Table 3.
Comparison of synthetic and natural polyesters production, processing, properties and application.
| Synthetic polyesters | Bacterial polyesters (PHA) | Ref. | |
|---|---|---|---|
| Production and processing | Bio-production of LA and chemical synthesis of PLA, PLGA | Completely biosynthesized | 4, 96, 131 |
| No possibility of in vivo production and functionalization | In vivo functionalization; One-step production of active agent and carrier, no need to produce, purify and conjugate active agent | 26, 54, 131 | |
| Use of harsh chemicals for production | Production from renewable sources | 4, 132 | |
| Difficulty to scale-up | Similar to bioprocesses for PHA production; Certain difficulties to scale-up | 132, 133 | |
| Production cost comparable with conventional plastics like PET | High cost of production; at least twice that of PLA | 4, 131 | |
| High risk due to flammable and toxic solvents | Low risk level | 132 | |
| Production completed within days | Production duration 1-2 weeks | 132 | |
| Endotoxin contamination less probable due to synthetic origin | Endotoxins can be efficiently removed; Use of Gram+ strains allows endotoxin free production | 20 | |
| Properties | Lower number of copolymers that can be produced; Only d- and l-lactic acids (LA) | More than 150 monomeric building blocks for polymer design | 4, 131 |
| Approved by FDA and European Medicine Agency as drug delivery system | Not approved by FDA as drug delivery system | 131, 133, 3 | |
| Low drug loading | No limitations regarding drug loading | 32, 131, 133 | |
| Protection of drug from degradation | Protection of drug from degradation | 133, 3, 134 | |
| Biodegradable, biocompatible, low cytotoxicity | Biodegradable, biocompatible, low cytotoxicity | 30, 32, 96, 3 | |
| Material properties poor, could be adjusted by regulating d- and l-LA ratios | Good thermomechanical properties from brittle, flexible to elastic, fully controllable, easy processability | 4, 30, 96, 135 | |
| Degradation rate can be controlled | Degradation rate can be controlled | 130, 3 | |
| Drug delivery kinetics can be controlled | Drug delivery kinetics can be controlled | 32, 130 | |
| Easy particle size control | Size of in vitro produced particles might be controlled, in vivo production limits control over particle size | 30, 32, 34, 134 | |
| Application | Wind variety of biomedical applications | Applicable to a range of diseases | 26, 133 |
| Lowering pH at the site of implantation that might lead to sterile sepsis | No detected side effect of PHA degradation | 130, 131 | |
| Best chance for clinical application due to FDA approval. Packaging, printing, coating, yet limited by Tg of 65-75 °C | Almost all areas of conventional plastic industry, limited by current higher cost and availability | 4, 20, 131, 134 |