Health

Polymer in Medical Field

Polymers & materials for the biomedical field

Synthetic polymers have been used for many years in the biomedical field because of their valuable and adjustable characteristics such as biocompatibility, biodegradability, good mechanical properties, etc. SPECIFIC POLYMERS offers a wide range of polymers designed for specific uses in biomedical applications.

THERAGNOSTIC AGENTS

MULTI-FUNCTIONAL POLYMERS FOR THE COATINGS OF NANOPARTICLES

Nanomedicine covers a set of interdisciplinary research at the interface between biology, physics and chemistry. Although polymers were often stigmatized because of the lack of accuracy in their structures in the bio-medical field, recent research highlights a growing interest in functional polymers and copolymers for the implementation of multi-functional nanoparticle coatings that are resistant to protein adsorption and provide high stability, stealth and increased biodistribution in vivo.

For example: polymer coated gadolinium nanoparticles exhibit near-infrared persistent luminescence properties and can be used as in vivo nanotools; biomimetic apatite-based functional nanoparticles have shown interest in diseased cells diagnosis; CeO2 nanoparticles have shown powerful antioxidant properties of interest in experimental stroke. Among these nanoparticles, superparamagnetic iron oxide nanoparticles (SPIONs) are certainly the most promising material for bio-medical applications and have been used extensively in cancer therapy and diagnosis via magnetic targeting or magnetic resonance imaging.

To reach optimal efficiency, these nanoparticles should be coated to improve their biocompatibility, increase their cellular uptake, enhance their circulation and prevent renal clearance. The coating may also be functionalized on their surface with specific moieties to enable the grafting of targeting molecules such as peptides, antibodies or oligoanilines.

11-Phosphonoundecanoic Acid

Poly(ethylene glycol), α-ammonium Chloride, ω-phosphonic Acid

Polymer in medical field at SPECIFIC POLYMERS

Custom design of functional polymers for the conception of theragnostic agents

Poly(ethylene glycol), α-methoxy, ω-phosphonic Acid

Poly(MMA-stat-MAPC1 Acid)

For more than 5 years, SPECIFIC POLYMERS has been working in close collaboration with the Universities of Paris Descartes and Paris Diderot and has developed multi-functional polymers for encapsulating nanoparticles and conferring on them the appropriate set of above-mentioned properties. The common point of all developed polymers is the combination of polyethylene glycol chains known to provide exceptional stability, low cellular uptake, biocompatibility and stealth properties, with phosphonic acid anchoring groups that offer high binding affinity toward metallic atoms. Recent work focused on the combination of both previously mentioned functionalities with a third functional group enabling the grafting of different peptides and offering the prospect of stroke treatment or diagnosis of brain tumors.

BIODEGRADABLE POLYMERS

Biodegradable polymers are a special class of polymer that breaks down through bacterial decomposition process and results in natural by-products (CO2, N2, water, biomass, inorganic salts). Such polymers are currently of great interest for many applications. Such degradable polymers are important for the future of sustainable polymers and plastics, e.g., to resolve the end-of-life of materials and find recyclability routes. SPECIFIC POLYMERS dedicates a significant part of its internal research toward biodegradable polymer in medical field (e.g., for drug and gene delivery, bioengineering scaffolds, sutures, tissue engineering or as bioadhesives) and the design of sustainable thermosets.

FOCUS ON PLA, PGA AND PLGA POLYMERS

In this field, special interest is given to functional polylactic acid (PLA), polyglycolic acid (PGA) or polycaprolactone (PCL) biodegradable polymers, as well as their copolymers with polyethylene glycol (PEG). PLA is a thermoplastic, high-strength, high-modulus polymer. The glass transition temperatures of PLA homopolymers range from 50°C and 80°C. It has lower crystallinity than PGA (35% – 40%). Biomedical use of PLA can be limited by its hydrophobicity which is responsible for low water sorption and thus relatively slow hydrolytic degradation. PLA mechanical properties remain quite high during the first few months in physiological conditions. Compared to PGA, PLA needs ten months to reach a full biodegradation. PGA is a biodegradable thermoplastic polyester characterized by aliphatic ester bonds that are responsible for its hydrolytic instability. The Tg of PGA homopolymers range from 35°C to 40°C. The high crystallinity of PGA (45% – 55%) leads to remarkable mechanical properties (elongation coefficient: 15% – 35%, elastic modulus: 12.5 GPa). The carbonyl groups in PGA can be cleaved under hydrolytic or enzymatic conditions. PGA is fully biodegraded by the body within four months, but its mechanical properties disappear almost completely after six weeks. It is possible to tune the degradation parameters and the mechanical properties of these biodegradable polyesters by combining both lactic and glycolic units within the same poly(lactic acid-co-glycolic acid) PLGA copolymer. The degradation kinetics are heavily dependent on the LA/GA ratio. PLGA copolymers will degrade much faster than corresponding homopolymers. Furthermore, the mechanical properties of PLGA copolymers can be enhanced by increasing the GA content. Finally, a compromise between degradation kinetics and mechanical properties must be reached for each specific application.

PLA diagram SPECIFIC POLYMERS
pga diagram SPECIFIC POLYMERS
PLGA diagram SPECIFIC POLYMERS

AVAILABLE PLA, PGA AND PLGA BASED POLYMERS AND COPOLYMERS
SPECIFIC POLYMERS can synthesize and provide various statistical and block copolymers that combine PLA, PGA or PLGA with other co-monomer (caprolactone, trimethylene carbonate, etc.) or poly(ethylene glycol) (PEG) chains. Copolymers including biocompatible PEG chains and biodegradable PLA chains are of great interest in drug delivery. SPECIFIC POLYMERS is also an expert in the synthesis of functional PLA, PGA and PLGA. Molecular weight, composition (LA/GA ratio) and functionality can be tuned depending on customer specifications.

