José R. Couceiro

Soft contact lenses functionalized with pendant cyclodextrins for controlled drug delivery.

The aim of this work was to develop acrylic hydrogels with high proportions of cyclodextrins maintaining the mechanical properties and the biocompatibility of the starting hydrogels, but notably improving their ability to load drugs and to control their release rate. Poly(hydroxyethylmethacrylate) hydrogels were prepared by copolymerization with glycidyl methacrylate (GMA) at various proportions and then beta-cyclodextrin (betaCD) was grafted to the network by reaction with the glycidyl groups under mild conditions. This led to networks in which the betaCDs form no part of the structural chains but they are hanging on 2-3 ether bonds through the hydroxyl groups. The pendant betaCDs did not modify the light transmittance, glass transition temperature, swelling degree, viscoelasticity, oxygen permeability, or surface contact angle of the hydrogels, but decreased their friction coefficient by 50% and improved diclofenac loading by 1300% and enhanced drug affinity 15-fold. The hydrogels were able to prevent drug leakage to a common conservation liquid for soft contact lenses (SCLs) and to sustain drug delivery in lacrimal fluid for two weeks. To summarize, the hydrogels with pendant betaCDs are particularly useful for the development of cytocompatible medicated implants or biomedical devices, such as drug-loaded SCLs.

Transition metal catalysis in the mitochondria of living cells

The development of transition metal catalysts capable of promoting non-natural transformations within living cells can open significant new avenues in chemical and cell biology. Unfortunately, the complexity of the cell makes it extremely difficult to translate standard organometallic chemistry to living environments. Therefore, progress in this field has been very slow, and many challenges, including the possibility of localizing active metal catalysts into specific subcellular sites or organelles, remain to be addressed. Herein, we report a designed ruthenium complex that accumulates preferentially inside the mitochondria of mammalian cells, while keeping its ability to react with exogenous substrates in a bioorthogonal way. Importantly, we show that the subcellular catalytic activity can be used for the confined release of fluorophores, and even allows selective functional alterations in the mitochondria by the localized transformation of inert precursors into uncouplers of the membrane potential.

Effects of lyophilization on human amniotic membrane

Purpose:  This study aimed to evaluate the effects of lyophilization and cryopreservation on human amniotic membrane (HAM) in terms of histological characteristics and growth factor levels.

Donor age and gestational age influence on growth factor levels in human amniotic membrane.

Acta Ophthalmol. 2010: 88: e211–e216

Effects of alprazolam on T-cell immunosuppressive response to surgical stress in mice

Mice submitted to surgical stress induced by laparotomy and treated with chronic alprazolam (1 mg/kg) showed a reduction in stress-induced suppression of thymus and spleen cellularity, as well as in peripheral T lymphocyte population. The blastic response of spleen lymphoid cells was also assessed and found to partially supress the inhibitory effect of surgery.

Ruthenium-Catalyzed Azide–Thioalkyne Cycloadditions in Aqueous Media: A Mild, Orthogonal, and Biocompatible Chemical Ligation

Abstract The development of efficient metal‐promoted bioorthogonal ligations remains as a major scientific challenge. Demonstrated herein is that azides undergo efficient and regioselective room‐temperature annulations with thioalkynes in aqueous milieu when treated with catalytic amounts of a suitable ruthenium complex. The reaction is compatible with different biomolecules, and can be carried out in complex aqueous mixtures such as phosphate buffered saline, cell lysates, fetal bovine serum, and even living bacteria (E. coli). Importantly, the reaction is mutually compatible with the classical CuAAC.

Anion Recognition as a Supramolecular Switch of Cell Internalization

The cell internalization of designed oligoarginine peptides equipped with six glutamic acid residues and an anionic pyranine at the N-terminus is triggered upon addition of a supramolecular host. This host binds specifically to the pyranine moiety, enabling the complex to traverse the cell membrane. Interestingly, none of the components, neither the host nor the guest, are able to cross the cell membrane on their own.

Ruthenation of Non-stacked Guanines in DNA G-Quadruplex Structures: Enhancement of c-MYC Expression.

Abstract Guanine quadruplexes (GQs) are compact four‐stranded DNA structures that play a key role in the control of a variety of biological processes, including gene transcription. Bulky ruthenium complexes featuring a bipyridine, a terpyridine, and one exchangeable ligand ([Ru(terpy)(bpy)X]n+) are able to metalate exposed guanines present in the GQ of the c‐MYC promoter region that are not involved in quadruplex base pairing. qRT‐PCR and western‐blot experiments indicated that the complexes promote a remarkable increase in the expression of this oncogene. We also show that exchangeable thioether ligands (X=RSR′, Met) allow regulation of the metalating activity of the complex with visible light.

Autoradiographic evidence of opioid binding sites in rat growth plate chondrocytes.

After 125I-beta-endorphin was intravenously injected in rats, an autoradiographic study of distal femur growth plates was performed. Results show a specific binding of the radiolabelled peptide to chondrocytes suggesting the possible existence of an opiate modulation of growth plate physiology.

Intracellular Deprotection Reactions Mediated by Palladium Complexes Equipped with Designed Phosphine Ligands

Discrete palladium(II) complexes featuring purposely designed phosphine ligands can promote depropargylation and deallylation reactions in cell lysates. These complexes perform better than other palladium sources, which apparently are rapidly deactivated in such hostile complex media. This good balance between reactivity and stability allows the use of these discrete phosphine palladium complexes in living mammalian cells, whereby they can mediate similar transformations. The presence of a phosphine ligand in the coordination sphere of palladium also provides for the introduction of targeting groups, such as hydrophobic phosphonium moieties, which facilitate the accumulation of the complexes in mitochondria.