A facile strategy for fabricating PCL/PEG block copolymer with excellent enzymatic degradation

Progress of biodegradable polymer application in cardiac occluders

Cardiac septal defect is the most prevalent congenital heart disease and is typically treated with open-heart surgery under cardiopulmonary bypass. Since the 1990s, with the advancement of interventional techniques and minimally invasive transthoracic closure techniques, cardiac occluder implantation represented by the Amplazter products has been the preferred treatment option. Currently, most occlusion devices used in clinical settings are primarily composed of Nitinol as the skeleton. Nevertheless, long-term follow-up studies have revealed various complications related to metal skeletons, including hemolysis, thrombus, metal allergy, cardiac erosion, and even severe atrioventricular block. Thus, occlusion devices made of biodegradable materials have become the focus of research. Over the past two decades, several bioabsorbable cardiac occluders for ventricular septal defect and atrial septal defect have been designed and trialed on animals or humans. This review summarizes the research progress of bioabsorbable cardiac occluders, the advantages and disadvantages of different biodegradable polymers used to fabricate occluders, and discusses future research directions concerning the structures and materials of bioabsorbable cardiac occluders.

Mechanical and biodegradability of porous PCL/PEG copolymer-reinforced cellulose nanofibers for soft tissue engineering applications

The design and development of a new class of biomaterial has gained particular interest in producing polymer scaffold for biomedical applications. Mechanical properties, biological and controlling pores scaffold of the biomaterials are important factors to encourage cell growth and eventual tissue repair and regeneration. In this study, poly-ε-caprolactone (PCL) /polyethylene glycol (PEG) copolymer (80/20) incorporated with CNF scaffolds were made employing solvent casting and particulate leaching methods. Four mass percentages of CNF (1, 2.5, 5, and 10 wt.%) were integrated into the copolymer through a silane coupling agent. Mechanical properties were determined using Tensile Tester data acquisition to investigate the effect of porosity, pore size, and CNF contents. Tensile strength obtained for PCL/PEG- 5 wt.% CNF was 16 MPa, which drastically decreased after creating a porous structure to 7.1 MPa. The optimum parameters of the results were found to be 5 wt.% for CNF, 240 μm for pore size, and 83% for porosity. Scanning electron microscopy (SEM) micrograph reveals that consistent pore size and regular pore shape were accomplished after the addition of CNF-5 wt.% into PCL/PEG. The results of mass loss of PCL/PEG reinforced-CNF 1 % have clearly enhanced to double values compared with PCL/PEG copolymer and three times with PCL/PEG scaffold-CNF 1 %. In addition, all PCL/PEG reinforced and scaffold- CNF were partially disintegrated under composting conditions confirming their biodegradable behavior. This also provides a possible solution for the end life of these biomaterials.

Resorbable Biomaterials Used for 3D Scaffolds in Tissue Engineering: A Review

This article provides a thorough overview of the available resorbable biomaterials appropriate for producing replacements for damaged tissues. In addition, their various properties and application possibilities are discussed as well. Biomaterials are fundamental components in tissue engineering (TE) of scaffolds and play a critical role. They need to exhibit biocompatibility, bioactivity, biodegradability, and non-toxicity, to ensure their ability to function effectively with an appropriate host response. With ongoing research and advancements in biomaterials for medical implants, the objective of this review is to explore recently developed implantable scaffold materials for various tissues. The categorization of biomaterials in this paper includes fossil-based materials (e.g., PCL, PVA, PU, PEG, and PPF), natural or bio-based materials (e.g., HA, PLA, PHB, PHBV, chitosan, fibrin, collagen, starch, and hydrogels), and hybrid biomaterials (e.g., PCL/PLA, PCL/PEG, PLA/PEG, PLA/PHB PCL/collagen, PCL/chitosan, PCL/starch, and PLA/bioceramics). The application of these biomaterials in both hard and soft TE is considered, with a particular focus on their physicochemical, mechanical, and biological properties. Furthermore, the interactions between scaffolds and the host immune system in the context of scaffold-driven tissue regeneration are discussed. Additionally, the article briefly mentions the concept of in situ TE, which leverages the self-renewal capacities of affected tissues and highlights the crucial role played by biopolymer-based scaffolds in this strategy.

