Synthesis, optical properties and photherapy applications of gold nanostars

Cancer Treatment Using Different Shapes of Gold-Based Nanomaterials in Combination with Conventional Physical Techniques

The conventional methods of cancer treatment and diagnosis, such as radiotherapy, chemotherapy, and computed tomography, have developed a great deal. However, the effectiveness of such methods is limited to the possible failure or collateral effects on the patients. In recent years, nanoscale materials have been studied in the field of medical physics to develop increasingly efficient methods to treat diseases. Gold nanoparticles (AuNPs), thanks to their unique physicochemical and optical properties, were introduced to medicine to promote highly effective treatments. Several studies have confirmed the advantages of AuNPs such as their biocompatibility and the possibility to tune their shapes and sizes or modify their surfaces using different chemical compounds. In this review, the main properties of AuNPs are analyzed, with particular focus on star-shaped AuNPs. In addition, the main methods of tumor treatment and diagnosis involving AuNPs are reviewed.

The multimodal effect of Photothermal/Photodynamic/Chemo therapies mediated by Au-CoFe2O4 @Spiky nanostructure adjacent to mitoxantrone on breast cancer cells

BACKGROUND

Conventional cancer treatments are associated with a number of limitations, including non-selectivity, toxicity and multidrug resistance, so new nanotechnologies are being developed forcancer diagnosis and therapy. Phototherapy approach based on nanotechnology is a hopeful strategy to overcome these problems. Photothermal (PTT) and photodynamic therapies (PDT), in addition to having non-invasive properties, are known as promising methods for treatment of tumors. In this study, CoFe₂O₄ theranostic magnetic nanoparticles coated with spiky gold nanoparticles were designed and synthesized and its photothermal effects were evaluated in combination with the photodynamic and chemotherapeutic effects of mitoxantrone (MTX) under in vitro conditions.

METHODS AND MATERIALS

At first, CoFe₂O₄ @Spiky Au nanostructure was synthesized and after its characterization, cytotoxicity of MTX, CoFe₂O₄ @ Spiky Au (MGNS) and CoFe₂O₄ @ Au were determined on MDA-MB-231 cell line. Then, the concentrations required for inducing 50% cell death (IC₅₀) and appropriate concentration for this study was obtained. Cells were irradiated by an 808 nm laser and a non-synchronous light source at 670 nm at the separate groups. The viability of treated cells was determined via MTT test 48 h after treatment.

RESULTS

In the groups receiving energy density (5-40) J/cm², at the lower laser dose an increase in cell survival was observed (P < 0.05) and then cell survival was decreased (P < 0.05). In the groups receiving non-coherent light (2-18 J/cm²) from the beginning, a decreasing trend in cell survival is observed.

CONCLUSION

The overlap of the emission spectrum of the light source and the absorption spectrum of the nanostructure amplified the cell death. Similar to the Hormesis model reported for ionizing radiation effects, at low light doses with the bio-phasic response dose model, increased cell survival and proliferation can be expected.

A Review on Gold Nanotriangles: Synthesis, Self-Assembly and Their Applications

Gold nanoparticles (AuNPs) with interesting optical properties have attracted much attention in recent years. The synthesis and plasmonic properties of AuNPs with a controllable size and shape have been extensively investigated. Among these AuNPs, gold nanotriangles (AuNTs) exhibited unique optical and plasmonic properties due to their special triangular anisotropy. Indeed, AuNTs showed promising applications in optoelectronics, optical sensing, imaging and other fields. However, only few reviews about these applications have been reported. Herein, we comprehensively reviewed the synthesis and self-assembly of AuNTs and their applications in recent years. The preparation protocols of AuNTs are mainly categorized into chemical synthesis, biosynthesis and physical-stimulus-induced synthesis. The comparison between the advantages and disadvantages of various synthetic strategies are discussed. Furthermore, the specific surface modification of AuNTs and their self-assembly into different dimensional nano- or microstructures by various interparticle interactions are introduced. Based on the unique physical properties of AuNTs and their assemblies, the applications towards chemical biology and sensing were developed. Finally, the future development of AuNTs is prospected.

Shape-dependent gold nanoparticle interactions with a model cell membrane

Customizable gold nanoparticle platforms are motivating innovations in drug discovery with massive therapeutic potential due to their biocompatibility, stability, and imaging capabilities. Further development requires the understanding of how discrete differences in shape, charge, or surface chemistry affect the drug delivery process of the nanoparticle. The nanoparticle shape can have a significant impact on nanoparticle function as this can, for example, drastically change the surface area available for modifications, such as surface ligand density. In order to investigate the effects of nanoparticle shape on the structure of cell membranes, we directly probed nanoparticle-lipid interactions with an interface sensitive technique termed sum frequency generation (SFG) vibrational spectroscopy. Both gold nanostars and gold nanospheres with positively charged ligands were allowed to interact with a model cell membrane and changes in the membrane structure were directly observed by specific SFG vibrational modes related to molecular bonds within the lipids. The SFG results demonstrate that the +Au nanostars both penetrated and impacted the ordering of the lipids that made up the membrane, while very little structural changes to the model membrane were observed by SFG for the +Au nanospheres interacting with the model membrane. This suggests that the +Au nanostars, compared to the +Au nanospheres, are more disruptive to a cell membrane. Our findings indicate the importance of shape in nanomaterial design and provide strong evidence that shape does play a role in defining nanomaterial-biological interactions.

Recent progress in the applications of gold-based nanoparticles towards tumor-targeted imaging and therapy

Cancer death rate remains high all over the world, scientists are paying increasing attention to meet the requirements for precise diagnosis and therapy. Therefore, early diagnosis and active treatment can effectively improve the five-year survival rate of patients. In recent years, gold-based nanomaterials have received increasing attention in medical fields due to their excellent biocompatibility, low toxicity and unique properties. In addition, because of the inherent nature of gold nanomaterials including for computed tomography (CT), fluorescence/optical imaging (FI/OI), surface enhanced Raman spectroscopy imaging (SERS), photoacoustic imaging (PAI) and photothermal therapy (PTT), various gold nanomaterials were developed as theranostic nanoplatforms. In this review, we summarized the latest developments of nanomaterials in imaging and combined therapy, and the prospects for the future application of gold-based theranostic nanoplatforms were also proposed.

We summarize the latest developments of gold nanomaterials in imaging and combined therapy as well as prospects for the future application of gold-based theranostic nanoplatforms.