During the resorbable-polymer-boom of the 1970s and 1980s, polycaprolactone (PCL) was used in the biomaterials field and a number of drug-delivery devices. Its popularity was soon superseded by faster resorbable polymers which had fewer perceived disadvantages associated with long term degradation (up to 3-4 years) and intracellular resorption pathways; consequently, PCL was almost forgotten for most of two decades. Recently, a resurgence of interest has propelled PCL back into the biomaterials-arena. The superior rheological and viscoelastic properties over many of its aliphatic polyester counterparts renders PCL easy to manufacture and manipulate into a large range of implants and devices. Coupled with relatively inexpensive production routes and FDA approval, this provides a promising platform for the production of longer-term degradable implants which may be manipulated physically, chemically and biologically to possess tailorable degradation kinetics to suit a specific anatomical site. This review will discuss the application of PCL as a biomaterial over the last two decades focusing on the advantages which have propagated its return into the spotlight with a particular focus on medical devices, drug delivery and tissue engineering.

The return of a forgotten polymer : Polycaprolactone in the 21st century

Bio-based electrospun nanofiber as building blocks for a novel eco-friendly air filtration membrane: A review

Recent advances in polysaccharide-based self-healing hydrogels for biomedical applications.

Self-healing polysaccharide-based injectable hydrogels with antibacterial activity for wound healing

Self-healing polysaccharide-based injectable hydrogels with antibacterial activity for wound healing.

Recent Advances in Design of Functional Biocompatible Hydrogels for Bone Tissue Engineering

Fabrication of physical and chemical crosslinked hydrogels for bone tissue engineering

Osteoarthritis (OA), as a chronic degenerative joint disorder, has seriously affected the life quality of patients. Despite lots of drug treatment strategies that have been studied, the therapeutic effect is still unsatisfactory due to the lack of prolonged circulation life and targeted delivery ability. Recently, functional cell membranes modified nanoparticles have been explored to achieve high-efficiency drug delivery. Herein, neutrophil-erythrocyte hybrid membranes-coated dexamethasone sodium phosphate (Dexp)-loaded hollow copper sulfide nanoparticles (D-CuS@NR NPs) were fabricated for OA treatment. Generally, we achieved the synergistic treatment of mild-heating, prolonged circulation, and targeted delivery in this system. In particular, this biomimetic nanoparticle showed significant cytocompatibility and anti-inflammatory ability in vitro due to cell membrane coating and photothermal responsive drug release under NIR irradiation. Importantly, in vivo explorations revealed that D-CuS@NR NPs combined with photothermal treatment obtained an excellent therapy effect for preventing the OA process. Hence, this novel hybrid membranes-coated CuS NPs showed significant therapeutic efficacy by local warming and targeted drug delivery , which might become a promising drug delivery vehicle for improving the therapeutic effect of OA. • This nanoparticle possesses lots of advantages, including long circulation effect, excellent target ability, and well photothermal conversion efficiency. • Combined with NIR treatment, this drug loaded nanoparticle gained outstanding anti-inflammatory effect and ability to protect articular cartilage in vivo . • This drug loaded nanoparticle provides a promising platform for inflammation related diseases. 

Neutrophil-erythrocyte hybrid membrane-coated hollow copper sulfide nanoparticles for targeted and photothermal/ anti-inflammatory therapy of osteoarthritis

3D‐printed polycaprolactone (PCL) scaffolds have been extensively studied for application in bone tissue engineering. However, PCL‐based scaffolds with enhanced bioactivity and intelligent delivery capability for bone repair remains challenging. Herein, CuS nanoparticle‐PEG soft hydrogel‐coated 3D hard polycaprolactone scaffolds (denoted as CuS‐PEG‐PCL scaffold) are rationally designed for efficient bone regeneration. CuS nanoparticles cross‐linked PEG hydrogel (CuS‐PEG‐hydrogel) endows the PCL‐based scaffold with excellent photothermal properties and stable soft elasticity, while the PCL scaffold provides excellent mechanical performance. Upon exposure to 1064 nm near‐infrared (NIR) light irradiation, dexamethasone sodium phosphate (Dexp), stored in the CuS‐PEG‐PCL scaffold, can be controllably released, which efficiently promotes osteogenic differentiation of bone mesenchymal stem cells (BMSCs). In addition, the combination of mild heating at 42 ± 0.5 °C further promoted osteogenic differentiation of BMSCs. Subsequently, this Dexp‐loaded CuS‐PEG‐PCL scaffold (D‐CuS‐PEG‐PCL scaffold) with NIR light treatment at the tibial defect of rats presented the highest bone regeneration capacity. These findings demonstrate that the Dexp‐loaded CuS‐PEG‐hydrogel can effectively modify the 3D printed PCL scaffold. Therefore, this multifunctional scaffold with a soft‐hard hybrid structure has the potential to become an advanced drug delivery vehicle in the treatment of large bone defects.

Rational Design of Multifunctional CuS Nanoparticle‐PEG Composite Soft Hydrogel‐Coated 3D Hard Polycaprolactone Scaffolds for Efficient Bone Regeneration

Xu Xue

Papers

Recent Advances in Design of Functional Biocompatible Hydrogels for Bone Tissue Engineering

Fabrication of physical and chemical crosslinked hydrogels for bone tissue engineering

Neutrophil-erythrocyte hybrid membrane-coated hollow copper sulfide nanoparticles for targeted and photothermal/ anti-inflammatory therapy of osteoarthritis

Rational Design of Multifunctional CuS Nanoparticle‐PEG Composite Soft Hydrogel‐Coated 3D Hard Polycaprolactone Scaffolds for Efficient Bone Regeneration

Engineered extracellular vesicles for bone therapy