Toward regulating biodegradation in stages of polyurethane copolymers with bicontinuous microphase separation

For typical biodegradable polymers, their overall performance almost declines exponentially to the degradation degree, which inevitably leads to a dilemma between the requirements of service life and retention time in the environment (both in vitro and in vivo). It is a great challenge to develop a biodegradable polymeric device with relatively stable performance in service while rapidly degrading out of service. Herein, we demonstrate an effective strategy to control degradation of biodegradable polymers in stages by constructing separated bicontinuous microphases with very different microphase degradation rates. First, polyurethane copolymers (PCL-b-CrP-U) containing two blocks, i.e., semicrystalline poly(ε-caprolactone) (PCL) blocks and amorphous random copolymer blocks (CrP) based on ε-CL and p-dioxanone (PDO), were synthesized. The microscopic morphology of PCL-b-CrP-U is investigated by an alkali-accelerated degradation experiment, which also demonstrates that the chain cleavage-induced crystallization during degradation resulted in a self-reinforcement by forming degradation residues with a scaffold-like morphology. The tensile test shows that PCL-b-CrP-U has excellent mechanical properties (1500% of elongation at break, a tensile strength of about 7.5 MPa, and an elastic modulus of 40.0 MPa). The degradation experiments with artificial pancreatic juice as a working medium reveal that PCL-b-CrP-U samples containing relatively high PDO units exhibit a three-stage degradation, i.e. an induction stage, a steady degradation stage and an accelerated degradation stage. The CrP phase preferentially hydrolyzes to form some microchannels due to its amorphous nature and relatively high hydrophilicity, effectively accelerating the entry of water and enzymes into the inner parts of the sample. Meanwhile, at this stage, those originally amorphous PCL segments gradually crystalize owing to their enhanced chain mobility induced by the chain cleavage, forming a "scaffold"-like structure, which effectively reinforces the sample to resist the damage from external force and therefore guarantees a relatively stable mechanical performance of PCL-b-CrP-U during service. With the further depletion of the CrP phase, the intermediate "scaffold"-like structure is also very beneficial to accelerate the degradation of residues owing to its large specific surface area, which is expected to be beneficial for preventing long-term retention of the implantation devices.

From nano to the macro: tuning hierarchical aggregation of thermoresponsive PEG/PCL-based polyurethanes via molar mass/composition control

Amphiphilic hyperbranched polyurethanes (HPUs) based on PEG and PCL are promising for several biomedical applications. However, the lack of control over the molar mass and composition hinders a deep understanding of the aqueous self-assembly of HPUs. In this paper, the control over the HPU molar mass and composition was provided by dynamic urea bond-mediated polymerization (DUBMP), enabling a careful evaluation of their aqueous self-assembly by 1H NMR, DLS, and Cryo-TEM. HPUs containing a single PCL block per chain self-assemble into nanoaggregates (Rh ≈ 10 nm) in water up to its cloud-point temperature (Tcp) of 34 °C. On the other hand, HPUs with more than one PCL block per chain self-assemble into nanoaggregates and their clusters below Tcp. In this case, the solution behavior can be tuned by the HPU molar mass. Increasing $$\overline{{\mathrm{M} }_{\mathrm{w}}}$$ M w ¯ from 4 to 19 kDa, HPUs of similar composition can form colloidally stable cluster suspensions ($$\overline{{\mathrm{M} }_{\mathrm{w}}}$$ M w ¯ = 4 kDa) and phase separate into a denser liquid aggregate–cluster phase ($$\overline{{\mathrm{M} }_{\mathrm{w}}}$$ M w ¯ = 7 kDa) or into a highly viscous aggregate-network phase ($$\overline{{\mathrm{M} }_{\mathrm{w}}}$$ M w ¯ = 19 kDa). This type of control over the hierarchical aggregation of HPUs was reported for the first time and is interesting for biomedical applications.

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Nanomaterials based on thermosensitive polymer in biomedical field

The progress of nanotechnology enables us to make use of the special properties of materials on the nanoscale and open up many new fields of biomedical research. Among them, thermosensitive nanomaterials stand out in many biomedical fields because of their “intelligent” behavior in response to temperature changes. However, this article mainly reviews the research progress of thermosensitive nanomaterials, which are popular in biomedical applications in recent years. Here, we simply classify the thermally responsive nanomaterials according to the types of polymers, focusing on the mechanisms of action and their advantages and potential. Finally, we deeply investigate the applications of thermosensitive nanomaterials in drug delivery, tissue engineering, sensing analysis, cell culture, 3D printing, and other fields and probe the current challenges and future development prospects of thermosensitive nanomaterials.

