Mercedes Santos

Elastin-like recombinamer catalyst-free click gels: characterization of poroelastic and intrinsic viscoelastic properties.

Elastin-like recombinamer catalyst-free click gels (ELR-CFCGs) have been prepared and characterized by modifying both a structural ELR (VKVx24) and a biofunctionalized ELR-bearing RGD cell-adhesion sequence (HRGD6) to bear the reactive groups needed to form hydrogels via a click reaction. Prior to formation of the ELR-CFCGs, azide-bearing and cyclooctyne-modified ELRs were also synthesized. Subsequent covalent crosslinking was based on the reaction between these azide and cyclooctyne groups, which takes place under physiological conditions and without the need for a catalyst. The correlation among SEM micrographs, porosity, swelling ratio, and rheological measurements have been carried out. The storage and loss moduli at 1Hz are in the range 1-10kPa and 100-1000Pa, respectively. The linear dependence of |G∗| on f(½) and the peak value of tan δ were considered to be consistent with a poroelastic mechanism dominating the frequency range 0.3-70Hz. The discrete relaxation spectrum was obtained from stress relaxation measurements (t>5s). The good fit of the relaxation modulus to decrease exponential functions suggests that an intrinsic viscoelastic mechanism dominates the transients. Several recombinamer concentrations and temperatures were tested to obtain gels with fully tuneable properties that could find applications in the biomedical field.

Short enantioselective approach to substituted triazolopyridazines from [(S)R]-1-(1E, 3E)-1-p-tolylsulfinyl-1,3-pentadiene

Abstract Enantiomerically pure hydroxy substituted triazolopyridazine 5a was obtained in one pot under mild conditions by reaction of (+)-( R )-(1 E ,3 E )-1-( p -tolylsulfinyl)-1,3-pentadiene and 4-methyl-1,2,4-triazoline-3,5-dione in the presence of P(OMe) 3 . The process involved a tandem Diels-Alder cycloaddition/sulfoxide-sulfenate rearrangement and trapping of the intermediate sulfenate.

Efficient Cell and Cell-Sheet Harvesting Based on Smart Surfaces Coated with a Multifunctional and Self-Organizing Elastin-Like Recombinamer

A wide range of smart surfaces with novel properties relevant for biomedical applications have been developed recently. Herein we focus on thermoresponsive surfaces that switch between cell-adherent and nonadherent states and their applications for cell harvesting. These smart surfaces are obtained by covalently coupling a tailored elastin-like recombinamer onto glass surfaces by means of the well-known and widely applied Click Chemistry methodology. The resulting recombinamer-functionalized surfaces have been characterized by means of water contact angle measurements, XPS and TOF-SIMS. A cell-based analysis of these surfaces with human fibroblasts showed a high degree of adhesion to the surface in its adherent state (37 °C), thus, promoting cell viability and proliferation. A temperature decrease triggers reorganization of the recombinamer, thus, markedly increasing the number of nonadherent domains and masking the adherent ones. This process allows a specific and efficient temporal control of cell adhesion and cell detachment. After determination of the properties required for a suitable cell-harvesting system, optimization of the process allows single cells or cell sheets from at least two types of cells (HFF-1 and ADSCs) to be rapidly harvested.

DIELS-ALDER REACTIONS OF (S)R-(1E,3E)-1-P -TOLYLSULFINYL-1,3-PENTADIENE WITH MONOSUBSTITUTED ETHYLENES

Abstract Diels-Alder reactions of [(S)R]-(1E,3E)-1-p-tolylsulfinyl-1,3-pentadiene with 1-pyrrolidinyl-1-cyclohexene and methyl acrylate evidenced: i) low reactivity of the diene regardless of the electronic character of the dienophile (high pressures were always required); ii) a complete regio- and endo-selectivity (both controlled by the sulfoxide), but a low π-facial diastereoselectivity in the cycloaddition with enamine; iii) diastereoselectivity (facial and endo exo ) for the reaction with methyl acrylate is dependent on the regiochemistry (mainly controlled by the methyl substituent).

Gold Tailored Photosensitive Elastin-like Polymer: Synthesis of Temperature, pH and UV-vis Sensitive Probes.

Here, we describe a procedure to manufacture smart hybrid probes that exhibit tunable optical properties as a function of multiple environmental variations. Initially, we achieved a one-pot synthesis of gold-PREP (photo-responsive elastin-like polymer) conjugate Gold-AzoGlu15 via reduction of auric acid in the presence of PREP AzoGlu15. Outstandingly, Gold-AzoGlu15 exhibited pH and temperature sensitiveness. However, Gold-AzoGlu15 was not UV-vis sensitive. We noticed that photo-isomerisation of azobenzene moieties in Gold-AzoGlu15 could not be detected by UV-vis spectroscopy. In a subsequent step, we explored the use of cyclodextrins and the formation of alkanethiol mixed-monolayers over mother Gold-AzoGlu15 by thiol-place exchange reactions in order to decouple photo-isomerisation of azobenzene from the bulk phase absorption. In this sense we achieved the synthesis of β-cyclodextrin capped Gold-CD-AzoGlu15. Notable was that cis-trans photo-conversion of azobenzene groups in Gold-CD-AzoGlu15 could be successfully detected. Finally, we present the optical properties exhibited by multi-sensitive probe Gold-CD-AzoGlu15 as a function of pH, temperature and UV-vis irradiation. We think that gold-PREP hybrids could be of great interest in the design of multi-functional chromophore-metal nanocomposites that operate in aqueous media for the development of multi-stimuli sensitive detectors for biosensing applications.

