Polymeric Nanoreactors with Chemically Tunable Redox Responsivity.

Bioresponsive nanomaterials are increasingly important in a variety of applications such as disease imaging, drug delivery, and tissue engineering. However, it remains a big challenge to manipulate response efficacy of such materials for performance optimization in a highly complex milieu in vivo. Here, we developed chemically adjustable nanoreactors (CANs) with the structure of polymeric cores and albumin shells to achieve tunable redox responsivity. In vitro characterization demonstrates stable, spherical nanoparticles of the CANs with a particle size of about 50 nm. The fluorescence activation ratios of the CANs are determined by various albumin modification densities on the shell. Meanwhile, the response sensitivity of the CANs to GSH levels (0.6-4 mM) can be tuned by acid-base properties of polymeric blocks in the core. This unique tunable redox responsivity enables the CANs suitable for probe optimization in cancer imaging both in vivo and at histological levels. Overall, this study offers a new design strategy for manipulation on performance of core/shell nanoreactors or bioresponsive nanomaterials.

[Impact of magnetic attachment keepers on magnetic resonance imaging examination].

OBJECTIVE: To evaluate the effects of magnetic attachment keepers on MRI images. METHODS: In in vitro part, keepers of MAGFIT EX 400, MAGFIT EX 600 and MAGNEDISC 800 magnetic attachment systems were cast into standard root-caps with different alloy respectively, including nickel-chromium alloy and gold-palladium alloy, or not be cast for contrast. In in vivo part, volunteers with keepers in different position and amount were included. All the specimens and volunteers were imaged by a Siemens SONATA 1.5-T MRI scanner. Extent of the artifacts in every slice was measured. The magnitude of the artifacts and the distortion of the anatomic structures were compared. RESULTS: All kinds of keepers being studied produced obvious MRI artifacts. The extent of MRI artifacts induced by MAGFIT EX 400 keepers, MAGFIT EX 600 keepers and MAGNEDISC 800 keepers are 158.94 mm, 168.52 mm and 173.00 mm, respectively. The images of mental region, tongue, palate, jawbone and sinus were evidently obscured by artifacts in all cases. When keeper was put in the molar region, the keeper-related MRI artifact may obscure the imaging of brain, spinal cord. SE sequence with right-left frequency-encoding direction was more desirable in MRI for the patients with magnetic attachment keepers. CONCLUSION: Keepers of magnetic attachment system did induce obvious artifacts in MRI examination.