A comprehensive review of biodegradable synthetic polymer-ceramic composites and their manufacture for biomedical applications

Abstract

The application of various materials in biomedical procedures has recently experienced rapid growth. One area that is currently receiving significant attention from the scientific community is the treatment of a number of different types of bone-related diseases and disorders by using biodegradable polymer-ceramic composites. Biomaterials, the most common materials used to repair or replace damaged parts of the human body, can be categorized into three major groups: metals, ceramics, and polymers. Composites can be manufactured by combining two or more materials to achieve enhanced biocompatibility and biomechanical properties for specific applications. Biomaterials must display suitable properties for their applications, about strength, durability, and biological influence. Metals and their alloys such as titanium, stainless steel, and cobalt-based alloys have been widely investigated for implant-device applications because of their excellent mechanical properties. However, these materials may also manifest biological issues such as toxicity, poor tissue adhesion and stress shielding effect due to their high elastic modulus. To mitigate these issues, hydroxyapatite (HA) coatings have been used on metals because their chemical composition is similar to that of bone and teeth. Recently, a wide range of synthetic polymers such as poly (l-lactic acid) and poly (l-lactide-co-glycolide) have been studied for different biomedical applications, owing to their promising biocompatibility and biodegradability. This article gives an overview of synthetic polymer-ceramic composites with a particular emphasis on calcium phosphate group and their potential applications in tissue engineering. It is hoped that synthetic polymer-ceramic composites such as PLLA/HA and PCL/HA will provide advantages such as eliminating the stress shielding effect and the consequent need for revision surgery.

Keywords: 3D printing; Hydroxyapatite; Magnetron sputtering; Synthetic polymers.

Graphical abstract

Fig. 1

Calcium phosphate-based biomaterials for bone graft applications (Adopted from Ref. [13]).

Fig. 2

SEM micrographs of HA particles with different sizes and shapes: a) microscale, b) plate, c) spherical, d) nanoscale (Adapted from Ref. [27]).

Fig. 3

Porous β-TCP with different pore sizes: (a) 100–200 μm, (b) 300–400 μm, (c) 500–600 μm, and (d) 700–800 μm (Adopted from Ref. [13]).

Fig. 4

Three main categories of polyesters (Adapted from Ref. [65]).

Fig. 5

Chemical structure of PLGA and its monomers (n and m demonstrate the number of repetition of each unit).

Fig. 6

(a) Screws and plate made of PLA, (b) upper jaw with the plates and screws in situ, (c) and (d) lateral cephalogram, with the screws and plate, taken immediately postoperatively and six weeks postoperatively, respectively. (Adapted from Refs. [96,97]).

Fig. 7

SEM images of: (a) neat PLGA (top view), (b) neat PLGA (front view), (c) PLGA/HA composites (top view), and (d) PLGA/HA composites (front view) manufactured by SLS (Adapted from Ref. [107]).

Fig. 8

The stress-strain behaviour for pure PLLA and gHA-PLLA composite (Adapted from Ref. [114]).

Fig. 9

PLA scaffolds manufactured by FDM (Adapted from Ref. [123]).

Fig. 10

a) Extrusion process of PLA/HA composites, and b) PLA and PLA/HA filament (white one) (Adopted from Ref. [131]).

Fig. 11

Diagrams of: (a) SLA, (b) FDM, (c) SLS, (d) inkjet bioprinting and their models (Adapted from Refs. [[132], [133], [134], [135], [136], [137], [138], [139]]).

Fig. 12

Schematic of a sputtering technique.

Fig. 13

Schematic of the sol-gel technology (Adapted from Ref. [166]).