Rational approach to design gold nanoparticles for photothermal therapy: the effect of gold salt on physicochemical, optical and biological properties.

Among the unique characteristics associated to gold nanoparticles (AuNPs) in biomedicine, their ability to convert light energy into heat opens ventures for improved cancer therapeutic options, such as photothermal therapy (PTT). PTT relies on the local hyperthermia of tumor cells upon irradiation with light beams, and the association of AuNPs with radiation within the near infrared (NIR) range constitutes an advantageous strategy to potentially improve PTT efficacy. Herein, it was explored the effect of the gold salt on the AuNPs' physicochemical and optical properties. Mostly spherical-like negatively charged AuNPs with variable sizes and absorbance spectra were obtained. In addition, photothermal features were assessed using in vitro phantom models. The best formulation showed the ability to increase their temperature in aqueous solution up to 19 °C when irradiated with a NIR laser for 20 min. Moreover, scanning transmission electron microscopy confirmed the rearrangement of the gold atoms in a face-centered cubic structure, which further allowed to calculate the photothermal conversion efficiency upon combination of theoretical and experimental data. AuNPs also showed local retention after being locally administered in in vivo models. These last results obtained by computerized tomography allow to consider these AuNPs as promising elements for a PTT system. Moreover, AuNPs showed high potential for PTT by resulting in in vitro cancer cells' viability reductions superior to 70 % once combine with 5 min of NIR irradiation.

Relaxation and guided imagery program in patients with breast cancer undergoing radiotherapy is not associated with neuroimmunomodulatory effects.

OBJECTIVE: Treatment of breast cancer is usually associated with significant psychological stress. In this study, we examined the effects of relaxation and visualization therapy (RVT) on psychological distress, cortisol levels, and immunological parameters of breast cancer patients undergoing radiotherapy. METHODS: Participants were randomly assigned to either the experimental (n=20) who underwent group RVT for 24 consecutive days or control group (n=14) who were on radiotherapy only. Psychological scores (stress, anxiety, and depression) were measured by structured clinical interviews. Salivary cortisol was assessed along the day. Lymphocytes were isolated and cultured to measure T-cell proliferation and sensitivity to glucocorticoids (GCs). RESULTS: RVT was effective to reduce stress, anxiety, and depression scores (all P<.05). However, cortisol levels as well as proliferation remained unchanged following RVT. Although T cells of experimental group were more sensitive to GCs than cells of controls at baseline, no changes were noted following RVT. Cortisol levels were positively correlated to anxiety and depression scores and inversely correlated to T-cell proliferation and sensitivity to GCs. CONCLUSION: We conclude that the psychological intervention was capable to attenuate the emotional distress presented during radiotherapy treatment. A longer RVT or worse psychological morbidity at baseline may be necessary to translate psychological into biological changes.