Plasmon-Based Biofilm Inhibition on Surgical Implants.

The insertion of an implant in the body of a patient raises the risk of a posterior infection and formation of a biofilm, which can have critical consequences on the patient's health and be associated with a high sanitary cost. While antibacterial agents can be used to prevent the infection, such a strategy is time-limited and causes bacteria resistance. As an alternative to biochemical approaches, we propose here to use light-induced local hyperthermia with plasmonic nanoparticles. This strategy is implemented on surgical meshes, extensively used in the context of hernia repairing, one of the most common general surgeries. Surgical meshes were homogeneously coated with gold nanorods designed to efficiently convert near-infrared light into heat. The modified mesh was exposed to a biofilm of Staphylococcus aureus ( S. aureus) bacteria before being treated with a train of light pulses. We systematically study how the illumination parameters, namely fluence, peak intensity and pulse length, influence the elimination of attached bacteria. Additionally, fluorescence confocal microscopy provides us some insight on the mechanism involved in the degradation of the biofilm. This proof-of-principle study opens a new set of opportunities for the development of novel disinfection approaches combining light and nanotechnology.

White and Brightly Colored 3D Printing Based on Resonant Photothermal Sensitizers.

The use of photothermal sensitizers to facilitate the sintering of polymer powders is rapidly becoming a pivotal additive manufacturing technology, impacting multiple sectors of industry. However, conventional carbon-based sensitizers can only produce black or gray objects. To create white or colorful prints with this method, visibly transparent equivalents are needed. Here, we address this problem by designing resonant photothermal sensitizers made of plasmonic nanoparticles that strongly absorb in the near-infrared, while only minimally interacting with visible light. Gold nanorods were coated with silica before being mixed with polyamide powders to create stable colorful nanocomposite powders. At resonance, these composites showed greatly improved light-to-heat conversion compared with equivalent composites using the industry standard carbon black as a sensitizer and could be sintered using low-power light sources. Furthermore, they appear much whiter and can produce brightly colored 3D objects when mixed with dyes. Our results open a new route to utilize plasmonic nanoparticles to produce colorful and functional 3D-printed objects.

Experimental demonstration of a cognitive quality of transmission estimator for optical communication systems.

The impact of physical layer impairments in optical network design and operation has received significant attention in the last years, thereby requiring estimation techniques to predict the quality of transmission (QoT) of optical connections before being established. In this paper, we report on the experimental demonstration of a case-based reasoning (CBR) technique to predict whether optical channels fulfill QoT requirements, thus supporting impairment-aware networking. The validation of the cognitive QoT estimator is performed in a WDM 80 Gb/s PDM-QPSK testbed, and we demonstrate that even with a very small and not optimized underlying knowledge base, it achieves between 79% and 98.7% successful classifications based on the error vector magnitude (EVM) parameter, and approximately 100% when the classification is based on the optical signal to noise ratio (OSNR).

Treatment of Hepatic Fibrosis in Mice Based on Targeted Plasmonic Hyperthermia.

Liver fibrosis is a major health problem with multiple associated complications, which, to date, has no effective treatment. Hepatic stellate cells are the main responsible cells for fibrosis formation; upon their activation, excess accumulation of extracellular matrix and collagen deposits occurs. The mitogen platelet-derived growth factor (PDGF) and its receptor ß (PDGFRß) play a major role in hepatic stellate cells activation and are, therefore, promising targets for antifibrotic therapies. Gold nanorods hold great potential for diseased liver treatments, since their passive hepatic accumulation enhances active targeting strategies, hence increasing therapeutic efficiency. In addition, gold nanorods have photothermal properties that, combined with specific cell delivery, can be exploited to induce localized near-infrared light-mediated thermal ablation. Here, we demonstrate that gold nanorods coated with anti-PDGFRß specifically target activated hepatic stellate cells in vivo. Additionally, gold nanorods-PDGFRß-mediated photothermal therapy decreases fibrosis, hepatic inflammation, and hepatocyte injury in the experimental model of CCl4-induced liver fibrosis in mice.

Non-invasive and quantitative in vivo monitoring of gold nanoparticle concentration and tissue hemodynamics by hybrid optical spectroscopies.

