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Summary: Three different cellulosic substrata, like microcrystalline cellulose, cotton cellulose and spruce dissolving pulp, were chosen for biodegradation. The kinetics of the enzymatic hydrolysis of these celluloses by Trichoderma reesei, has been investigated. The experiments proved the fact that both the morphological structure and the crystalline one are crucial to the process and the ratio of the reactions. In addition, in order to obtain the most accessible cellulose substratum it was studied the biodegradation of cellulose allomorphs of spruce dissolving pulp. The insoluble cellulose fraction remaining after enzymatic hydrolysis was examined by X‐ray diffraction method and it was established the degree of crystallinity and the average crystallite size. The enzymatic degradation is also proved by the decrease in the degree of polymerization of hydrolyzed samples.

Hydrogels, three-dimensional (3D) polymer networks, present unique properties, like biocompatibility, biodegradability, tunable mechanical properties, sensitivity to various stimuli, the capacity to encapsulate different therapeutic agents, and the ability of controlled release of the drugs. All these characteristics make hydrogels important candidates for diverse biomedical applications, one of them being drug delivery. The recent achievements of hydrogels as safe transport systems, with desired therapeutic effects and with minimum side effects, brought outstanding improvements in this area. Moreover, results from the utilization of hydrogels as target therapy strategies obtained in clinical trials are very encouraging for future applications. In this regard, the review summarizes the general concepts related to the types of hydrogel delivery systems, their properties, the main release mechanisms, and the administration pathways at different levels (oral, dermal, ocular, nasal, gastrointestinal tract, vaginal, and cancer therapy). After a general presentation, the review is focused on recent advances in the design, preparation and applications of innovative cellulose-based hydrogels in controlled drug delivery.

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The supramolecular architecture and the morphological structure of cellulose play an important role in its accessibility. In order to evaluate the effect of the crystalline form of organization on the accessibility, we selected cellulosic materials with significant variations in the aforementioned characteristics. The assessment of the accessibility of cellulosic materials was performed experimentally through a water vapor sorption method. The kinetics and the thermodynamic parameters of water vapor sorption process were determined, and a correlation between the Flory-Huggins interaction parameters and the crystallinity index was derived. We concluded that the allomorph involving the most accessible crystal surfaces and amorphous regions was Cellulose II. The correlation of the accessibility values with those of the crystallinity index allowed us to evaluate the accessibility of the allomorphic forms of cellulose at different crystallinity indexes. The obtained experimental data allowed us to quantify the accessibility for crystal surfaces and amorphous regions of the different allomorphs in the order Cellulose II (38%) [ Cellulose I (24%) [ Cellulose III (10%).