Table 1.
Natural and Synthetic Polymers for Controlled Delivery of Therapeutics
| Polymer | Synthetic/Natural | FDA approved | Biodegradability Biocompatible | Stimuli responsive | Sterilization | Challenges |
|---|---|---|---|---|---|---|
| Albumin44 | Natural | Yes | Yes/Yes | Thermoresponsive | -Sterile filtration | Various side effects (allergic reactions, immunological response) |
| Alginate 45 | Natural | Yes | Yes/Yes | Thermoresponsive pH responsive |
-Sterile filtration -Heat treatment |
Limited long-term stability in physiological conditions |
| Chitosan 46 | Natural | No | Yes/Yes | Thermoresponsive pH responsive |
-Ozonation -Ultraviolet |
Poor solubility at physiological pH Batch to batch variation |
| Collagen 42 | Natural | Yes | Yes/Yes | No | - Chloroform - Ethylene oxide - Gamma rad. |
Poor mechanical strength |
| Dextrins 47 | Natural | Yes | Yes/Yes | No | - Ethylene oxide - Gamma rad. |
Microbial contamination, Uncontrolled rates of hydration Decrease in viscosity during storage |
| Gelatin 48, 49 | Natural | Yes | Yes/Yes | Thermoresponsive pH responsive |
-Steam heat -Sterile filtration - Gamma rad. |
Poor mechanical properties |
| HA 50 | Natural | Yes | Yes/Yes | No | -Heat treatment -Sterile filtration |
Accumulation in liver Low accumulation in tumor sites |
| HPMA 51 | Synthetic | Yes | No/Yes | No | -Heat treatment | Non biodegradable Elimination via kidney |
| PCL 52 | Synthetic | Yes | Yes/Yes | No | -Ultraviolet | Low melting point |
| PEG 51, 53 | Synthetic | Yes | No/Yes | Thermoresponsive | -Sterile filtration | Accumulation in the body Low peptide/protein conjugation |
| PEI 54 | Synthetic | No | No/No | No | -Ethylene oxide -Gamma rad. -Steam heat |
Cytotoxicity |
| PLGA 4, 41 | Synthetic | Yes | Yes/Yes | No | - Plasma - Ethylene oxide - Gamma rad. |
Low solubility High rate of degradation Acidic degradation products Challenge of biosynthesis Protein aggregation and instability Burst release of large molecules |
|
Silk Fibroin
Silk Sericin 19, 43 |
Natural | Yes | Yes/Yes | pH responsive Thermoresponsive Enzyme activity Physical stimuli |
-Steam heat -Sterile filtration -Gamma rad. |
Batch to batch variation |
*
HA: Hyaluronic acid, HPMA: [N-(2- hydroxypropyl)methacrylamide], PEG: polyethylene glycol, PEI: Polyethylenimine, PLGA: poly lactic-co-glycolic acid, PCL: Polycaprolactone