A major goal in cancer research is to develop carriers that can deliver drugs effectively and without side effects. Liposomal and particulate carriers with diameters of ∼100 nm have been widely used to improve the distribution and tumour accumulation of cancer drugs, but so far they have only been effective for treating highly permeable tumours. Here, we compare the accumulation and effectiveness of different sizes of long-circulating, drug-loaded polymeric micelles (with diameters of 30, 50, 70 and 100 nm) in both highly and poorly permeable tumours. All the polymer micelles penetrated highly permeable tumours in mice, but only the 30 nm micelles could penetrate poorly permeable pancreatic tumours to achieve an antitumour effect. We also showed that the penetration and efficacy of the larger micelles could be enhanced by using a transforming growth factor-β inhibitor to increase the permeability of the tumours.

The radiation-induced reactions of onium salts in some kinds of solutions and model compound solutions of chemically amplified electron beam (EB) and X-ray resists have been studied by means of picosecond and nanosecond pulse radiolysis. The following reaction mechanisms of the chemically amplified EB and X-ray resists have been elucidated. The radiation-induced reaction mechanisms are complicated due to the presence of several proton donors. The onium salts directly produce small amounts of Brønsted acids by EB and X-ray exposure and most of the Brønsted acids are formed from proton adducts of the base polymer. The onium salts are strong electron scavengers and promote the generation of the proton adducts in the chemically amplified resists.

A strong effect of radiation damping on the interaction of an ultraintense laser pulse with an overdense plasma slab is found and studied via a relativistic particle-in-cell simulation including ionization. Hot electrons generated by the irradiation of a laser pulse with a radiance of I lambda(2)>10(22) W microm(2)/cm(2) and duration of 20 fs can convert more than 35% of the laser energy to radiation. This incoherent x-ray emission lasts for only the pulse duration and can be intense. The radiation efficiency is shown to increase nonlinearly with laser intensity. Similar to cyclotron radiation, the radiation damping may restrain the maximal energy of relativistic electrons in ultraintense-laser-produced plasmas.

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We use a one-shot measurement technique to study effects of laser prepulses on the electron laser wakefield acceleration driven by relativistically intense laser pulses (lambda=790 nm, 11 TW, 37 fs) in dense helium gas jets. A quasimonoenergetic electron bunch with an energy peak approximately 11.5 MeV[DeltaE/E approximately 10% (FWHM)] and with a narrow-cone angle (0.04pi mm mrad) of ejection is detected at a plasma density of 8 x 10(19) cm(-3). A strong correlation between the generation of monoenergetic electrons and optical guiding of the pulse in a thin channel produced by picosecond laser prepulses is observed. This generation mechanism is well corroborated by two-dimensional particle-in-cell simulations.

Spatial and energy distributions of energetic electrons produced by an ultrashort, intense laser pulse with a short focal length optical system (Ti:sapphire, 12 TW, 50 fs, lambda=790 nm, f/3.5) in a He gas jet are measured. They are shown to depend strongly on the contrast ratio and shape of the laser prepulse. The wave breaking of the plasma waves at the front of the shock wave formed by a proper laser prepulse is found to make a narrow-cone (0.1pi mm mrad) electron injection. These electrons are further accelerated by the plasma wake field generated by the laser pulse up to tens of MeV forming a Maxwell-like energy distribution. In the case of nonmonotonic prepulse, hydrodynamic instability at the shock front leads to a broader, spotted spatial distribution. The numerical analysis based on a two-dimensional (2D) hydrodynamic (for the laser prepulse) and 2D particle-in-cell (PIC) simulation justifies the mechanism of electron acceleration. The PIC calculation predicts that electrons with energy from 10 to 40 MeV form a bunch with a pulse duration of about 40 fs.

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One of the restrictions in the potential use of gold markers for medical imaging/tracking of harder tumors is its size. We propose to use gold nanoparticles which, due to its small size, can be administered conveniently via intravenous injection. One of the factors that determine the clinical utility of nanoparticles is the ability to enter cells. In this report, the stability of gold nanoparticles mixed with different media was determined by UV-vis spectroscopy. Gold nanoparticle size was confirmed by TEM. Intracellular uptake using different gold nanoparticle sizes, incubation times and concentrations were analyzed using Atomic Absorption Spectrometry (AAS). Temperature dependence uptake was also measured using AAS. The results showed that pancreas cancer cells uptake 20 nm gold nanoparticles preferentially compared to other gold nanoparticle sizes. Efficient accumulation of gold nanoparticles into pancreas cancer cells can be achieved at longer incubation time and higher concentration. The findings of this study will help in the design and optimization of the gold nanoparticle-based agents for therapeutic and diagnostic applications of X-ray Drug Delivery System.