Owing to their unique combination of chemical and physical properties, inorganic nanoparticles show a great deal of potential as suitable agents for early diagnostics and less invasive therapies. Yet, their translation to the clinic has been hindered, in part, by the lack of non-invasive methods to quantify their concentration in vivo while also assessing their effect on the tissue physiology. In this work, we demonstrate that diffuse optical techniques, employing near-infrared light, have the potential to address this need in the case of gold nanoparticles which support localized surface plasmons. An orthoxenograft mouse model of clear cell renal cell carcinoma was non-invasively assessed by diffuse reflectance and correlation spectroscopies before and over several days following a single intravenous tail vein injection of polyethylene glycol-coated gold nanorods (AuNRs-PEG). Our platform enables to resolve the kinetics of the AuNR-PEG uptake by the tumor in quantitative agreement with ex vivo inductively coupled plasma mass spectroscopy. Furthermore, it allows for the simultaneous monitoring of local tissue hemodynamics, enabling us to conclude that AuNRs-PEG do not significantly alter the animal physiology. We note that the penetration depth of this current probe was a few millimeters but can readily be extended to centimeters, hence gaining clinical relevance. This study and the methodology presented here complement the nanomedicine toolbox by providing a flexible platform, extendable to other absorbing agents that can potentially be translated to human trials.

Quantification of gold nanoparticle accumulation in tissue by two-photon luminescence microscopy.

Nanomedicine has emerged as a promising strategy to address some of the limitations of traditional biomedical sensing, imaging and therapy modalities. Its applicability and efficacy are, in part, hindered by the difficulty in both controllably delivering nanoparticles to specific regions and accurately monitoring them in tissue. Gold nanoparticles are among the most extensively used inorganic nanoparticles which benefit from high biocompatibility, flexible functionalization, strong and tunable resonant absorption, and production scalability. Moreover, their capability to enhance optical fields at their plasmon resonance enables local boosting of non-linear optical processes, which are otherwise very inefficient. In particular, two-photon induced luminescence (TPL) in gold offers high signal specificity for monitoring gold nanoparticles in a biological environment. In this article, we demonstrate that TPL microscopy provides a robust sub-micron-resolution technique able to quantify accumulated gold nanorods (GNRs) both in cells and in tissues. First, the temporal accumulation of GNRs with two different surface chemistries was measured in 786-O cells during the first 24 hours of incubation, and at different nanoparticle concentrations. Subsequently, GNR accumulation in mice, 6 h and 24 hours after tail vein injection, was quantified by TPL microscopy in biopsied tissue from kidney, spleen, liver and clear cell renal cell carcinoma (ccRCC) tumors, in good agreement with inductively coupled mass spectroscopy. Our data suggest that TPL microscopy stands as a powerful tool to understand and quantify the delivery mechanisms of gold nanoparticles, highly relevant to the development of future theranostic medicines.

Optimum morphology of gold nanorods for light-induced hyperthermia.

Owing to their unique chemical and physical properties, colloidal gold nanoparticles have prompted a wide variety of biocompatible nano-agents for cancer imaging, diagnosis and treatment. In this context, biofunctionalized gold nanorods (AuNRs) are promising candidates for light-induced hyperthermia, to cause local and selective damage in malignant tissue. Yet, the efficacy of AuNR-based hyperthermia is highly dependent on several experimental parameters; in particular, the AuNR morphology strongly affects both physical and biological processes. In the present work, we systematically study the influence of different structural parameters like the AuNR aspect ratio, length and molecular weight on in vitro cytotoxicity, cellular uptake and heat generation efficiency. Our results enable us to identify the optimum AuNR morphology to be used for in vivo hyperthermia treatment.

Two-color dark-field (TCDF) microscopy for metal nanoparticle imaging inside cells.

Noble metal nanoparticles (NPs) supporting localized surface plasmon resonances are widely used in the context of biotechnology as optical and absorption contrast agents with great potential applicability to both diagnostics and less invasive therapies. In this framework, it is crucial to have access to simple and reliable microscopy techniques to monitor the NPs that have internalized into cells. While dark field (DF) microscopy takes advantage of the enhanced NP scattering at their plasmon resonance, its use in cells is limited by the large scattering background from the internal cell compartments. Here, we report on a novel two-color dark field microscopy that addresses these limitations by significantly reducing the cell scattering contribution. We first present the technique and demonstrate its enhanced contrast, specificity and reliability for NP detection compared to a standard optical dark field. We then demonstrate its potential suitability in two different settings, namely wide-field parallel screening of circulating cells in microfluidic chips and high-resolution tracking of internalized NPs in cells. These proof of principle experiments show a promising capability of this approach with possible extension to other kinds of targeted systems like bacteria and vesicles.

Percutaneous fixation of displaced proximal humeral fractures: indications based on the correlation between clinical and radiographic results.