Folic acid-conjugated magnetic triblock copolymer nanoparticles for dual targeted delivery of 5-fluorouracil to colon cancer cells

Background

In the current study, folic acid-conjugated PEG-PCL-PEG triblock copolymer were synthesized and loaded with 5-fluorouracil and magnetite nanoparticles (5-FU-SPION-PEG-PCL-PEG-FA) for targeted delivery of drug to HT29 human colon cancer cells and CT26 mouse colon cancer model. The nanoparticles were synthesized and characterized by nuclear magnetic resonance spectroscopy (NMR) and transmission electron microscopy (TEM). The cellular uptake of nanoparticles was assessed in vitro (on HUVEC and HT29) and in vivo (on CT26 colon tumor tissues). The cytotoxic effect of nanoparticles was assessed on human colon cell lines (HT29, Caco-2, HTC116, and SW480) and normal HUVEC cells. In addition, antitumor effects of nanoparticles were investigated based on tumor volume, survival time and protein expression of Bax and Bcl-2 on CT26 tumor-bearing BALB/c mice.

Results

Characterization of nanoparticles showed 5-FU-SPION-PEG-PCL-PEG-FA (5-FU-NPs-FA) nanoparticles had spherical shape with hydrodynamic diameter of 85 nm. The drug-release profile exhibited sustained pH-responsive release with cumulative release reaching approximately 23% after 24 h. Cellular uptake studies revealed that HT29 cancer cells absorb higher amount of 5-FU-NPs-FA as compared to HUVEC normal cells (P < 0.05). In addition, 5-FU-NPs-FA was found to be more antitumor efficient in comparison to free 5-FU based on Bax/Bcl2 ratio, survival rate of tumoral mouse and inhibitory tumor volume (P < 0.05).

Conclusions

The results suggested that 5-FU-NPs-FA could be considered as promising sustained drug delivery platform for in vitro and in vivo conditions, which may provide selective treatment of tumor cancer cells.

Graphical Abstarct

Nature-Derived and Synthetic Additives to poly(ɛ-Caprolactone) Nanofibrous Systems for Biomedicine; an Updated Overview

As a low cost, biocompatible, and bioresorbable synthetic polymer, poly (ɛ-caprolactone) (PCL) is widely used for different biomedical applications including drug delivery, wound dressing, and tissue engineering. An extensive range of in vitro and in vivo tests has proven the favourable applicability of PCL in biomedicine, bringing about the FDA approval for a plethora of PCL made medical or drug delivery systems. This popular polymer, widely researched since the 1970s, can be readily processed through various techniques such as 3D printing and electrospinning to create biomimetic and customized medical products. However, low mechanical strength, insufficient number of cellular recognition sites, poor bioactivity, and hydrophobicity are main shortcomings of PCL limiting its broader use for biomedical applications. To maintain and benefit from the high potential of PCL, yet addressing its physicochemical and biological challenges, blending with nature-derived (bio)polymers and incorporation of nanofillers have been extensively investigated. Here, we discuss novel additives that have been meant for enhancement of PCL nanofiber properties and thus for further extension of the PCL nanofiber application domain. The most recent researches (since 2017) have been covered and an updated overview about hybrid PCL nanofibers is presented with focus on those including nature-derived additives, e.g., polysaccharides and proteins, and synthetic additives, e.g., inorganic and carbon nanomaterials.

The Influence of Polymer Composition on the Hydrolytic and Enzymatic Degradation of Polyesters and Their Block Copolymers with PDMAEMA