Synthesis and photooxygenation of 2-thiofuran derivatives: a mild and direct access to O,S-dimethyl and O-methyl-S-phenyl thiomaleates

New 3-bromo-2-thio and 3-bromo-2,5-bis-(thio) furan derivatives have been synthesized and their synthetic potential has been assessed by their conversion into O,S-dimethyl and O-methyl-S-phenyl thiomaleates via methylene blue sensitized photooxygenation.

Recent Contributions of Elastin-Like Recombinamers to Biomedicine and Nanotechnology

The emergence of the new scientific field known as nanomedicine is being catalyzed by multiple improvements in nanoscience techniques and significant progress in materials science, especially as regards the testing of novel and sophisticated biomaterials. This conjuncture has furthered the development of promising instruments in terms of detection, bioanalysis, therapy, diagnostics and imaging. Some of the most innovative new biomaterials are protein-inspired biomimetic materials in which modern biotechnology and genetic-engineering techniques complement the huge amount of information afforded by natural protein evolution to create advanced and tailor-made multifunctional molecules. Amongst these protein-based biomaterials, Elastin-like Recombinamers (ELRs) have demonstrated their enormous potential in the fields of biomedicine and nanoscience in the last few years. This broad applicability derives from their unmatched properties, particularly their recombinant and tailor-made nature, the intrinsic characteristics derived from their elastin-based origin (mainly their mechanical properties and ability to self-assemble as a result of their stimuli-responsive behavior), their proven biocompatibility and biodegradability, as well as their versatility as regards incorporating advanced chemical or recombinant modifications into the original structure that open up an almost unlimited number of multifunctional possibilities in this developing field. This article provides an updated review of the recent challenges overcome by using these recombinant biomaterials in the fields of nano- and biomedicine, ranging from nanoscale applications in surface modifications and self-assembled nanostructures to drug delivery and regenerative medicine.

Synthesis and photooxygenation of (S)-p-tolylsulfinylfuran derivatives

Abstract The synthesis of different (S)-1,4-dicarbonyl-2-(p-tolylsulfinyl)-2-alkenes by photooxygenation of enantiomerically pure (S)-p-tolylsulfinylfurans is reported.

Biocompatible ELR-Based Polyplexes Coated with MUC1 Specific Aptamers and Targeted for Breast Cancer Gene Therapy

The search for new and biocompatible materials with high potential for improvement is a challenge in gene delivery applications. A cell type specific vector made of elastin-like recombinamer (ELR) and aptamers has been specifically designed for the intracellular delivery of therapeutic material for breast cancer therapy. A lysine-enriched ELR was constructed and complexed with plasmid DNA to give positively charged and stable polyplexes. Physical characterization of these polyplexes showed a particle size of around 140 nm and a zeta potential of approximately +40 mV. The incorporation of MUC1-specific aptamers into the polyplexes resulted in a slight decrease in zeta potential but increased cell transfection specificity for MCF-7 breast cancer cells with respect to a MUC1-negative tumor line. After showing the transfection ability of this aptamer-ELR vector which is facilitated mainly by macropinocytosis uptake, we demonstrated its application for suicide gene therapy using a plasmid containing the gene of the toxin PAP-S. The strategy developed in this work about using ELR as polymeric vector and aptamers as supplier of specificity to deliver therapeutic material into MUC1-positive breast cancer cells shows promising potential and continues paving the way for ELRs in the biomedical field.

Recombinant DNA technology and click chemistry: a powerful combination for generating a hybrid elastin-like-statherin hydrogel to control calcium phosphate mineralization

Understanding the mechanisms responsible for generating different phases and morphologies of calcium phosphate by elastin-like recombinamers is supreme for bioengineering of advanced multifunctional materials. The generation of such multifunctional hybrid materials depends on the properties of their counterparts and the way in which they are assembled. The success of this assembly depends on the different approaches used, such as recombinant DNA technology and click chemistry. In the present work, an elastin-like recombinamer bearing lysine amino acids distributed along the recombinamer chain has been cross-linked via Huisgen [2 + 3] cycloaddition. The recombinamer contains the SNA15 peptide domains inspired by salivary statherin, a peptide epitope known to specifically bind to and nucleate calcium phosphate. The benefit of using click chemistry is that the hybrid elastin-like-statherin recombinamers cross-link without losing their fibrillar structure. Mineralization of the resulting hybrid elastin-like-statherin recombinamer hydrogels with calcium phosphate is described. Thus, two different hydroxyapatite morphologies (cauliflower- and plate-like) have been formed. Overall, this study shows that crosslinking elastin-like recombinamers leads to interesting matrix materials for the generation of calcium phosphate composites with potential applications as biomaterials.