Neuro-vascular central nervous recording/stimulating system: Using nanotechnology probes

Electrical recording from spinal cord vascular capillary bed has been achieved demonstrating that the intravascular space may be utilized as a means to address brain activity with out violating the brain parenchyma. While the initial demonstration was implemented using electrically insulated platinum electrodes in vitro, the possibility of using conducting polymer filaments is now being explored. This paper presents a set of highly possible future scenarios where the integration of electrophysiology and novel polymer technology may serve as a new approach towards basic and medical neuroscience.This revised version was published online in August 2005 with a corrected issue number.     

Block Copolymer Micellization as a Protection Strategy for DNA Origami

DNA nanotechnology enables the synthesis of nanometer‐sized objects that can be site‐specifically functionalized with a large variety of materials. For these reasons, DNA‐based devices such as DNA origami are being considered for applications in molecular biology and nanomedicine. However, many DNA structures need a higher ionic strength than that of common cell culture buffers or bodily fluids to maintain their integrity and can be degraded quickly by nucleases. To overcome these deficiencies, we coated several different DNA origami structures with a cationic poly(ethylene glycol)–polylysine block copolymer, which electrostatically covered the DNA nanostructures to form DNA origami polyplex micelles (DOPMs). This straightforward, cost‐effective, and robust route to protect DNA‐based structures could therefore enable applications in biology and nanomedicine where unprotected DNA origami would be degraded.     

Enantiomeric PLA–PEG block copolymers and their stereocomplex micelles used as rifampin delivery

A novelty approach to self-assembling stereocomplex micelles by enantiomeric PLA–PEG block copolymers as a drug delivery carrier was described. The particles were encapsulated by enantiomeric PLA–PEG stereocomplex to form nanoscale micelles different from the microspheres or the single micelles by PLLA or PDLA in the reported literatures. First, the block copolymers of enantiomeric poly(l-lactide)–poly(ethylene–glycol) (PLLA–PEG) and poly(D-lactide)–poly(ethylene–glycol) (PDLA–PEG) were synthesized by the ring-opening polymerization of l-lactide and d-lactide in the presence of monomethoxy PEG, respectively. Second, the stereocomplex block copolymer micelles were obtained by the self-assembly of the equimolar mixtures of enantiomeric PLA–PEG copolymers in water. These micelles possessed partially the crystallized hydrophobic cores with the critical micelle concentrations (cmc) in the range of 0.8–4.8 mg/l and the mean hydrodynamic diameters ranging from 40 to 120 nm. The micelle sizes and cmc values obviously depended on the hydrophobic block PLA content in the copolymer. Compared with the single PLLA–PEG or PDLA–PEG micelles, the cmc values of the stereocomplex micelles became lower and the sizes of the stereocomplex micelles formed smaller. And lastly, the stereocomplex micelles encapsulated with rifampin were tested for the controlled release application. The rifampin loading capacity and encapsulation efficiency by the stereocomplex micelles were higher than those by the single polymer micelles, respectively. The drug release time in vitro was depending on the composites of the block copolymers and also could be controlled by the polymer molecular weight and the morphology of the polymer micelles.