Abstract
Au nanorods (AuNRs) have attracted a great interest as a platform for constructing various composite core/shell nanoparticles for theranostics applications. However, the development of robust methods for coating AuNRs with a biocompatible shell of high loading capacity and with functional groups still remains challenging. Here, we coated AuNRs with a polydopamine (PDA) shell and functionalized AuNR-PDA particles with folic acid and rhodamine 123 (R123) to fabricate AuNR-PDA-R123-folate nanocomposites. To the best of our knowledge, such AuNR-PDA-based composites combining fluorescent imaging and plasmonic phothothermal abilities have not been reported previously. The multifunctional nanoparticles were stable in cell buffer, nontoxic and suitable for targeted fluorescent imaging and photothermal therapy of cancer cells. We demonstrate the enhanced accumulation of folate-functionalized nanoparticles in folate-positive HeLa cells in contrast to the folate-negative HEK 293 cells using fluorescent microscopy. The replacement of folic acid with polyethylene glycol (PEG) leads to a decrease in nanoparticle uptake by both folate-positive and folate-negative cells. We performed NIR light-mediated targeted phototherapy using AuNR-PDA-R123-folate and obtained a remarkable cancer cell killing efficiency in vitro in comparison with only weak-efficient nontargeted PEGylated nanoparticles. Our work illustrates that AuNR-PDA could be a promising nanoplatform for multifunctional tumor theranostics in the future.
Highlights
Multifunctional imaging and combined multimodal therapy strategies are very promising in cancer theranostics [1,2]
We present PDA-coated NIR-absorbing Au nanorods (AuNRs) and used the potential of the PDA layer for folate surface functionalization and rhodamine 123 (R123) loading, resulting in the formation of AuNR-PDA-R123-folate nanocomposites (Scheme 1). This platform demonstrates three distinct features: (1) targeting of nanocomposites with folic acid leads to enhanced cellular uptake by folate-positive cancer cells compared with PEGcoated nanorods; (2) the high loading with rhodamine 123 makes the nanoparticles suitable for cell imaging with a simple fluorescent microscope; (3) through using NIR-mediated photothermal therapy the cancer cells can be killed with a high efficiency
According to statistical data derived from Transmission electron microscopy (TEM) images of 300 AuNRs (Figure 1A) the as-prepared particles have an average length of 44 ± 4 nm and an average width of 11 ± 2 nm
Summary
Multifunctional imaging and combined multimodal therapy strategies are very promising in cancer theranostics [1,2]. This platform demonstrates three distinct features: (1) targeting of nanocomposites with folic acid leads to enhanced cellular uptake by folate-positive cancer cells compared with PEGcoated nanorods; (2) the high loading with rhodamine 123 makes the nanoparticles suitable for cell imaging with a simple fluorescent microscope; (3) through using NIR-mediated photothermal therapy the cancer cells can be killed with a high efficiency.
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