Novel Biopolymer Structures Synthesized by Dendronization of 6-Deoxy-6-aminopropargyl cellulose

Screening of chemical linkers for development of pullulan bioconjugates for intravitreal ocular applications

The treatment of posterior segment disorders of the eye requires therapeutic strategies to achieve drug effects over prolonged times. Innovative colloidal delivery systems can be designed to deliver drugs to the retina and prolong their intravitreal permanence. In order to exploit pullulan (Pull) as polymeric drug carrier for intravitreal drug delivery, derivatives of hydrophobic model molecule rhodamine B (RhB) were conjugated to the pullulan backbone through linkers with different stability, namely ether (Et), hydrazone (Hy) or ester (Es) bond to obtain Pull-Et-RhB, Pull-Hy-RhB and Pull-Es-RhB, respectively. Dynamic light scattering and transmission electron microscopy analyses showed that the polymer conjugates self-assembled into 20-25 nm particles. Pull-Et-RhB was fairly stable at all tested pH values. At the vitreal pH of 7.4, 50% of RhB was released from Pull-Hy-RhB and Pull-Es-RhB in 11 and 6 days, respectively. At endosomal pH (5.5), 50% of RhB was released from Pull-Hy-RhB and Pull-Es-RhB in 4 and 1 days, respectively. Multiple particle tracking analyses in ex vivo porcine eye model showed that the diffusivity of the bioconjugates in the vitreous was about 10³ times lower than in water. Flow cytometry and confocal microscopy analyses showed that bioconjugates are remarkably taken up by the retinal RPE cells. In vivo studies showed that after intravitreal injection to mice, the bioconjugates localize in the ganglion cell layer and in the inner and outer plexiform layers. Pull-Hy-RhB particles were detected also inside the retinal blood vessels. These results demonstrate that pullulan with tailored linkers for drug conjugation is a promising vehicle for long-acting intravitreal injectables that are capable to permeate to the retina.

Green Fabrication of Highly Conductive Paper Electrodes via Interface Engineering with Aminocellulose

Herein, a novel, facile, and versatile approach to fabricate highly flexible and conductive paper is proposed by electroless deposition (ELD) with the assistance of aminocellulose as the interface layer. The obtained Cu nanoparticles (NPs)-coated cellulose paper is highly conductive with a significant low resistance of 0.38 Ω sq^-1 after only 10 min of ELD treatment. This conductive cellulose paper shows excellent stability when it suffers from bending, folding, and tape adhesion cycles. With the same method, the Cu NPs can also be successfully deposited on the polypropylene (PP)-filled hybrid paper. The conductive paper exhibits very smooth and hydrophobic surface with high reflection, which can be used for special electronic devices. In a word, the fabrication of aminocellulose interface permits a controlled ELD of metal nanoparticles on paper substrate, and this mild and low-cost method opens up new opportunities for large-scale production of flexible and wearable electronics.

Synthesis of allyl cellulose in NaOH/urea aqueous solutions and its thiol–ene click reactions

Allyl cellulose can be synthesized from cellulose and allyl chloride in NaOH/urea aqueous solutions and is further used to synthesize a variety of new cellulose derivatives through the thiol–ene click reaction.

Regioselective esterification and etherification of cellulose: a review

Deep understanding of the structure-property relationships of polysaccharide derivatives depends on the ability to control the position of the substituents around the monosaccharide ring and along the chain. Equally important is the ability to analyze position of substitution. Historically, both synthetic control and analysis of regiochemistry have been very difficult for cellulose derivatives, as for most other polysaccharide derivatives. With the advent of cellulose solvents that are suitable for chemical transformations, it has become possible to carry out cellulose derivatization under conditions sufficiently mild to permit increasingly complete regiochemical control, particularly with regard to the position of the substituents around the anhydroglucose ring. In addition, new techniques for forming cellulose and its derivatives from monomers, either by enzyme-catalyzed processes or chemical polymerization, permit us to address new frontiers in regiochemical control. We review these exciting developments in regiocontrolled synthesis of cellulose derivatives and their implications for in-depth structure-property studies.