High And Low Molecular Weight Hyaluronic Acid-Coated Gold Nanobipyramids For Photothermal Therapy

Backgrounds and Objective:Breast cancer is one of the most common malignant tumors in women,and about 61%of the patients in the United States can be diagnosed early and correctly.Breast cancer is a serious threat to women's health,and surgery,chemotherapy,endocrine therapy and adjuvant radiotherapy are the main treatments of breast cancer currently.However,with the relatively ideal treatment results,surgical trauma,cancer resistance and recurrence problems constantly plagued the breast cancer patients,and at present,the focus of clinical work is still to find the effective treatment of breast cancer,good targeting and less adverse reactions.The target accumulation effect of gold nanoparticles in tumor sites and the spatial light limitation of photothermal therapy have made the gold nanomaterials with a good application prospect in the field of tumor therapy.The local surface plasmon resonance(LSPR)of gold nanobipyramids(GBPs)is stronger than other gold nanoparticles,and the absorption peaks are narrower,which can more effectively convert light into thermal energy.As the CD44 receptors on the surface of most tumor cells are the ideal receptors of hyaluronic acid(HA),the nanoparticles based on HA have been widely used in CD44 positive solid tumors.Combining photothermal therapy of GBPs with targeting therapy of HA,and constructing an integrative system based on HA nanoparticles to evaluate the tumor targeting,tumor progression and treatment effect,which is important for optimizing the treatment plan,reducing the local recurrence and alleviating the adverse reactions.Methods:In this work,we first constructed two new nanoparticles(GBPs@l-HA and GBPs@h-HA)by coating different molecular weight HA(380 kDa,102 kDa)on the GBP surface by electrostatic interaction.The characterization of the GBPs@l-HA and GBPs@h-HA fabrication was investigated by Transmission Electron Microscope(TEM),UV-vis spectroscopy,dynamic light scattering(DLS)and a Nano-Zetasizer(Zeta).Inductively coupled plasma atomic emission spectrometry(ICP-AES)was chosen to evaluate the cellular uptake of GBPs@l-HA and GBPs@h-HA by calculating the intracellular concentration of Au+.MTT assays were performed to detect the cell viability in HEK 293T cells and MDA-MB-231/Luc cells to confirm the toxicity and therapeutic efficiency of GBPs@l-HA and GBPs@h-HA.Tumor-targeting therapeutic performance and biocompatibility of the GBPs@h-HA and GBPs@l-HA were elucidated under 808-nm NIR irradiation in MDA-MB-231/Luc xenografts.Results:The molecular weight of HA varies with the chain length of the polymer,ranging from 50 kDa to 20000 kDa.The GBPs surface had a large amount of positive charge and was tightly connected with negatively charged HA by electrostatic interaction,which could enhance the stability of GBPs in aqueous solution and address the clinical inconvenience.The grafting density of GBPs@l-HA and GBPs@h-HA were 13.22 and 4.77,respectively,which showed good conjugation efficiency.The absorption spectra of GBPs@l-HA or GBPs@h-HA were detected in various solutions for different time periods,and the LSPR bands of GBPs@l-HA and GBPs@h-HA and their intensities remained unchanged after standing for 7 days,indicating their excellent stability in aqueous solution and avoiding adverse effect effectively.ICP-AES was chosen to evaluate the cellular uptake of GBPs@l-HA and GBPs@h-HA,and GBPs@h-HA(0.41 ± 0.1 ng Au per ng protein)exhibited more uptake than GBPs@l-HA incubated(0.1185±0.0626 ng Au per ng protein).GBPs@l-HA or GBPs@h-HA at various concentrations(from 1.875 mg/L to 15 mg/L)were incubated with HEK 293T cells for 24 h.Then,MTT assays revealed that the cell viability remained greater than 84%at a nanoparticle concentration of 15 mg/L,and no obvious morphology change was captured using the Olympus microscope at 4 h and 24 h,suggesting the low toxicity and excellent biocompatibility of GBPs@l-HA and GBPs@h-HA.Upon 808 nm laser irradiation,as a result of the accumulation of heat produced by GBPs,the photothermal effect was gradually enhanced and the photothermal efficiency of GBPs@h-HA was higher than that of GBPs@l-HA,reflecting the therapeutic advantage of high molecular weight HA.GBPs@h-HA can effectively kill MDA-MB-231/Luc breast cancer cells and inhibit tumor growth in tumor bearing nude mice,and its therapeutic effect is significantly better than that of GBPs@l-HA group.Conclusions:The cellular uptake and therapeutic efficacy of gold nanobipyramids coated by high(380 kDa)was superior than that of gold nanobipyramids coated by low(102 kDa)molecular weight HA.ICP studies showed GBPs@h-HA possessed a higher cellular uptake in MDA-MB-231/Luc breast cancer cells when compared with GBPs@l-HA and were able to enhance photothermal therapeutic efficacy both in vitro and in vivo.In addition,both GBPs@h-HA and GBPs@l-HA have good biocompatibility,which has a certain prospect in biomedical research and clinical transformation in the future.