Abstract
Mesoporous silica nanoparticles (MSN) covered by polymer coatings, cross-linked by weak coordination bonds were expected to present a reversible responsiveness under on-off ultrasound stimuli. Herein, we prepared a sodium alginate (SA) modified MSN with carboxyl-calcium (COO−-Ca2+) coordination bonds in the modified layer, which could block the mesopores of MSN and effectively prevent the cargo from pre-releasing before stimulation. The coordination bonds would be destroyed under the stimulation of low intensity ultrasound (20 kHz) or high intensity focused ultrasound (HIFU, 1.1 MHz), leading to a rapid and significant cargo release, and then they could be reformed when ultrasound was turned off, resulting in an instant cargo release stopping. The reversible cleavage and reformation of this coordination bonds under on-off ultrasound stimulus were confirmed by the gel-sol transition behaviors of the SA-CaCl2 gels. An excellent real-time control of rhodamine B (RhB) release performance was obtained under the ultrasound stimuli. Obviously, the cargo release ratio could reach to nearly 40% when HIFU (80 W) was turned on for 5 min, and remained basically constant when ultrasound was turned off, which would finally reach to nearly 100% within 30 min under this on-off pulsatile status. These hybrid MSN based nanoparticles with excellent reversible ultrasound on-off responsiveness were of great interest in on-demand drug delivery applications in the future.
Highlights
During recent decades, with the development of nanotechnology, nanoparticles have been widely applied and well-developed in the field of biomedicine for drug delivery
Among various nanomaterials employed for drug delivery applications, the fast-growing attention to mesoporous silica nanoparticles (MSN) has been vastly highlighted due to their outstanding properties, such as large specific surface areas, uniform pores with adjustable structures, excellent biocompatibility, and thermal stability, as well as a facile modification on surface (Trewyn et al, 2007; Chang et al, 2013; Argyo et al, 2014; Paris et al, 2015)
Sodium alginate (SA) polymers were grafted onto the amino modified MSN (MSN-NH2), which was cross-linked by CaCl2 solution to form the COO−-Ca2+ coordination bonds
Summary
With the development of nanotechnology, nanoparticles have been widely applied and well-developed in the field of biomedicine for drug delivery. In order to verify our hypothesis and obtain a novel kind of reversible ultrasound responsive drug carrier, we prepared a novel kind of hybrid MSN by grafting sodium alginate (SA) polymer onto the MSN surface, which was further cross-linked by CaCl2 solution after cargo loading.
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