Advances in Stimuli-responsive Hydrogels for Tissue Engineering and Regenerative Medicine Applications: A Review Towards Improving Structural Design for 3D Printing

The physicochemical properties of polymeric hydrogels render them attractive for the development of 3D printed prototypes for tissue engineering in regenerative medicine. Significant effort has been made to design hydrogels with desirable attributes that facilitate 3D printability. In addition, there is significant interest in exploring stimuli-responsive hydrogels to support automated 3D printing into more structurally organised prototypes such as customizable bio-scaffolds for regenerative medicine applications. Synthesizing stimuli-responsive hydrogels is dependent on the type of design and modulation of various polymeric materials to open novel opportunities for applications in biomedicine and bio-engineering. In this review, the salient advances made in the design of stimuli-responsive polymeric hydrogels for 3D printing in tissue engineering are discussed with a specific focus on the different methods of manipulation to develop 3D printed stimuli-responsive polymeric hydrogels. Polymeric functionalisation, nano-enabling and crosslinking are amongst the most common manipulative attributes that affect the assembly and structure of 3D printed bio-scaffolds and their stimuli- responsiveness. The review also provides a concise incursion into the various applications of stimuli to enhance the automated production of structurally organized 3D printed medical prototypes.

Molecularly Imprinted Polymers as State-of-the-Art Drug Carriers in Hydrogel Transdermal Drug Delivery Applications

Molecularly Imprinted Polymers (MIPs) are polymeric networks capable of recognizing determined analytes. Among other methods, non-covalent imprinting has become the most popular synthesis strategy for Molecular Imprinting Technology (MIT). While MIPs are widely used in various scientific fields, one of their most challenging applications lies within pharmaceutical chemistry, namely in therapeutics or various medical therapies. Many studies focus on using hydrogel MIPs in transdermal drug delivery, as the most valuable feature of hydrogels in their application in drug delivery systems that allow controlled diffusion and amplification of the microscopic events. Hydrogels have many advantages over other imprinting materials, such as milder synthesis conditions at lower temperatures or the increase in the availability of biological templates like DNA, protein, and nucleic acid. Moreover, one of the most desirable controlled drug delivery applications is the development of stimuli-responsive hydrogels that can modulate the release in response to changes in pH, temperature, ionic strength, or others. The most important feature of these systems is that they can be designed to operate within a particular human body area due to the possibility of adapting to well-known environmental conditions. Therefore, molecularly imprinted hydrogels play an important role in the development of modern drug delivery systems.

Femto- to Millisecond Time-Resolved Photodynamics of a Double-Functionalized Push-Pull Organic Linker: Potential Candidate for Optoelectronically Active MOFs

The design of improved organic linkers for the further engineering of smarter metal–organic framework (MOF) materials has become a paramount task for a wide number of material scientists. In this report, a luminescent double-functionalized push–pull (electron donor–acceptor) archetype organic molecule, dimethyl 4-amino-8-cyanonaphthalene-2,6-dicarboxylate (Me₂CANADC), has been synthesized and characterized. The optical steady-state properties of Me₂CANADC are strongly influenced by the surrounding environment as a direct consequence of its strong charge transfer (CT) character. The relaxation from its first electronically excited singlet state follows a double pathway: (1) on one side deactivating from its local excited (LE) state in the sub-picosecond or picosecond time domain, and (2) on the other side undergoing an ultrafast intramolecular charge transfer (ICT) reaction that is slowing down in viscous solvents. The deactivation to the ground state of these species with CT character is the origin of the Me₂CANADC luminescence, and they present solvent-dependent lifetime values ranging from 8 to 18 ns. The slow photodynamics of Me₂CANADC unveils the coexistence of a non-emissive triplet excited state and the formation of a long-lived charge separated state (2 µs). These observations highlight the promising optical properties of Me₂CANADC linker, opening a window for the design of new functional MOFs with huge potential to be applied in the fields of luminescent sensing and optoelectronics.

One-pot synthesis of magnetic molecularly imprinted microspheres by RAFT precipitation polymerization for the fast and selective removal of 17β-estradiol

A one-pot synthesis strategy was developed to prepare magnetic molecularly imprinted microspheres for the selective recognition and fast removal of 17-beta-estradiol.

Molecular imprinted polymers as drug delivery vehicles

This review is aimed to discuss the molecular imprinted polymer (MIP)-based drug delivery systems (DDS). Molecular imprinted polymers have proved to possess the potential and also as a suitable material in several areas over a long period of time. However, only recently it has been employed for pharmaceuticals and biomedical applications, particularly as drug delivery vehicles due to properties including selective recognition generated from imprinting the desired analyte, favorable in harsh experimental conditions, and feedback-controlled recognitive drug release. Hence, this review will discuss their synthesis, the reason they are selected as drug delivery vehicles and for their applications in several drug administration routes (i.e. transdermal, ocular and gastrointestinal or stimuli-reactive routes).

Smart drug delivery systems: from fundamentals to the clinic

Smart materials can endow implantable depots, targetable nanocarriers and insertable medical devices with activation-modulated and feedback-regulated control of drug release.

Soft contact lenses for controlled ocular delivery: 50 years in the making

The use of contact lenses as ocular bandages for drug delivery was envisioned nearly 50 years ago by Wichterle and co-workers. Despite the therapeutic advantages that can be obtained, this application has to face up to the poor affinity shown by commercially available contact lenses for most ophthalmic drugs, resulting in small amounts of drug being loaded and short time of therapeutic levels in the eye structures. Novel strategies that appeared in the beginning of 21st century, for example coating lenses with vitamin E, incorporation of drug nanocarriers or application of molecular imprinting technology, are becoming relevant tools for development of true drug/contact lens combination products that may be available for ocular therapy in the foreseeable future.