Visible light-curable polymers for biomedical applications

Photocurable systems, which offer advantages such as microfabrication and in situ fabrication, have been widely used as dental restorative materials. Because the visible light-curable (VLC) system causes no biological damage, it is popular as a dental material and is being investigated by many researchers for other medical applications. Here, the principle of the VLC system is explained and recent progress in key components including photoinitiators, monomers, macromers, and prepolymers is discussed. Finally, biomedical applications for drug delivery and soft tissue engineering are reviewed. Considering the recent development of VLC systems, its importance in the field of medical applications is expected to continue to increase in the future.     

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).     

Surface structure of polymers for biomedical applications

Biological reactions with synthetic polymers are strongly influenced by the surfaces of those materials. The surfaces are often substantially different in composition and structure from the bulk. By using contemporary surface analysis methods, we can understand polymer surfaces. The surfaces of polymers can also be modified to generate desired biological responses. These points are illustrated with examples involving polyurethanes and RF plasma-deposited films.     

Malolactonate polymers and copolymers for biomedical applications

A new class of malolactonate polymers and copolymers with a wide range of lateral chain structures were synthesized by anionic ring opening polymerization of alkyl malolactonate monomers. The monomers were prepared in good yields according to established procedures. Final macromolecular and thermal characteristics were in agreement with the designed monomer structures. Molecular weights in the range 4-20 kD were attained, as a result of chain transfer reactions. Representative polymeric compounds displayed stability up to 200 °C. Many of the obtained poly(alkyl malolactonate)s were able to sustain and promote with 3T3 murine fibroblasts adhesion and proliferation onto their surface.     

Molecular design of biologically active biodegradable polymers for biomedical applications

The objective of this research is to synthesize synthetic biodegradable polymers that would have biological functions similar to nitric oxide. Polyglycolide (PGA) was the synthetic biodegradable polymer and 4-amino-2,2,6,6-tetramethylpiperidine-1-oxy (Tempamine) was chosen as the source of nitroxyl radicals. Tempamine nitroxyl radicals were chemically incorporated into the carboxylic acid chain ends of PGA macromolecules via amide linkage. The kinetics of in vitro hydrolytic release of Tempamine nitroxyl radicals from the host PGA in buffered media at 37 °C was studied. Tempamine nitroxyl radicals were released into the media via cleavage of either ester linkages in the PGA segments or/and the amide linkage between Tempamine and the PGA segments. The duration of hydrolysis would determine the type of degradation products that were different in the segmental length of the PGA component. A preliminary in vitro cell culture study of this new generation of biologically active biodegradable polymers indicated that it was able to retard the proliferation of smooth muscle cells as pure nitric oxide does.     

Recent developments in oriented polymers for biomedical and engineering applications

A review is presented of recent research at Leeds University which has been directed at devising novel methods for the production of oriented polymer structures. First, the new hot compaction process for oriented fibre and tapes is described, together with its applications to polyethylene and polypropylene where there are a number of practical developments. Secondly, there is the use of hydrostatic extrusion to make load bearing oriented products from hydroxyapatite filled polyethylenes. The production routes include the application of high pressure annealing prior to hydrostatic extrusion and the preparation of high modulus polyethylene fibre/hydroxyapatite billets as the starting point. Finally, recent progress on die-drawing as a means to producing oriented monofilaments and biaxially oriented tubes is described, where the applications include polymer ropes, pipes for gas and water distribution and transparent cans for packaging.     

Aconityl-derived polymers for biomedical applications. Modeling study of cis–trans isomerisation

 Soluble polymers have been prepared that are designed to undergo enhanced rates of hydrolysis at pH values less than that observed in blood circulation. The degradable element in the polymer mainchain is derived from cis-aconityl acid and is defined by a carboxylic acid pendent functionality (C-4) that is cis across a double bond to an amide at C-1 in the polymer mainchain. While degradation studies in vitro have confirmed these polymers do undergo enhanced rates of degradation at acidic pH values, there is also increasing evidence that during the degradation process the double bond isomerises to the trans configuration and thus prevents the full degradation of a polymer. From a molecular modelling perspective we are seeking to understand the propensity for this cis–trans isomerisation and the mechanism of this cis–trans isomerisation is discussed. Received: 29 April 2002 / Accepted: 6 September 2002 / Published online: 14 February 2003     

Glyconanoparticles for biomedical applications

Over the past two decades, glycosylated nanoparticles (i.e., glyconanoparticles having sugar residues on the surface) received much attention for biomedical applications such as bioassays and targeted drug delivery. This minireview focuses on three aspects: (1) glycosylated gold nanoparticles, (2) glycosylated quantum dots, and (3) glyconanoparticles self-assembled from amphiphilic glycopolymers. The synthetic methods and the multivalent interactions between glyconanoparticles and lectins is shortly illustrated.     