Well-defined, semi-degradable polyester/polymethacrylate block copolymers, based on ε-caprolactone (CL), d,l-lactide (DLLA), glycolide (GA) and N,N'-dimethylaminoethyl methacrylate (DMAEMA), were synthesized by ring-opening polymerization (ROP) and atom transfer radical polymerization. Comprehensive degradation studies of poly(ε-caprolactone)-block-poly(N,N'-dimethylaminoethyl methacrylate) (PCL-b-PDMAEMA) on hydrolytic degradation and enzymatic degradation were performed, and those results were compared with the corresponding aliphatic polyester (PCL). The solution pH did not affect the hydrolytic degradation rate of PCL (a 3% M_n loss after six weeks). The presence of a PDMAEMA component in the copolymer chain increased the hydrolysis rates and depended on the solution pH, as PCL-b-PDMAEMA degraded faster in an acidic environment (36% M_n loss determined) than in a slightly alkaline environment (27% M_n loss). Enzymatic degradation of PCL-b-PDMAEMA, poly(d,l-lactide)-block-poly(N,N'-dimethylaminoethyl methacrylate) (PLA-b-PDMAEMA) and poly(lactide-co-glycolide-co-ε-caprolactone)-block-poly(N,N'-dimethylaminoethyl methacrylate) (PLGC-b-PDMAEMA) and the corresponding aliphatic polyesters (PCL, PLA and PLGC) was performed by Novozyme 435. In enzymatic degradation, PLGC degraded almost completely after eleven days. For polyester-b-PDMAEMA copolymers, enzymatic degradation primarily involved the ester bonds in PDMAEMA side chains, and the rate of polyester degradation decreased with the increase in the chain length of PDMAEMA. Amphiphilic copolymers might be used for biomaterials with long-term or midterm applications such as nanoscale drug delivery systems with tunable degradation kinetics.

Coaxial electrospun biomimetic copolymer fibres for application in diffusion magnetic resonance imaging

Objective. The use of diffusion magnetic resonance imaging (dMRI) opens the door to characterizing brain microstructure because water diffusion is anisotropic in axonal fibres in brain white matter and is sensitive to tissue microstructural changes. As dMRI becomes more sophisticated and microstructurally informative, it has become increasingly important to use a reference object (usually called an imaging phantom) for validation of dMRI. This study aims to develop axon-mimicking physical phantoms from biocopolymers and assess their feasibility for validating dMRI measurements.Approach. We employed a simple and one-step method-coaxial electrospinning-to prepare axon-mimicking hollow microfibres from polycaprolactone-b-polyethylene glycol (PCL-b-PEG) and poly(D, L-lactide-co-glycolic) acid (PLGA), and used them as building elements to create axon-mimicking phantoms. Electrospinning was firstly conducted using two types of PCL-b-PEG and two types of PLGA with different molecular weights in various solvents, with different polymer concentrations, for determining their spinnability. Polymer/solvent concentration combinations with good fibre spinnability were used as the shell material in the following co-electrospinning process in which the polyethylene oxide polymer was used as the core material. Following the microstructural characterization of both electrospun and co-electrospun fibres using optical and electron microscopy, two prototype phantoms were constructed from co-electrospun anisotropic hollow microfibres after inserting them into water-filled test tubes.Main results. Hollow microfibres that mimic the axon microstructure were successfully prepared from the appropriate core and shell material combinations. dMRI measurements of two phantoms on a 7 tesla (T) pre-clinical scanner revealed that diffusivity and anisotropy measurements are in the range of brain white matter.Significance. This feasibility study showed that co-electrospun PCL-b-PEG and PLGA microfibre-based axon-mimicking phantoms could be used in the validation of dMRI methods which seek to characterize white matter microstructure.

Sustainable cultivation of Navicula incerta using cellulose-based scaffold incorporated with nanoparticles in air-liquid interface cultivation system

Microalgae cultivation using open cultivation systems requires large area and it is susceptible to contamination as well as weather changes. Meanwhile, the closed systems require large capital investment, and they are susceptible to the build-up of dissolved oxygen. Air-liquid interface culture systems with low water-footprint, but high packing density can be used for microalgae cultivation if low-cost culture scaffolds are available. In this study, cellulose-based scaffolds were synthesized using NaOH/urea aqueous solution as the solvent. Titanium dioxide (TiO₂), silica gel and polyethylene glycol 1000 (PEG 1000) nanoparticles were added into the membrane scaffolds to increase the hydrophilicity of nutrient absorbing to support the growth of microalgae. The membrane scaffolds were characterized by FTIR, SEM, contact angle, porosity and porometry. All three nanoparticles additives showed their ability in reducing the contact angle of membrane scaffolds from 63.4 ± 2.3° to a range of 52.6 ± 1.2° to 38.8 ± 1.5° due to the hydrophilic properties of the nanoparticles. The decreasing in pore size when nanoparticles were added did not affect the porosity of membrane scaffolds. Cellulose membrane scaffold with TiO₂ showed the highest percentage of microalgae Navicula incerta growth rate of 22.1% because of the antibacterial properties of TiO₂ in lowering the risk of cell contamination and enhancing the growth of N. incerta. The results exhibited that cellulose-based scaffold with TiO₂ added could be an effective support in plant cell culture field.

