1064-nm-resonant gold nanorods for photoacoustic theranostics within permissible exposure limits

Therapeutic and diagnostic methods based on photomechanical effects are attracting much current attention in contexts as oncology, cardiology and vascular surgery, for such applications as photoacoustic imaging or microsurgery. Their underlying mechanism is the generation of ultrasound or cavitation from the interaction of short optical pulses with endogenous dyes or targeted contrast agents. Among the latter, gold nanorods are outstanding candidates, but their use has mainly been reported for photoacoustic imaging and photothermal treatments. Conversely, much less is still known about their value as a precision tool for photomechanical manipulations, such as to impart local damage with high spatial resolution through the expansion and collapse of microbubbles. Here, we address the feasibility of gold nanorods exhibiting a distribution of surface plasmon resonances between about 900 to above 1100 nm as a contrast agent for photoacoustic theranostics. After testing their cytotoxicity and cellular uptake, we discuss their photostability and use to mediate cavitation and the photomechanical destruction of targeted cells. We find that the choice of a plasmonic band peaking around 1064 nm is key to enhance the translational potential of this approach. With respect to the standard alternative of 800 nm, at 1064 nm, relevant regulations on optical exposure are less restrictive and the photonic technology is more mature.

Efficacy of biofeedback treatment compared with drug therapy in hypertensive patients

To assess the ability of biofeedback (BFB) in controlling hypertension a study was made of 40 hypertensive patients selected by means of the cardiovascular response to an arithmetic test. The patients were divided into four treatment groups: 10 patients were treated with diuretic therapy (D-T), 10 with beta-blocker therapy (Bb-T), 10 with BFB treatment, while 10 had no treatment at all (N-T). The BFB treatment consisted of 36 sittings where patients were requested to control muscular contraction, peripheric temperature and heart rate (HR) by means of a correlated acoustic signal. The results for blood pressure and HR reductions were compared during a 12-month follow-up period. The results for systolic blood pressure, diastolic blood pressure and HR indicate the efficacy of BFB for selected patients and suggest the possibility of using BFB treatment in the first stages of suspected neurogenic hypertension.