Poly(ethylene glycol)-Block-

Poly(lactic acid)

Poly(ethylene glycol)-Block-

Poly(lactic-co-glycolic) Acid

Poly(lactic acid),

α-hydroxy, ω-allyl

Poly(lactic acid), α,

ω-bis(methacrylate)

As mentioned in a very interesting review article by Greta Becker and Frederik R. Wurm in Chem. Soc. Rev. (2018, 47, 7739), ring-opening polymerization (ROP) of different cyclic monomers gives access to a variety of polymeric materials with a broad range of different physical properties, e.g., varying hydrophilicity/hydrophobicity, crystallinity, solubility, mechanical strength, degradation behavior or thermal stability.

biodegradable polymers scheme at SPECIFIC POLYMERS

Overview of the systematic order of degradability of some biodegradable polymers

POLYMERS FOR PHOTODYNAMIC THERAPY

Photodynamic therapy (PDT) consists of the simultaneous action of a non-toxic molecule (the photosensitizer), light and oxygen. PDT is popularly used in treating acne, herpes or to treat a wide range of medical conditions, including wet age-related macular degeneration, psoriasis and atherosclerosis. It also treats malignant cancers including head and neck, lung, bladder and particular skin cancers. Below, are some related R&D products that we have developed.

(4-methyl)coumarin-7-yl methacrylate

(4-methyl)coumarin-7-yl Methacrylate Homopolymer

This process, used in dermatology and oncology, is limited owing to the induced photosensitivity of the patients. In this field, SPECIFIC POLYMERS is involved in a project that aspires to improve the efficiency of photosensitizers using tuned polymeric nano-vectors based on photoactive polyoxazolines stabilized by photo-crosslinking, which constitutes an essential step (better stability and enhanced efficiency), as was recently reported in Journal of Materials Chemistry B. To do so, SPECIFIC POLYMERS designs, synthesizes and provides photosensitive monomers and polymers able to create reversible crosslinked networks under UV-light exposure.

POLYMERS FOR DRUG DELIVERY

ARCHITECTURE-CONTROLLED SMART POLYMERS

Polymers play an important role in the advancement of drug delivery technology by providing controlled release of therapeutic agents in constant doses over long periods, cyclic dosage, and tuneable release of both hydrophilic and hydrophobic drugs. Thus, the targeted and controlled release of drugs is currently the subject of a large body of research. Polymeric materials intended for this application need to combine different properties. Amphiphilic and double hydrophilic copolymers enable drug entrapment by self-assembly and the formation of micelles, whereas stimuli-responsive polymers allow controlled drug delivery through exposure to external stimuli (temperature, pH, etc.).

controlled drug delivery scheme

J. Ding et al., Noncovalent interaction-assisted polymeric micelles for controlled drug delivery, Chemical Communication 2014

Poly(lactic acid)-block-poly(ethylene

glycol)-Block-Poly(lactic acid)

PEG α-ammonium

Chloride, ω-phosphonic Acid

Poly(ethylene glycol), α-methoxy,

ω-phosphonic Acid

Poly(PEGMA-

stat-MAA)

Within this field of research, SPECIFIC POLYMERS is able to synthesized a wide range of polymers for combined compatibility with selected drugs, that can be used as a proper carrier in the intended environment and allow enhanced solubility and targeted controlled release. For instance, SPECIFIC POLYMERS can custom design amphiphilic block copolymers by controlled radical polymerization (RAFT, ATRP, NMP, etc.), hydrophilic polymers, biodegradable block copolymers, environmentally responsive/smart polymers, dendrimer polymers. We also have the ability to provide various building-blocks for the synthesis of hydrogel networks or other crosslinked materials.

DENTISTRY, IMPLANT MATERIALS, OPHTHALMOLOGY

PHOSPHORUS CONTAINING POLYMERS

Apart from the application mentioned in the previous sections, SPECIFIC POLYMERS also uses its expertise in functional polymer synthesis for other applications in the medical field. For instance, dental and implant materials need excellent mechanical and adhesion performance associated with biostability. Building blocks and polymers containing phosphonic acid functions are especially dedicated to this application, because of their ability in binding to bones and various calcium phosphates.

Essentially, SPECIFIC POLYMERS has solid experience and a large R&D product portfolio of phosphorus containing monomers and polymers of interest to the biomedical field. In addition, UV-curable materials are also widely employed in the field of dentistry and we offer a wide range of monomers and building-blocks bearing UV-reactive moieties such as acrylate, epoxy or maleimides.

MAPC1

Acid

Poly(MMA-stat-

MAPC1 Acid)

Poly(ethylene glycol), α-methoxy,

ω-phosphonic Acid

Poly(ethylene glycol), α,

ω-bis(phosphonic acid)

SPECIFIC POLYMERS also offers functional polymers of interest in the field of ophthalmology, especially for producing contact lenses. Such materials must combine specific features such as hydrophilicity, oxygen permeability and the ability to form hydrogel structures via functional groups.

Poly(MMA-stat-HEMA)

Poly(HEMA)

Poly(HEMA-stat-MAA)

What a pleasure to hear from you!

Do not hesitate to contact us if you require more information or if you have any question on our expertise in the health field.