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. Author manuscript; available in PMC: 2021 Apr 10.

Published in final edited form as: Small. 2021 Mar 7;17(14):e2005993. doi: 10.1002/smll.202005993

Fig. 2. — Design, synthesis and characterization of silicasomes, that contain the activated Pt drug. (A) The top panel provides a schematic that outlines the synthesis steps for tailored construction of silicasomes, incorporating the active Pt drug. The key parameters that govern successful drug loading are outlined in the table (lower panel). (B) pH adjustment to attain weak-basic conditions, favorable for drug loading. At basic pH, silanol groups can be ionized, i.e. ≡Si–OH ⇔ ≡Si–O⁻ (B1), leading to a surface that allows efficient drug attachment via coordination chemistry and electrostatic binding (B2). (C) Zeta potential value of bare MSNP is pH-dependent. The development of a negative surface charge at pH 8.5 leads to the highest level of Pt drug binding, as exemplified by DACHPt. Other loading parameters, such the sonication condition, feed ratio, incubation time, etc., were systemically optimized, as illustrated online (Fig. S2). (D) After experimenting with multiple reaction conditions, it was possible to accomplish a ~5x increase in terms of EE% and LC%, as determined by ICP-MS analysis of Pt. The same binding level could not be achieved by a passive loading strategy. (E) Ultrastructural in situ STEM-EDS imaging confirmed the improved drug loading by coordination chemistry and electrostatic binding. The Pt/Si ratio (w/w) was determined to be 19.4% for the DACHPt silicasome, which is ~6x higher than a silicasome passively entrapping oxaliplatin. (F) And approximate 5–9x fold improvement in drug loading was also achieved for DAPt and EDAPt, according to ICP-MS analysis; this was also confirmed by STEM-EDS visualization. The hydrodynamic sizes of DAPt silicasome and EDAPt silicasome were 138.1 ± 1.5 nm (PDI: 0.113) and 137.8 ± 0.2 nm (PDI: 0.146).

Fig. 2. — Design, synthesis and characterization of silicasomes, that contain the activated Pt drug. (A) The top panel provides a schematic that outlines the synthesis steps for tailored construction of silicasomes, incorporating the active Pt drug. The key parameters that govern successful drug loading are outlined in the table (lower panel). (B) pH adjustment to attain weak-basic conditions, favorable for drug loading. At basic pH, silanol groups can be ionized, i.e. ≡Si–OH ⇔ ≡Si–O⁻ (B1), leading to a surface that allows efficient drug attachment via coordination chemistry and electrostatic binding (B2). (C) Zeta potential value of bare MSNP is pH-dependent. The development of a negative surface charge at pH 8.5 leads to the highest level of Pt drug binding, as exemplified by DACHPt. Other loading parameters, such the sonication condition, feed ratio, incubation time, etc., were systemically optimized, as illustrated online (Fig. S2). (D) After experimenting with multiple reaction conditions, it was possible to accomplish a ~5x increase in terms of EE% and LC%, as determined by ICP-MS analysis of Pt. The same binding level could not be achieved by a passive loading strategy. (E) Ultrastructural in situ STEM-EDS imaging confirmed the improved drug loading by coordination chemistry and electrostatic binding. The Pt/Si ratio (w/w) was determined to be 19.4% for the DACHPt silicasome, which is ~6x higher than a silicasome passively entrapping oxaliplatin. (F) And approximate 5–9x fold improvement in drug loading was also achieved for DAPt and EDAPt, according to ICP-MS analysis; this was also confirmed by STEM-EDS visualization. The hydrodynamic sizes of DAPt silicasome and EDAPt silicasome were 138.1 ± 1.5 nm (PDI: 0.113) and 137.8 ± 0.2 nm (PDI: 0.146).