Solid-Phase Synthesis of Gly-Ψ[CH(CF3)NH]-Peptides

Turing-Structured Covalent Organic Framework Membranes for Fast and Precise Peptide Separations

Turing structures have emerged as promising features for separation membranes, enabling significantly enhanced water permeation due to their ultra-permeable internal cavities. So far, Turing structures are constrained by the highly cross-linked and heterogeneous porosities, impeding them from the application of molecular separations requiring loose but regular pore structures. This work reports a covalent organic frameworks (COFs) membrane with nanoscale striped Turing structures for fast and precise molecular separations. Porous and hydrophilic modulation layers based on metal-polyphenol chemistry are constructed on polymeric substrates, which are capable of enhancing the uptake and controlled release of the activator of amines during synthesis. The appropriately reduced diffusion rate triggers the phenomenon of "local activation and lateral inhibition" arising from thermodynamic instability, creating Turing structures with externally striped and internally cavitated architectures. The Turing-type COF membranes exhibit a water permeance of 45.0 L m-2 h-1 bar-1, which is approximately 13 times greater than the non-Turing membranes, and an ultrahigh selectivity of up to 638 for two model peptides. This work demonstrates the feasibility that Turing structures with ultra-permeable internal cavities can be created in COF membranes and underscores their superiority in molecular separations, including but not limited to high-value pharmaceuticals.

Fluorinated PAMAM-Arginine Carrier Prodrugs for pH-Sensitive Sustained Ibuprofen Delivery

OBJECTIVE

The development of an efficient, multifunctional drug delivery system overcoming different obstacles generally associated with drug formulations, including the poor accumulation of the active principle in the target site and its sustained release for prolonged time.

METHODS

Our study proposes the development of a fluorinated poly(amidoamine) (PAMAM) carrier prodrug combining drug release boosted in alkaline environments with a possible implementation in 19F MRI applications. In particular, we functionalized the terminal primary amines of PAMAM G2 and G4 through an ad hoc designed fluorinated ibuprofen-arginine Michael acceptor to obtain multifunctional ibuprofen-PAMAM-Arg conjugates.

RESULTS

These carriers demonstrated pH-dependent and sustained ibuprofen release for more than 5 days. This advantage was observed in both weak alkaline and physiological buffer solutions, allowing to overcome the limits associated to the burst release from similar fluorinated Arg-PAMAM dendrimers with ibuprofen physically encapsulated.

CONCLUSION

These findings, coupled to the high biocompatibility of the system, suggest a potential synergistic biomedical application of our conjugates, serving as vehicles for drug delivery and as 19F magnetic resonance imaging contrast agents.