Amphiphilic copolymers in biomedical applications: Synthesis routes and property control

The request of new materials, matching strict requirements to be applied in precision and patient-specific medicine, is pushing for the synthesis of more and more complex block copolymers. Amphiphilic block copolymers are emerging in the biomedical field due to their great potential in terms of stimuli responsiveness, drug loading capabilities and reversible thermal gelation. Amphiphilicity guarantees self-assembly and thermoreversibility, while grafting polymers offers the possibility of combining blocks with various properties in one single material. These features make amphiphilic block copolymers excellent candidates for fine tuning drug delivery, gene therapy and for designing injectable hydrogels for tissue engineering. This manuscript revises the main techniques developed in the last decade for the synthesis of amphiphilic block copolymers for biomedical application. Strategies for fine tuning the properties of these novel materials during synthesis are discussed. A deep knowledge of the synthesis techniques and their effect on the performance and the biocompatibility of these polymers is the first step to move them from the lab to the bench. Current results predict a bright future for these materials in paving the way towards a smarter, less invasive, while more effective, medicine.

Synthesis of zwitterionic chimeric polymersomes for efficient protein loading and intracellular delivery

Design and synthesis of degradable chimeric polymersomes based on zwitterionic PAC(DMA)-PCL-PMDMSA triblock copolymers for high protein loading and intracellular delivery.

Strategies for the synthesis of block copolymers with biodegradable polyester segments

Oxygenated block copolymers with biodegradable polyester segments can be prepared in one-pot through sequential or simultaneous addition of monomers. This review highlights the state of the art in this area.

Progress and Prospects of Polymer-Based Drug Delivery Systems for Bone Tissue Regeneration

Despite the high regenerative capacity of bone tissue, there are some cases where bone repair is insufficient for a complete functional and structural recovery after damage. Current surgical techniques utilize natural and synthetic bone grafts for bone healing, as well as collagen sponges loaded with drugs. However, there are certain disadvantages associated with these techniques in clinical usage. To improve the therapeutic efficacy of bone tissue regeneration, a number of drug delivery systems based on biodegradable natural and synthetic polymers were developed and examined in in vitro and in vivo studies. Recent studies have demonstrated that biodegradable polymers play a key role in the development of innovative drug delivery systems and tissue engineered constructs, which improve the treatment and regeneration of damaged bone tissue. In this review, we discuss the most recent advances in the field of polymer-based drug delivery systems for the promotion of bone tissue regeneration and the physical-chemical modifications of polymers for controlled and sustained release of one or more drugs. In addition, special attention is given to recent developments on polymer nano- and microparticle-based drug delivery systems for bone regeneration.

Synthesis of biodegradable protein–poly(ε-caprolactone) conjugates via enzymatic ring opening polymerization

Lipase–poly(HEAA) conjugates act as initiators and catalysts simultaneously for the eROP of ε-CL, forming biodegradable conjugates with amphiphilic graft copolymers.

Fabrication of fibrillated and interconnected porous poly(ε-caprolactone) vascular tissue engineering scaffolds by microcellular foaming and polymer leaching

This paper provides a method combining eco-friendly supercritical CO₂ microcellular foaming and polymer leaching to fabricate small-diameter vascular tissue engineering scaffolds.

Chitosan/poly(ε-caprolactone)-block-poly(ethylene glycol) copolymer electrospun membrane for the adsorption of dyes

The CS/PCL-(b-PEG) nanofibers with controllable core to shell ratio were fabricated as an adsorbent for dye adsorption.

