Modifying the mechanical properties of gold nanorods by copper doping and triggering their cytotoxicity with ultrasonic wave

Highly localized, efficient, and rapid photothermal therapy using gold nanobipyramids for liver cancer cells triggered by femtosecond laser

In this study, the photothermal effect and up-conversion florescence imaging effect of gold nanobipyramids in liver cancer cells are investigated theoretically and experimentally to explore the photothermal ablation tumor therapy with higher photothermal conversion efficiency, shorter laser action time, smaller action range and lower laser power. The small-size gold nanobipyramids with good biocompatibility and infrared absorption peak located in the first biological window are synthesized. Femtosecond laser is focused on the nanobipyramids clusters in cells and the cells die after being irradiated for 20 s at a power as low as 3 mW. In contrast, the control cells die after irradiation with 30 mW laser for 3 min. The theoretical simulation results show that: under femtosecond laser irradiation, the local thermal effect of gold nanoclusters is produced in the range of hundreds of square nanometers and the temperature rises by 516 °C in 106 picoseconds. This therapy reduces the treatment time to seconds level, and the treatment range to square micrometer level, the power to milliwatt level. In this treatment, cells die by apoptosis rather than necrosis, which reduces inflammation. This result opens up a new way to develop photothermal ablation therapy with less side effects and more minimally invasive.

Gold Nanorods for Drug and Gene Delivery: An Overview of Recent Advancements

Over the past few decades, gold nanomaterials have shown great promise in the field of nanotechnology, especially in medical and biological applications. They have become the most used nanomaterials in those fields due to their several advantageous. However, rod-shaped gold nanoparticles, or gold nanorods (GNRs), have some more unique physical, optical, and chemical properties, making them proper candidates for biomedical applications including drug/gene delivery, photothermal/photodynamic therapy, and theranostics. Most of their therapeutic applications are based on their ability for tunable heat generation upon exposure to near-infrared (NIR) radiation, which is helpful in both NIR-responsive cargo delivery and photothermal/photodynamic therapies. In this review, a comprehensive insight into the properties, synthesis methods and toxicity of gold nanorods are overviewed first. For the main body of the review, the therapeutic applications of GNRs are provided in four main sections: (i) drug delivery, (ii) gene delivery, (iii) photothermal/photodynamic therapy, and (iv) theranostics applications. Finally, the challenges and future perspectives of their therapeutic application are discussed.

Development of gold nanorods for cancer treatment

There has been growing interest in the application of gold nanorods (GNRs) to tumor therapy due to the unique properties they possess. In the past, GNRs were not used in clinical treatments as they lacked stability in vivo and were characterized by potential toxicity. Despite these issues, the significant potential for utilizing GNRs to conduct safe and effective treatments for tumors cannot be ignored. Therefore, it remains crucial to thoroughly investigate the mechanisms behind the toxicity of GNRs in order to provide the means of overcoming obstacles to its full application in the future. This review presents the toxic effects of GNRs, the factors affecting toxicity and the methods to improve biocompatibility, all of which are presently being studied. Finally, we conclude by briefly discussing the current research status of GNRs and provide additional perspective on the challenges involved along with the course of development for GNRs in the future.

Cell Imaging Using Two-Photon Excited CdS Fluorescent Quantum Dots Working within the Biological Window

In recent years, two-photon excited semiconductor quantum dots (QDs) have been the subject of intense investigation due to their long excitation wavelength which helps to achieve deeper penetration and higher image resolution in optical bioimaging. In this paper, water-soluble CdS QDs were synthesized using a hydrothermal method and applied to human liver hepatocellular carcinoma (HepG2) cells. The first-principles calculation suggested that the S-rich defected structure contributes to a narrower band gap compared to the pristine structure. The resulting fluorescence wavelength was significantly red shifted, which was attributed to the deep defect states emission. The large Stokes shifts (> 200 nm) of the QDs can eliminate the possible cross-talk between the excitation light and the emission light. Two-photon induced red fluorescence emission can avoid overlapping with the autofluorescence emission of biological samples. The uptake and cell viability measurements of the HepG2 cells showed a good biocompatibility and a low toxicity of CdS QDs. Two-photon excited scanning microscopy images revealed that the HepG2 cells incubated with CdS QDs emitted bright red upconversion fluorescence and the fluorescence brightness was 38.2 times of that of the control group. These results support CdS QDs as a good candidate for application in cellular imaging.

A Novel Fast Photothermal Therapy Using Hot Spots of Gold Nanorods for Malignant Melanoma Cells

In this paper, the plasmon resonance effects of gold nanorods was used to achieve rapid photothermal therapy for malignant melanoma cells (A375 cells). After incubation with A375 cells for 24 h, gold nanorods were taken up by the cells and gold nanorod clusters were formed naturally in the organelles of A375 cells. After analyzing the angle and space between the nanorods in clusters, a series of numerical simulations were performed and the results show that the plasmon resonance coupling between the gold nanorods can lead to a field enhancement of up to 60 times. Such high energy localization causes the temperature around the nanorods to rise rapidly and induce cell death. In this treatment, a laser as low as 9.3 mW was used to irradiate a single cell for 20 s and the cell died two h later. The cell death time can also be controlled by changing the power of laser which is focused on the cells. The advantage of this therapy is low laser treatment power, short treatment time, and small treatment range. As a result, the damage of the normal tissue by the photothermal effect can be greatly avoided.