Carolina de las Heras Alarcón

Stimuli responsive polymers for biomedical applications

Polymers that can respond to external stimuli are of great interest in medicine, especially as controlled drug release vehicles. In this critical review, we consider the types of stimulus response used in therapeutic applications and the main classes of responsive materials developed to date. Particular emphasis is placed on the wide-ranging possibilities for the biomedical use of these polymers, ranging from drug delivery systems and cell adhesion mediators to controllers of enzyme function and gene expression (134 references).

Bioadhesion at micro-patterned stimuli-responsive polymer brushes

The synthesis of poly(N-isopropylacrylamide) brushes within micropatterned domains at surfaces and the performance of these functionalised surfaces in short-term bioadhesion assays under varying conditions are described. The polymer brushes show temperature dependent behaviour at surfaces as demonstrated by changes in contact angle, surface energy components and aqueous phase AFM. The responses in the polymer brush domains result in spatially defined, and temperature mediated, attachment of a model protein, BSA, and the common oral bacteria Streptococcus mutans.

Synthetic polymers as drugs and therapeutics

Synthetic polymers are of increasing interest as therapeutic agents owing to their enhanced pharmacokinetic profiles relative to small molecule drugs. Multifunctional polymers are now being prepared that can ‘hide’ biologically active compounds, such as cytotoxic agents, therapeutic proteins or nucleic acids, until they reach target sites in the body, but which can then release the agent in situ to effect the therapy. In this feature article we consider the sophisticated macromolecular constructs that are being developed, ranging from polymer–drug conjugates to self-assembled polymer–biopolymer complexes. These polymer therapeutics are likely to form the ‘next generation’ of medicines, with improved efficacy against a wide spectrum of diseases.

Cross-Linked Network Development in Compatibilized Alkyd/Acrylic Hybrid Latex Films for the Creation of Hard Coatings

Hybrids made from an alkyd resin and an acrylic copolymer can potentially combine the desired properties of each component. Alkyd/acrylic hybrid latex particles were synthesized via miniemulsion polymerization and used to create films at room temperature. Comparisons of the alkyd auto-oxidative cross-linking rates and the associated network development are made between two alkyd resins (with differing levels of hydrophilicity as measured by their acid numbers). The effects of increasing the compatibilization between the alkyd and the acrylic phase via functionalization with glycidyl methacrylate (GMA) are investigated. Magnetic resonance profiling and microindentation measurements reveal that film hardening occurs much faster in a GMA-functionalized alkyd hybrid than in the standard hybrid. The films hardness increases by a factor of 4 over a 5-day period. The rate of cross-linking is significantly slower in nonfunctionalized alkyd hybrid films and when the more hydrophilic alkyd resin is used. Tensile deformation of the hybrid latex films reveals the effects of GMA functionalization and drier concentration in creating a denser cross-linked network. Modeling of the tensile deformation behavior of the hybrid films used a combination of the upper convected Maxwell model (to describe the viscoelastic component) and the Gent model (to describe the elastic component). The modeling provides a correlation between the cross-linked network formation and the resulting mechanical properties.