here, we developed and systematically evaluated Tf-functionalized pSiNPs (Tf@pSiNPs) as a glioma-targeted drug delivery system. These nanoparticles showed excellent colloidal stability and had a low toxicity profile. As compared with nontargeted pSiNPs, Tf@pSiNPs were selective to BBB-forming cells and GBM cells and were efficiently internalized through clathrin receptor-mediated endocytosis. The anticancer drug doxorubicin (Dox) was effectively loaded (8.8 wt %) and released from Tf@pSiNPs in a pH-responsive manner over 24 h. Furthermore, the results demonstrate that Dox delivered by Tf@pSiNPs induced significantly enhanced cytotoxicity to GBM cells across an in vitro BBB monolayer compared with free Dox. Overall, Tf@pSiNPs offer a potential toolbox for enabling targeted therapy to treat GBM.

Transferrin-targeted porous silicon nanoparticles reduce glioblastoma cell migration across tight extracellular space

“…Unlike Tf, BSA is an inert protein abundantly present in serum and it is reported that BSA modification did not enhance NP uptake via clathrin-mediated receptor-mediated endocytosis 34 . This explains that the uptake was apparently slower as detailed in our previous work 35 . Additionally, the internalisation of Tf@pSiNP in U87 cells was confirmed by means of cryo-TEM imaging ( Fig.…”

“…As predicted, Tf@pSiNP were non-toxic and did not reduce ATP amount in GBM cells, in agreement to other pSiNP studies in vitro and in vivo 23,51 . In a separate study, we also showed that Tf@pSiNP is also highly tolerable in human cerebral microvascular cells, and non-CNS keratinocytes over a wide range of concentration 35 , highlighting the biocompatibility of those nanoparticles. Since the cells exposed to Tf alone were also highly viable, the amount of Fe 2+ released from Tf did not cause detrimental effects such as ferroptosis 52 .…”

“…Cryo-TEM imaging of nanoparticles. The Cryo-TEM was conducted following our previously described protocol 35 . Briefly, a 3 µL sample of NP in PBS was dispensed onto a glow discharged copper grid (300 mesh) with lacey carbon film coating (ProSciTech, QLD, Australia).…”

“…After 24 h, the cells were washed to remove the non-internalised nanoparticles. The preparation of TEM samples was conducted according to the protocol described by Luo et al 35 . Briefly, the cells were first harvested by trypsinisation, and pelleted at 200 rcf.…”

“…This primary cell was also tested negative for mycoplasma contamination.Porous silicon nanoparticle (pSiNP) preparation. pSiNP was fabricated according to a previously reported procedure 23,35 . p+ type (0.01-0.02 Ω cm) silicon wafers (Siegert Consulting Co., Aachen, Germany) etched periodically at 50 (2.2 s period) and 200 (0.35 s period) mA/cm 2 in a solution of 1:1 HF (38%):ethanol (EtOH) for 20 min.…”