| Gold nanoparticles fascinate tremendous interests due to its unique photophysicalproperties and good biocompatibility for various biomedical applications. Amongdifferent shapes of gold nanoparticles, gold nanoshells can tune their surface Plasmonresonance (SPR) in a wider range by changing the core-to-shell relative dimension.Also, its larger specific surface area, robust structure, better stability and potentialityfor inner-containing carrier render gold nanoshells a promising candidate inbiomedicine and cancer therapy.In our investigation, there are still some problems of synthesis of gold nanoshells.Typical method to synthesize gold nanoshells involved the fabrication and modificationof templates, synthesis and attachment of gold cluster, further growth of gold shell. Toobtain final product, additional centrifugation and re-dispersion was inevitable andalways introduced low yield and a significant aggregation. To realize the regulation ofSPR, either synthesizing gold nanoshells with different thickness on a constant core orsynthesizing different sized core with a constant-thickness gold shell was applied.However, the regulation of SPR was barely satisfactory. Secondly, to realize biomedicalapplication, stability and photothermal conversion properties of gold nanoshells withdifferent sizes deserved further investigation. Based on the investigation and analysismentioned above, the article could be divided in two parts:Firstly, a one-pot synthetic strategy for fabricating hollow gold nanoshells using3- aminopropyltriethoxysilane-in-water suspension template has been described, theeffect of several experimental conditions were studied. All experiments were conductedin ambient atmosphere and the process could accomplish within1minute. UV-Vis，TEM，SEM，HRTEM，EDX mapping measurements were carried out to confirm thehollow structure of gold nanoshells. We found out that the size of APTES could besignificantly affected by the concentration of HAuCl4and increased as theconcentration of HAuCl4increased. When the HAuCl4to APTES ratio increased from0.06:1to0.12:1,0.18:1,0.24:1and0.30:1, the APTES droplet increase from117to138,155,167and180nm, the outer diameter of the as-synthesized gold nanoshells increasedfrom37nm to42,61,83and96nm, the relative SPR shifted from657nm to720,755,832and957nm. There was no change in shell thickness. The ethanol to water ratio alsohad impact in size of APTES thus gold nanoshells. When fixing the concentration ofAPTES and HAuCl4, the outer diameter of gold nanoshells changed from83to60and43nm with a constant shell thickness of about10nm when the ethanol to water ratioincreased from0:10to1:9and2:8, and the corresponding SPR shifted from832nm to762and692nm. However, when the ethanol to water ratio was higher than7:3, therewould not be gold nanoshells but aggregation of small gold nanoparticles.Secondly, the successful synthesis of gold nanoshells with different diametersfacilitated us to explore the stability and photothermal properties of gold nanoshells.Gold nanoshells stabilized by Sodium Citrate (1mM) aggregated within30min afterformation, while gold nanoshells stabilized by BSA (0.01mM) had good stability even3days after formation. In photothermal conversion experiments, temperature changecurves of gold nanoshells (A808nm=0.8) with average sizes of37,42,61,83and96nmwere recordedand their photothermal conversionefficiencywere calculated byRoper’sequation, photothermal conversion efficiency of gold nanoshells with an outer diameterof37,42,61,83and96nm was45%，41.1%，40.0%，36.6%. Stability of the hollowgold nanoshells was further investigated by6turn on/off cycles. The repeatabletemperature change trend together with the overlap UV-Vis spectral results before andafter cycle tests indicated the excellent photothermal stability of the as-prepared hollowgold nanoshells. These evidences showed that the as-synthesized gold nanoshells had great potential in biomedicine and cancer therapy. |
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