Functional Porous Silicon Nanocomposites For Cancer Therapy

Porous silicon nanoparticles(PSi NPs)have unique fluorescent properties,tailored surface functionalization and exc ellent biodegradability,etc.,resulting in widely applicaitons on the biomedical imaging,drug delivery and cancer therapy.In our thesis,after different biofunctionalizations,PSi NPs-based nanocomposites were systematically studied in fluorescent imaging,drug delivery,and combination therapy.The main contents of this thesis were showed as followed:First,PSi NPs were fabricated by electrochemical etching and ultra-sonication.Then divinylbenzene molecules was grafted onto hydrogen-terminated PSi NPs via microwave-induced hydrosilylation to prepare s tyrene-terminated PSi NPs(SPSi NPs),with their fluorescence emission wavelength shifting from ~ 600 nm to ~700 nm.After bovine serum albumin(BSA)encapsulation via hydrophobic interactions,hydrophobic S-PSi NPs were changed to hydrophilic BSA/S-PSi NPs nanocomposites with high water-dispersibility.Notably,these BSA/S-PSi NPs nanocomposites had stable near-infrared(NIR)fluorescence under physiological conditions.Finally,as-prepared BSA/S-PSi NPs nanocomposites with excellent biocompatibility exhibited good potential on fluorescence imaging in vivo.We present a novel strategy of incorporating doxorubicin(DOX)into styrene-terminated PSi NPs(S-PSi NPs)via π-π stacking to form DOX@S-PSi NPs nanocomposites,which had a high-loading amount of DOX molecules.In addition,p H-controlled release of DOX molecules from the DOX@S-PSi NPs nanocomposites was also observed.After cellular internalization of DOX@S-PSi NPs,the DOX molecules could be also sustainedly released in the cancer cells,which prolonged their anticancer performance in vitro.After the modification with the silane coupling agent(APTES),NH2-PSi NPs with positive charge were loaded with DOX and IR820 molecules via electrostatic interactions to prepare DOX/IR820/NH2-PSi NPs nanocomposites.DOX/IR820/NH 2-PSi NPs nanocomposites had a good biodegradability,NIR light-controlled release of DOX,and significant combination therapy effect in vitro.In particular,with twophoton laser confocal microscopy,we used FRAP technology to realize in situ observation of DOX intracellular release from DOX/IR820/NH2-PSi NPs nanocomposites under NIR laser stimulation.Polyaniline/porous silicon hybrid nanocomposites(PANi-PSi NPs)had been successfully fabricated via surface-initiated polymerization of aniline onto PSi NPs.These resultant PANi-PSi NPs showed a robust and stable photothermal effect.Compared with bare PSi NPs,the degradation rate of PANi-PSi NPs decreased,however,they still retained a significant degradation in vitro.Toxicological studies of PANi-PSi NPs in vivo were further carried out,which showed that they could be effectively degraded in body and had good biocompatibility.On this basis,PANi-PSi NPs as a carrier to load DOX,exhibited a good anticancer performance of combination treatments including chemotherapy and photothermal therapy.