Purpose: Gold nanoparticles are one of the fields of nanomedicines in cancer by photothermal therapy. Herein, we report gold nanoclusters loaded albumin nanoparticles (GNC/BSA-NPs). Additionally, it can be used to diagnose and identify of cancer through fluorescence overcoming quenching of gold nanoparticles. And we verified the characterization of GNC/BSA-NPs and effect of photothermal therapy.
Methods: Gold nanoparticles were fabricated by reduction HAuCl4 using reducing agent sodium citrate and NaBH4. Using this made gold nanoparticles, we made the GNC/BSA-NPs in 2 steps. The first step is to make the agglomerated AuNPs that is also called as gold nanoclusters. In this step, AuNPs solution were concentrated to 6 mg/mL by centrifugation with the Amicon® 30K ultra centrifugal filters. Next, AuNPs solution (6 mg/mL) was dropped into the BSA solution dissolved in 100 mM PB solution (pH 8.0) under 200 rpm. Second step is to enclose gold nanoclusters into the albumin nanoparticle via desolvation process. Gold nanocluster was centrifuged at 14,500 rpm for 10 min twice and discarded the supernatant fraction which is the unreacted BSA solution. And, deposited gold nanoclusters were resuspended with Cy 5.5 labeled BSA solution. After 5 min, ethanol was dropwised into this solution at 1 mL/min. Finally, 1 μL of 50% Glutaraldehyde was added and reacted overnight under 200 rpm.
Results: The size of spherical GNC BSA-NPs was about ~120nm. The zeta potential of GNC BSA-NPs, GNC and GNP was -52.2 ± 5.2 mV, -42.5 ± 0.3 mV and -28.5 ± 3.7 mV, respectively. When irradiation under 808 nm NIR laser, the temperature of GNC BSA-NPs, GNC and AuNP raised up to 70.7 ℃, 67.4 ℃ and 34.6 ℃, respectively. When injected the GNC BSA-NPs in the mice by tail vein and irradiated 808 nm NIR laser, the temperature of local tumor raised up to > 50 ℃. The optical in vivo imaging system detected the fluorescence of Cy5.5 to evaluate the targeting of GNC BSA-NPs to tumor in mice. On the MTT and Live-dead assay, the GNC BSA-NPs had photothermal effect and cytotoxicity in a HCT116 cell. In addition, it was found that the GNC BSA-NPs is internalized in HCT116 cell by CLSM.
Conclusion: In short, we fabricated a unique fluorescent albumin nanoparticles loading gold nanoclusters. These nanoparticles showed photothermal effect in tumor cells and identification of targeting tumor through fluorescence. We believe that gold nanoclusters loaded albumin nanoparticles would be a good delivery platform for treating colon cancers.
Bohyung Seo– Sungkyunkwan University
Sanghyun Park– Sungkyunkwan University
Sung Soo Kim– Graduate Student, SungKyunKwan University, Suwon-si, Kyonggi-do
Yu Seok Youn– Professor, Sungkyunkwan University