Characterization of keratin–collagen 3D scaffold for biomedical applications

Fabrication of keratin–collagen (KC) 3D scaffold with improved thermal denaturation rate is reported. In vitro application of (KC) scaffold stimulates basic extra cellular matrix constituents. KC Scaffold considerably reduced undesirable properties of both collagen and keratin while collagen incorporation reduces the fragility with increases of strength and flexibility in the scaffold. In addition to this, the scaffold showed homogenous well‐interconnected pores in the range of 10–100 µm when observed in scanning electron microscope. Usage of keratin in KC scaffold offers increased biodegradation rate and higher denaturation rate in addition to its rapid cell growth with normal morphology ultimately reaching cell population of 3.9–9.7 million per cm³ after 48 hr in KC scaffold. Circular dichroism (CD) and Fourier transform spectroscopy (FT‐IR) of KC showed presence of helical structure of collagen and ß‐turns of keratin confirming retention of native structures of both the proteins KC scaffold showed good swelling behavior and water uptake. Our study strongly supports the superidity of KC scaffold over the collagen or keratin when they are independently used for tissue engineering applications. Copyright © 2011 John Wiley & Sons, Ltd.     

Topological effects of macrocyclic polymers:from precise synthesis to biomedical applications

Polymer chain architectures play a crucial role in the physical properties of polymers and this unique phenomenon has been recognized as the topological effects.As one of the most representative architectures,macrocyclic polymers characterized by the endless topology have received extensive attention due to their distinct physical properties as compared to the linear counterparts.To understand these differences and unravel the underlying mechanisms,there is a long pursuit to efficiently fabricate macrocyclic polymers.To date,both ring-closing and ring-expansion strategies have been developed,which drastically elevates the accessibility of macrocyclic polymers.The improved availability of macrocyclic polymers enables the further investigation of the biomedical applications and the preliminary results suggest that macrocyclic polymers outperform their linear analogs in terms of improving gene delivery efficiency,elevating blood circulation time,and enhancing colloidal stability of nanoparticles.     

New polymers for biomedical applications: Synthesis and characterization of acrylic systems with pharmacological activity

The synthesis and characterization of new biocompatible “Polymeric Drugs” on the basis of poly (methacrylic esters) and poly (methacrylamides) with side substituents of pharmacological interest, with analgesic, antiinflammatory, antipyretic and antiaggregating activities, is reported. The preparation of these systems was carried out following the universal model suggested by Ringsdorf, and the polymers prepared by the free radical polymerization of the corresponding acrylic monomers were characterized by ¹H- and ¹³C-NMR spectroscopies. Biocompatible hydrogels were prepared by free radical copolymerization of these monomers with HEMA. The characteristic copolymerization parameters and the microstructural distribution of comonomeric sequences were determined by NMR spectroscopy. The swelling behaviour of copolymer films was followed gravimetrically. Applications of polymer and copolymer systems are being tested in the fields of pharmacology and vascular surgery.     

Spintronic platforms for biomedical applications

Since the fundamental discovery of the giant magnetoresistance many spintronic devices have been developed and implemented in our daily life (e.g. information storage and automotive industry). Lately, advances in the sensors technology (higher sensitivity, smaller size) have potentiated other applications, namely in the biological area, leading to the emergence of novel biomedical platforms. In particular the investigation of spintronics and its application to the development of magnetoresistive (MR) biomolecular and biomedical platforms are giving rise to a new class of biomedical diagnostic devices, suitable for bench top bioassays as well as point-of-care and point-of-use devices. Herein, integrated spintronic biochip platforms for diagnostic and cytometric applications, hybrid systems incorporating magnetoresistive sensors applied to neuroelectronic studies and biomedical imaging, namely magneto-encephalography and magneto-cardiography, are reviewed. Also lab-on-a-chip MR-based platforms to perform biological studies at the single molecule level are discussed. Overall the potential and main characteristics of such MR-based biomedical devices, comparing to the existing technologies while giving particular examples of targeted applications, are addressed.     

