Multiscale requirements for bioencapsulation in medicine and biotechnology

Bioencapsulation involves the envelopment of tissues or biological active substances in semipermeable membranes. Bioencapsulation has been shown to be efficacious in mimicking the cell's natural environment and thereby improves the efficiency of production of different metabolites and therapeutic agents. The field of application is broad. It is being applied in bioindustry and biomedicine. It is clinically applied for the treatment of a wide variety of endocrine diseases. During the past decades many procedures to fabricate capsules have been described. Unfortunately, most of these procedures lack an adequate documentation of the characterization of the biocapsules. As a result many procedures show an extreme lab-to-lab variation and many results cannot be adequately reproduced. The characterization of capsules can no longer be neglected, especially since new clinical trials with bioencapsulated therapeutic cells have been initiated and the industrial application of bioencapsulation is growing. In the present review we discuss novel Approached to produce and characterize biocapsules in view of clinical and industrial application. A dominant factor in bioencapsulation is selection and characterization of suitable polymers. We present the adequacy of using high-resolution NMR for characterizing polymers. These polymers are applied for producing semipermeable membranes. We present the pitfalls of the currently applied methods and provide recommendations for standardization to avoid lab-to-lab variations. Also, we compare and present methodologies to produce biocompatible biocapsules for specific fields of applications and we demonstrate how physico-chemical technologies such as FT-IR, XPS, and TOF-SIMS contribute to reproducibility and standardization of the bioencapsulation process. During recent years it has become more and more clear that bioencapsulation requires a multidisciplinary approach in which biomedical, physical, and chemical technologies are combined. For adequate reproducibility and for understanding variations in outcome of biocapsules it is advisable if not mandatory to include the characterization processes presented in this review in future studies.