Insoluble and Thermostable Polyhydroxyesters From a Renewable Natural Occurring Polyhydroxylated Fatty Acid

To explore the potential of long chain polyhydroxyalkanoates as non-toxic food packaging materials, the characterization of polyesters prepared from a natural occurring polyhydroxylated C16 carboxylic acid (9,10,16-trihydroxyhexadecanoic or aleuritic acid) has been addressed. Such monomer has been selected to elucidate the reactivity of primary and secondary hydroxyl groups and their contribution to the structure and properties of the polyester. Resulting polyaleuritate films have been produced using an open mold in one-step, solvent-free self-polycondensation in melt state and directly in air to evaluate the effect of oxygen in their final physical and chemical properties. These polymers are amorphous, insoluble, and thermostable, being therefore suitable for solvent, and heat resistant barrier materials. Structurally, most of primary hydroxyls are involved in ester bonds, but there is some branching arising from the partial participation of secondary O-H groups. The oxidative cleavage of the vicinal diol moiety and a subsequent secondary esterification had a noticeable effect on the amorphization and stiffening of the polyester by branching and densification of the ester bond network. A derivation of such structural modification was the surface compaction and the reduction of permeability to water molecules. The addition of Ti(OiPr)₄ as a catalyst had a moderate effect, likely because of a poor diffusion within the melt, but noticeably accelerated both the secondary esterification and the oxidative processes. Primary esterification was a high conversion bulk reaction while oxidation and secondary esterification was restricted to nearby regions of the air exposed side of cast films. The reason was a progressive hindering of oxygen diffusion as the reaction progresses and a self-regulation of the altered layer growth. Despite such a reduced extent, the oxidized layer noticeably increased the UV-vis light blockage capacity. In general, characterized physical properties suggest a high potential of these polyaleuritate polyesters as food preserving materials.

A review of emerging bone tissue engineering via PEG conjugated biodegradable amphiphilic copolymers

Defects in bones can be caused by a plethora of reasons, such as trauma or illness, and in many cases, it poses challenges to the current treatment approaches for bone repair. With increasing demand of bone bioengineering in tissue transplant, there is a need to source for sustainable solutions to induce bone regeneration. Polymeric biomaterials have been identified as a promising approach due to its excellent biocompatibility and controllable biodegradability. Specifically, poly(ethylene glycol) (PEG) is one of the most commonly investigated polymer for use in bio-related application due to its bioinertness and versatility. Furthermore, the hydrophilic nature enables it to be incorporated with hydrophobic but biodegradable polymers like, polylactide (PLA) and polycaprolactone (PCL), to create an amphiphilic polymer. This article reviews the recent synthetic strategies available for the construction of PEG conjugated polymeric system, analysis of PEG influence on the material properties, and provides an overview of its application in bone engineering.

Preparation of fluorinated PCL porous microspheres and a super-hydrophobic coating on fabrics via electrospraying

In this study, fluorinated polycaprolactone (PCL) block polymers with different fluorine contents were synthesized via atom transfer radical polymerization (ATRP). An electrospraying technique was used to prepare fluorinated PCL microspheres with different microstructures. In contrast to the golf ball shape of unmodified PCL microspheres displaying porous pits on the surface, block polymer PCL-PTFOA(2 h) and PCL-PTFOA(6 h) microsphere surfaces displayed regular honeycomb-like pore structures. Thermally induced and evaporation-induced phase separations are proposed as the main mechanisms involved in the formation of the porous microstructures. The micro-phase separation between the two blocks of the fluorinated PCL copolymer is another factor that promoted the uniform collapse on the microsphere surface and the formation of its rugged wall. The surface roughness of the porous microspheres significantly improved their hydrophobicity, generating coating contact angles on aluminium foil substrates that measured as high as 162.4 ± 1.5°, which revealed that the surfaces were super-hydrophobic. Lastly, cotton fabric was directly coated with the fluorinated polymer microspheres via electrospraying, resulting in super-hydrophobic surfaces and CAs reaching 160.0 ± 1.3°. The results demonstrate that electrospraying is a simple, innovative and cost-effective method for preparing polymer microspheres with controllable microstructures for fabric coating applications.

Challenges for the development of surface modified biodegradable polyester biomaterials: A chemistry perspective

The design of current implants produced from biodegradable polyesters is based on strength and rate of degradation and tailored by the choice of polyester used. However, detailed knowledge about the degradation mechanism of surface modified materials with applications in biomaterials science and tissue engineering is currently lacking. This perspective aims to outline the need for a greater focus on analyzing the degradation of modified polyesters to ensure they can fulfil their intended function and that degradation products can effectively be cleared from the body. The status of the literature regarding surface modified polyesters is summarized to illustrate the main aspects investigated in recent studies and specifically the number of studies investigating the fate of the materials upon degradation.