July 2018
Volume 59, Issue 9
Open Access
ARVO Annual Meeting Abstract  |   July 2018
Cytotoxicity and ocular safety of silicic acid, the degradation product of porous silicon
Author Affiliations & Notes
  • Lingyun Cheng
    Jacobs Retina Center/Shiley Eye Institute, La Jolla, California, United States
  • William R Freeman
    Jacobs Retina Center/Shiley Eye Institute, La Jolla, California, United States
  • Kristyn Huffman
    Jacobs Retina Center/Shiley Eye Institute, La Jolla, California, United States
  • Yaoyao Sun
    Jacobs Retina Center/Shiley Eye Institute, La Jolla, California, United States
  • Footnotes
    Commercial Relationships   Lingyun Cheng, Spinnaker Bioscience (C); William Freeman, Spinnaker Bioscience (C); Kristyn Huffman, None; Yaoyao Sun, None
  • Footnotes
    Support  A) NIH EY020617. B) NIH P30EY022589. C) Research to prevent blindness.
Investigative Ophthalmology & Visual Science July 2018, Vol.59, 1192. doi:
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    • Get Citation

      Lingyun Cheng, William R Freeman, Kristyn Huffman, Yaoyao Sun; Cytotoxicity and ocular safety of silicic acid, the degradation product of porous silicon. Invest. Ophthalmol. Vis. Sci. 2018;59(9):1192.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose :
In recent years, porous silicon (pSi) has emerged as a novel drug carrier for controlled drug release. Compared with the traditional drug delivery vehicles such as liposomes or polymer particulates, pSi offers tunable nano-scaled pores for various sized payloads and adjustable drug release rates. The current study aims to characterize the ocular properties of sol-gel pSi particles and their degradation product, silicic acid (SiOH4).

Methods :
Two concentrations (low, 2.5µg/mL; high, 25µg/mL) of SiOH4 at two incubation durations (short, 5 days; long, 5 weeks) were designed to assess the safety concentration and the safety of exposure time. EA.hy926 cells were exposed to SiOH4 and cytotoxicity was determined by WST-1 assay. In addition, various particle and pore sizes of sol-gel pSiO2 particles were monitored in a daily static release to discover the SiOH4 dissolution kinetics before 8mg of intravitreal injection in 4 rabbit eyes.

Results : WST-1 cytotoxicity data demonstrated that SiOH4 at 2.5µg/mL was not cytotoxic but 25µg/mL was when compared to the control (p<0.0001). The cells with five-week exposure to SiOH4 showed cytotoxicity when compared with 5-day exposure (p<0.0001) (Figure 1). SiOH4 release profiles from the three formulations of pSiO2 particles is shown in figure 2. SiOH4 dissolution rates from the sol-gel pSiO2 particles were pore-size dependent (p<0.0001). Four rabbit eyes with 8mg intravitreal dose did not show any toxicity in clinical and ERG exams.

Conclusions :
The in vitro study suggested SiOH4 cytotoxicity at high concentration or long-term exposure; however, in vivo study revealed minimal toxicity. SiOH4 dissolution rate from the pSiO2 particles is pore-size dependent both in vitro and in vivo.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.

 


The box-plots of the cytotoxicity OD values stratified by source of silicic acid, concentration of silicic acid, and exposure time of silicic acid to the cultured EA.hy926 cells.


The box-plots of the cytotoxicity OD values stratified by source of silicic acid, concentration of silicic acid, and exposure time of silicic acid to the cultured EA.hy926 cells.

 

In vitro silicic acid dissolution kinetics from the sol-gel pSiO2 particles.

In vitro silicic acid dissolution kinetics from the sol-gel pSiO2 particles.

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