Mechanically tough dynamic poly(disulfide)s crosslinked by acylsemicarbazides.

Acylsemicarbazide is used to toughen a dynamic poly(disulfide) network by forming synergistic covalent and noncovalent crosslinkers. The resulting dry supramolecular network exhibits enhanced stretchability, mechanical strength and toughness while retaining dynamic reconfigurability.

Reinforcement Learning for Synchronization of Heterogeneous Multiagent Systems by Improved Q-Functions.

This article dedicates to investigating a methodology for enhancing adaptability to environmental changes of reinforcement learning (RL) techniques with data efficiency, by which a joint control protocol is learned using only data for multiagent systems (MASs). Thus, all followers are able to synchronize themselves with the leader and minimize their individual performance. To this end, an optimal synchronization problem of heterogeneous MASs is first formulated, and then an arbitration RL mechanism is developed for well addressing key challenges faced by the current RL techniques, that is, insufficient data and environmental changes.

A Second Generation Mn-Porphyrin Dimer with a Twisted Linker as a Potential Blood Pool Agent for MRI: Tuning the Geometry and Binding with HSA.

Blood-pool agents (BPAs) are MRI contrast agents (CAs) characterized by their long circulation in the vascular system to provide an extended time window for high-resolution MR angiography (MRA). Prolonged vascular retention, however, impedes the excretion of BPAs. Therefore, chemical strategy to regulate the balance between retention and clearance is important to reach optimal pharmacokinetics.

Manganese-porphyrin-enhanced MRI for the detection of cancer cells: A quantitative in vitro investigation with multiple clinical subtypes of breast cancer.

Magnetic resonance imaging (MRI) contrast agents (CAs) are chemical compounds that can enhance image contrast on T1- or T2- weighted MR image. We have previously demonstrated the potential of MnCl2, a manganese-based CA, in cellular imaging of breast cancer using T1-weighted MRI. In this work, we examined the potential of another class of manganese-based CAs, manganese porphyrins (MnPs), for sensitive cellular detection of multiple clinical subtypes of breast cancer using quantitative MRI.

Ultrashort echo time magnetic resonance imaging of the lung using a high-relaxivity t1 blood-pool contrast agent.

The lung remains one of the most challenging organs to image using magnetic resonance imaging (MRI) due to intrinsic rapid signal decay. However, unlike conventional modalities such as computed tomography, MRI does not involve radiation and can provide functional and morphologic information on a regional basis. Here we demonstrate proof of concept for a new MRI approach to achieve substantial gains in a signal to noise ratio (SNR) in the lung parenchyma: contrast-enhanced ultrashort echo time (UTE) imaging following intravenous injection of a high-relaxivity blood-pool manganese porphyrin T1 contrast agent.

Binding of a dimeric manganese porphyrin to serum albumin: towards a gadolinium-free blood-pool T1 MRI contrast agent.

As the first clinically approved gadolinium-based blood-pool MRI contrast agent, gadofosveset was designed to bind to human serum albumin (HSA) reversibly, extending the circulation time in the bloodstream. This valuable pharmacokinetic property required for vasculature imaging, however, raises the risk of release and accumulation of gadolinium in vivo. The binding of gadofosveset to HSA significantly increases the relaxivity at low field, which decreases drastically when the magnetic field increases, limiting the applications of gadofosveset at fields of 3 T and higher.

Complementary strategies for developing Gd-free high-field T₁ MRI contrast agents based on Mn(III) porphyrins.

Mn(III) porphyrin (MnP) holds the promise of addressing the emerging challenges associated with Gd-based clinical MRI contrast agents (CAs), namely, Gd-related adverse effect and decreasing sensitivity at high clinical magnetic fields. Two complementary strategies for developing new MnPs as Gd-free CAs with optimized biocompatibility were established to improve relaxivity or clearance rate. MnPs with distinct and tunable pharmacokinetic properties can consequently be constructed for different in vivo applications at clinical field of 3 T.

Gadolinium-free T1 contrast agents for MRI: tunable pharmacokinetics of a new class of manganese porphyrins.

Purpose: To evaluate a new class of manganese porphyrins with tunable pharmacokinetics as potential gadolinium (Gd)-free T1 agents for contrast-enhanced magnetic resonance imaging (MRI).

Materials And Methods: Two new contrast agents, MnTCP and MnP2, were evaluated in four female rats. MRI was performed daily up to 3 days postinjection (0.