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Purpose: pH enhanced (pHenh) CEST imaging combines the pH sensitivity from amide and guanidino signals, but the saturation parameters have not been optimized. We propose pHdual as a variant of pHenh that suppresses background signal variations, while enhancing pH sensitivity and potential for imaging ischemic brain injury of stroke. Methods: Simulation and in vivo rodent stroke experiments of pHenh MRI were performed with varied RF saturation powers for both amide and guanidino protons to optimize the contrast between lesion/normal tissues, while simultaneously minimizing signal variations across different types of normal tissues. In acute stroke, contrast and volume ratio measured by pHdual imaging were compared with an amide‐CEST approach, and perfusion and diffusion MRI. Results: Simulation experiments indicated that amide and guanidino CEST signals exhibit unique sensitivities across different pH ranges, with pHenh producing greater sensitivity over a broader pH regime. The pHenh data of rodent stroke brain demonstrated that the lesion/normal tissue contrast was maximized for an RF saturation power pair of 0.5 μT at 2.0 ppm and 1.0 μT at 3.6 ppm, whereas an optimal contrast‐to‐variation ratio (CVR) was obtained with a 0.7 μT saturation at 2.0 ppm and 0.8 μT at 3.6 ppm. In acute stroke, CVR optimized pHenh (i.e., pHdual) achieved a higher sensitivity than the three‐point amide‐CEST approach, and distinct patterns of lesion tissue compared to diffusion and perfusion MRI. Conclusion: pHdual MRI improves the sensitivity of pH‐weighted imaging and will be a valuable tool for assessing tissue viability in stroke. [ABSTRACT FROM AUTHOR]

Uranium extraction from seawater provides the new idea for the development of uranium resources. However, the concentration of uranium in seawater is extremely low (∼3.3 μg/L). Meanwhile, there are a large number of competing ions and microorganisms in the seawater. It is a huge challenge to extract uranium from seawater. In this paper, a double network hydrogels material with effective antifouling ability was prepared for highly efficient uranium sorption. First, poly(hexamethylene biguanide) hydrochloride (PHMB) modified graphene oxide(GO) was prepared (PHMB-GO), and then PHMB-GO was doped into the double network hydrogels structure formed by acrylamide and gelatin in order to obtain (GO-PHMB) 0.4 @Gelatin-PAM, which showed the maximum uranium adsorption capacity reached 625.00 mg∙g−1. More importantly, it exhibited excellent selectivity towards uranium(VI) in the presence of multiple coexisting metal ions in simulated seawater. The K d value for uranium is 1.73 × 104 mL∙g−1, which is far more than other metal ions. The antibacterial and antialgae experiments prove that the adsorption material has a good inhibitory effect on Escherichia coli (E. coli), vibrio vulnificus (V vulnificus) and Staphylococcus aureus (S. aureus). Therefore, (GO-PHMB) 0.4 @Gelatin-PAM is an outstanding candidate for efficient uranium extraction from seawater. [Display omitted] • Antifouling double network hydrogels doped with polyguanidine-modified GO into Gelatin-PAM were successfully prepared. • The maximum theoretical adsorption capacity of (GO-PHMB) 0.4 @Gelatin-PAM DN hydrogels for uranium was 625.00 mg∙g−1. • The (GO-PHMB) 0.4 @Gelatin-PAM DN hydrogels material had excellent antibacterial and anti-algal properties. [ABSTRACT FROM AUTHOR]

Derivatives of peptides of the TIPP (Tyr-Tic-Phe-Phe; Tic=1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid) family containing a guanidino (Guan) function in place of the N-terminal amino group were synthesized in an effort to improve their blood-brain barrier permeability. Unexpectedly, N-terminal amidination significantly altered the in vitro opioid activity profiles. Guan-analogues of TIPP-related δ opioid antagonists showed δ partial agonist or mixed δ partial agonist/μ partial agonist activity. Guanidinylation of the mixed μ agonist/δ antagonists H-Dmt-Tic-Phe-Phe-NH2 (DIPP-NH2) and H-Dmt-TicΨ[CH2NH]Phe-Phe-NH2 (DIPP-NH2[Ψ]) converted them to mixed μ agonist/δ agonists. A docking study revealed distinct positioning of DIPP-NH2 and Guan-DIPP-NH2 in the δ receptor binding site. Lys(3)-analogues of DIPP-NH2 and DIPP-NH2[Ψ] (guanidinylated or non-guanidinylated) turned out to be mixed μ/κ agonists with δ antagonist-, δ partial agonist- or δ full agonist activity. Compounds with some of the observed mixed opioid activity profiles have therapeutic potential as analgesics with reduced side effects or for treatment of cocaine addiction., (Copyright © 2013 Elsevier Ltd. All rights reserved.)