We evaluated 74 patients with displaced proximal humeral fractures (mean age, 70.9 years) treated with closed reduction and percutaneous pinning. Fractures were classified radiographically following Neer's system, and the quality of reduction was assessed according to Kristiansen and Kofoed. Patients were also evaluated clinically with the Constant scale. Overall, the reduction was good in 72% of fractures, but the probability of obtaining a satisfactory reduction of displaced tuberosities was significantly lower in comparison to the humeral head. Four-part fractures obtained the worst radiographic results. The mean Constant scores were 65.8 +/- 18 points for the injured shoulder and 79.5 +/- 9.1 points for the opposite shoulder. Clinical results correlated with the quality of reduction. Closed reduction and percutaneous pinning should be reserved for 2-part fractures, but the technique can also be used in 3-part fractures in elderly patients, in whom an incomplete reduction can yield satisfactory clinical results.

Rotator cuff impingement due to enchondroma of the acromion.

We report the case of a patient with a long standing clinical history of subacromial impingement, in which plain radiographs and CT-scan revealed a well-circumscribed lucent lesion expanding the undersurface of the acromion. MRI showed the subacromial fat to be completely obliterated and the infraspinatus tendon deformed due to compression by a mass localised at the acromion. The acromial lesion was curetted, and histopathologic analysis was consistent with the diagnosis of enchondroma. Tumours located in the coracoacromial arch have been very rarely reported as a cause of subacromial impingement. To the best of our knowledge, this is the first description of subacromial impingement secondary to acromial enchondroma.

Percutaneous vertebroplasty: functional improvement in patients with osteoporotic compression fractures.

STUDY DESIGN: Prospective, double-cohort study. OBJECTIVE: To evaluate conservative and percutaneous vertebroplasty (PV) management of osteoporotic vertebral fractures. SUMMARY OF BACKGROUND DATA: PV is an elective alternative to conservative management for the treatment of a painful osteoporotic vertebral fracture. METHODS: We performed a prospective study consisting of 101 consecutive patients who underwent PV and 27 patients who refused PV treatment and were managed conservatively. We used a data evaluation and outcomes system that was developed to evaluate the outcomes of surgical intervention. RESULTS: Patients that elected for PV as a treatment of their fractures had significantly more pain and functional impairment before the procedure than the patients of the conservative group (P < 0.001). The pain, functional, and general health scores of the PV group were improved from the preoperative mean values (P < 0.001) in all postoperative periods. Compared with the conservative treatment group, there was a significant difference at month 3. However, no statistical differences on function were observed between these groups at 6 months and 1 year posttreatment. CONCLUSIONS: PV demonstrated a rapid and significant relief of pain and improved the quality of life. PV election for treatment of painful osteoporotic vertebral fracture after 6 weeks of conservative treatment was based on pain and functional impairment.

Predictors of outcomes of percutaneous vertebroplasty for osteoporotic vertebral fractures.

STUDY DESIGN: Retrospective review of all percutaneous vertebroplasties performed in the authors' institution from November 1994 to June 2002. OBJECTIVE.: To determine the factors affecting the outcome of percutaneous vertebroplasty for the treatment of persistent painful osteoporotic fractures. SUMMARY OF BACKGROUND DATA: Percutaneous vertebroplasty is an efficient procedure to treat pain due to osteoporotic vertebral fracture. However, the patient population that is most likely to benefit from this procedure is uncertain, and the inclusion and exclusion criteria for an ideal candidate have varied widely in the literature. METHODS: A retrospective review of 278 percutaneous vertebroplasty procedures for osteoporotic fractures at 423 levels was performed. Sociodemographic, clinical, radiologic, and procedural data were analyzed as parameters for prognosis significance by univariate and multivariate analysis with logistic regression to estimate the strength of influence of each variable. RESULTS: The presence of two or less symptomatic vertebrae (P < 0.03), the American Society of Anesthesiologists status I (P < 0.001), the presence of signal changes on magnetic resonance imaging (P < 0001), and the collapse of the vertebral body less than 70% (P < 0.001) were assessed as parameters for prognostic significance. Multivariate analysis also showed a significant correlation between the American Society of Anesthesiologists score and height loss of the vertebral body and the final outcome. The presence of signal changes on magnetic resonance imaging showed the highest odds ratio adjusted. CONCLUSIONS: Appropriate patient selection is essential for achieving clinical success. Better results can be expected in patients with an American Society of Anesthesiologists score of I and when the level managed is confirmed by magnetic resonance imaging and the vertebral body height loss is less than 70%.