**5. Conclusions**

Although research in this area has revolutionized the biomedical and pharmaceutical industries, significant work still lies ahead if we are to effect changes not only at the individual level but also to bring sustained and affordable environmental changes. Biopolymers have proven effective as encapsulation materials for controlled drug release systems. Significant progress has been made on the biocompatibility, biodegradability, and mechanical and thermal properties of the materials involved. However, challenges still remain in developing target-specific carriers that are biocompatible with various delivery routes for providing sustainable release at the target site. Strategies have been proposed to improve stability of polymers, product kinetics, and release time as well as clinical efficiency. For biomedical applications, it is important to develop uniform guidelines for polymer applications in order to improve versatility and safety and avoid contamination. From the evidence presented thus far, it is obvious that among biopolymers, polysaccharides-based applications are the most used in the field due to their protective, physicochemical, and low immunogenicity characteristics. Although they present some limitations, the ability to react synergistically with other biopolymers or other natural or synthetic substances make their applications widely used. More studies evaluating the technical parameter optimization, efficiency of encapsulation with different formulations, and product-loading capacity concerning viability and metabolic activity should be undertaken. For example, studies examining the functional interactions between the polymer networks and the coating materials, in order to improve capsule stability, product metabolic activity, release time, and viability, should be high on the list. Notwithstanding current limitations from the host perspective, the use of polymers, particularly polysaccharides-based, will continue to expand with an eye towards improving polysaccharide-drug interactions, the optimization of pharmacokinetics and pharmacodynamics, and the compatibility of the polysaccharide with the target tissue. Nevertheless, while more research is needed, polymer-based applications are of great benefit for delivering small molecules that are highly effective, biopotent, and safe.

**Author Contributions:** All authors have contributed equally to this work. All authors have read and agreed to the published version of the manuscript.

**Funding:** The work was supported by the project titled "The analysis of interrelationship between gut microbiota and the host with applications in the prevention and control of type 2 diabetes", co-financed by the European Regional Development Fund through Competitiveness Operational Program under the contract number 120/16.09.2016.

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** The data presented in this study are available upon request from the corresponding author.

**Conflicts of Interest:** The authors declare no conflict of interest.
