Silica-Coated Micrometer-Sized Latex Particles

A series of silica-coated micrometer-sized poly(methyl methacrylate) latex particles are prepared using a Stöber silica deposition protocol that employs tetraethyl orthosilicate (TEOS) as a soluble silica precursor. Given the relatively low specific surface area of the latex particles, silica deposition is best conducted at relatively high solids to ensure a sufficiently high surface area. Such conditions aid process intensification. Importantly, physical adsorption of chitosan onto the latex particles prior to silica deposition minimizes secondary nucleation and promotes the formation of silica shells: in the absence of chitosan, well-defined silica overlayers cannot be obtained. Thermogravimetry studies indicate that silica formation is complete within a few hours at 20 °C regardless of the presence or absence of chitosan. Kinetic data obtained using this technique suggest that the adsorbed chitosan chains promote surface deposition of silica onto the latex particles but do not catalyze its formation. Systematic variation of the TEOS/latex mass ratio enables the mean silica shell thickness to be tuned from 45 to 144 nm. Scanning electron microscopy (SEM) studies of silica-coated latex particles after calcination at 400 °C confirm the presence of hollow silica particles, which indicates the formation of relatively smooth (albeit brittle) silica shells under optimized conditions. Aqueous electrophoresis and X-ray photoelectron spectroscopy studies are also consistent with latex particles coated in a uniform silica overlayer. The silica deposition formulation reported herein is expected to be a useful generic strategy for the efficient coating of micrometer-sized particles at relatively high solids

Timing resolution for an optical fibre-based detector in a 74 MeV proton therapy beam

A Terbium activated Gadolinium Oxysulfide (Gd2O2S:Tb)-filled optical fibre sensor was developed and tested as a proton therapy beam dosimeter on a 74 MeV proton beam. Tests were carried out at the TRIUMF proton therapy centre, where a passively scattered beam is used for treatment. To create a clinically relevant spread-out Bragg peak, a modulator wheel with steps of varying thickness is employed. To determine the sensor’s response in a 23 mm spread out Bragg peak, the sensor signal was sampled at depth intervals of 0.79 mm along the beam axis in a water phantom. The resulting data showed a periodic variation in the signal corresponding to the rotation of the modulator wheel and related to the depth in water of the detector. This timing resolution in the sensor response could find application in quality assurance for modulated proton beam

Additional file 1: Figure S1. of Vimentin and Ki67 expression in circulating tumour cells derived from castrate-resistant prostate cancer

Validation of vimentin and Ki67 staining using the CellSearch platform. Figure S2. Prognostic impact of total CTC in two cohorts of patients with CRPC. Figure S3. Prognostic impact of vimentin/Ki67 CTC proportions and their presence in the unfavourable subgroup. Important validation work performed to justify subsequent experiments and conclusions. Figure S1. details the optimisation on CellSearch of Vimentin and Ki67 antibodies. Figure S2. shows that prognostic analysis of total CTC (regardless of vimentin and Ki67 measurements) is consistent with previous reports. Figure S3. shows that there is no prognostic significance of KI67 or vimentin CTC in the unfavourable prognosis subgroup, and that proportion of Ki67- or vimentin-CTC is less prognostically important than their presence or absence. (PDF 1030 kb