Acoustic nanodrops for biomedical applications

Acoustic nanodrops are designed to vaporize into ultrasound-responsive microbubbles, which present certain challenges nonexistent for conventional nanoemulsions. The requirements of biocompatibility, vaporizability, and colloidal stability have focused research on perfluorocarbons. Shorter perfluorocarbons yield better vaporizability via their lower critical temperature, but they also dissolve more easily owing to their higher vapor pressure and solubility. Thus, acoustic nanodrops have required a trade-off between vaporizability and colloidal stability in vivo. The recent advent of vaporizable endoskeletal droplets, which are both colloidally stable and vaporizable, may have solved this problem. The purpose of this review is to justify this premise by pointing out the beneficial properties of acoustic nanodrops, providing an analysis of vaporization and dissolution mechanisms, and reviewing current biomedical applications.     

Emissive metallacages for biomedical applications

Owing to their appealing three-dimensional structures and tunable photophysical properties, emissive metallacages have been widely applied in recognition and sensing, adsorption and separation, catalysis, etc. Recently, the application of emissive metallacages in biomedical fields has emerged as a hot research topic, because multiple biological functionalities can be facilely integrated into metallacage-based platforms to deliver different functions. In this review, the applications of emissive ...     

Recent progress on cyclic polymers: Synthesis,bioproperties, and biomedical applications

Polymer topologies exert a significant effect on its properties, and polymer nanostructures with advanced architectures, such as cyclic polymers, star‐shaped polymers, and hyperbranched polymers, are a promising class of materials with advantages over conventional linear counterparts. Cyclic polymers, due to the lack of polymer chain ends, have displayed intriguing physical and chemical properties. Such uniqueness has drawn considerable attention over the past decade. The current review focuses on the recent progress in the design and development of cyclic polymer with an emphasis on its synthesis and bio‐related properties and applications. Two primary synthetic strategies towards cyclic polymers, that is, ring‐expansion polymerization and ring‐closure reaction are summarized. The bioproperties and biomedical applications of cyclic polymers are then highlighted. In the end, the future directions of this rapidly developing research field are discussed. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 1447–1458     

Cyclic polymers: Advances in their synthesis,properties, and biomedical applications

Since the time first synthetic macrocycles were observed as academic curiosities, great advances have been made. Thanks to the development of controlled polymerization processes, new catalytic systems and characterization techniques during the last decades, well-defined cyclic polymers are now readily accessible. This further permits the determination of their unique set of properties, mainly due to their lack of chain ends, and their use for industrial applications can now be foreshadowed. This review aims to give an overview on the recent progresses in the field of ring polymers to this day. The current state of the art of the preparation of cyclic polymers, the challenges related to it such as the purification of the samples and the scalability of the synthetic processes, the properties arising from the cyclic topology and the potential use of cyclo-based polymers for biomedical applications are as many topics covered in this review.     

Surface modification of biomedical polymers

Surface modification of biomedical polymers by the technique of surface grafting was briefly overviewed, mostly based on our results. It was shown that surface grafting of water-soluble polymer chains onto polymeric biomaterials was effective in producing mechanically non-stimulative, blood-compatible, antibacterial, tissue-bonding, and cell-adhesive surfaces. In addition to the improvement of the interfacial biocompatibility, the surface grafting was useful also for obtaining a biofunctional surface such as immunoadsorbent.     

Quantum dots-hydrogel composites for biomedical applications

Quantum dots-hydrogel composites are promising new materials that have attracted extensive attention due to their incomparable biocompatibility and acceptable biodegradability, leading to enormous potential applications for various fields. This review summarizes the recent advances in quantum dots-hydrogel composites with a focus on synthesis methods, including hydrogel gelation in quantum dots(QDs) solution, embedding prepared QDs into hydrogels after gelation, forming QDs in situ within the pr...