Magnetic gold-nanorod/ PNIPAAmMA nanoparticles for dual magnetic resonance and photoacoustic imaging and targeted photothermal therapy.

Nanomedicine can provide a multi-functional platform for image-guided diagnosis and treatment of cancer. Although gold nanorods (GNRs) have been developed for photoacoustic (PA) imaging and near infra-red (NIR) photothermal applications, their efficiency has remained limited by low thermal stability. Here we present the synthesis, characterization, and functional evaluation of non-cytotoxic magnetic polymer-modified gold nanorods (MPGNRs), designed to act as dual magnetic resonance imaging (MRI) and PA imaging contrast agents. In addition, their high magnetization allowed MPGNRs to be actively localized and concentrated by targeting with an external magnet. Finally, MPGNRs significantly enhanced the NIR-laser-induced photothermal effect due to their increased thermal stability. MPGNRs thus provide a promising new theranostic platform for cancer diagnosis and treatment by combining dual MR/PA imaging with highly effective targeted photothermal therapy.

Thermal damage potential during hip resurfacing in osteonecrosis of the femoral head: an experimental study.

Hip resurfacing arthroplasty has become an attractive treatment option for young, active patients with femoral head necrosis. However, little information is available about the potential thermal damage to the remaining femoral head when a cemented component is used. We used an experimental model to measure the temperature profile at the cement-bone interface during hip resurfacing. We compared four simulated lesion sizes-15, 25, 33, and 50%-of the femoral head, and a control group with no cystic lesion. Temperatures were measured with the specimens in a 37 degrees C saline bath or with copious pulsed lavage. With specimens tested in the bath, peak temperatures were higher, and durations of temperatures above 50 degrees C were longer, in femoral heads with necrotic lesions (88.8 +/- 7.5 degrees C; 17.6 +/- 1.1 min for a 15% lesion; 96.2 +/- 7.2 degrees C; 22.86 +/- 1.3 min for a 25% lesion; 99.7 (c) 200 +/- 9.4 degrees C; 28.6 +/- 2.0 min for a 33% lesion; and 97.2 +/- 4.2 degrees C; 35.6 +/- 2.4 min for a 50% lesion) than those in the control group (65.8 +/- 4.9 degrees C; 10.0 +/- 1.3 min). The larger the cement-filled cysts, the longer the temperatures remained above 50 degrees C. Although copious lavage reduced the temperature profile in each group, the temperatures remained above 50 degrees C for 7 to 17 min in specimens with necrotic cysts. The measured temperatures during surface replacement are sufficiently high in magnitude and long in duration to cause thermal damage to the remaining bone in femoral heads with preexisting necrotic lesions. Hip resurfacing for femoral head necrosis should be performed with caution.