Gancheng Zuo

Salecan-Based pH-Sensitive Hydrogels for Insulin Delivery

Stimuli-responsive polymeric hydrogels are promising and appealing delivery vehicles for protein/peptide drugs and have made protein/peptide delivery with both dosage- and spatiotemporal-controlled manners possible. Here a series of new Salecan-based pH-sensitive hydrogels were fabricated for controlled insulin delivery via the graft copolymerization reaction between Salecan and 2-acrylamido-2-methyl-1-propanesulfonic acid. In this study, on one hand, Salecan played a key role in modifying the structure and the pore size of the developing hydrogel. On the other hand, Salecan tuned the water content and the water release rate of the obtained hydrogel, leading to a controllable release rate of the insulin. More importantly, in vitro release experiments validated that the release of insulin from this intelligent system could be also tailored by the environmental pH of the release medium. For SGA2, the amount of encapsulated insulin released at gastric conditions (pH 1.2) was relatively low (about 26.1 wt % in 24 h), while that released at intestinal conditions (pH 7.4) increased significantly (over 50 wt % in 6 h). Furthermore, toxicity assays demonstrated that the designed hydrogel carriers were biocompatible. These characteristics make the Salecan-based hydrogel a promising candidate for protein/peptide drug delivery device.

Development of novel hydrogels based on Salecan and poly(N-isopropylacrylamide-co-methacrylic acid) for controlled doxorubicin release

Salecan is a novel water-soluble extracellular polysaccharide composed of a linear repeating unit of 1-3-linked glucopyranosyl. Salecan is suitable for the preparation of hydrogels for biomedical applications due to its outstanding biological and physicochemical profiles. Here we designed a novel semi-interpenetrating polymer network (semi-IPN) hydrogel that incorporated the hydrophilic polysaccharide Salecan into a stimuli-responsive poly(N-isopropylacrylamide-co-methacrylic acid) (PNM) hydrogel matrix for controlled drug release. In this research, on one hand, Salecan modified the architecture and the pore size of the semi-IPN network. On the other hand, Salecan played a vital role in modulating water content and tuning the water release rate of the developing hydrogel, resulting in an adjustable release rate of the drugs. Doxorubicin (DOX), an anticancer drug, was loaded into the semi-IPN hydrogels as a model drug, and the in vitro release assay exhibited that the release rate was closely related to the content of introduced Salecan, as well as the environmental temperature and pH of the release media. Cytotoxicity experiments demonstrated that all blank semi-IPN hydrogels were non-toxic to HepG2 and A549 cells, while drug released from the DOX-loaded hydrogels could still exert its pharmacological activity and had the ability to kill these two cancer cells. Altogether, this work provides a way to synthesize a new type of hydrogel as general drug delivery vectors with a desired release rate.

Synthesis and Characterization of a Multi-Sensitive Polysaccharide Hydrogel for Drug Delivery

Salecan is a novel water soluble polysaccharide produced by a salt-tolerant strain Agrobacterium sp. ZX09. Poly(dimethylaminoethyl methacrylate) (PDMAEMA) is a pH, thermo, and ionic strength multi-sensitive polymer with anti-bacterial property. Here, we report a semi-interpenetrating polymer network (semi-IPN) hydrogel based on salecan and PDMAEMA. The obtained hydrogel is simultaneous sensitive to pH, ionic strength and temperature: the swelling ratio maximizes at pH 1.2 and shrinks at pH value greater than 3; besides, water content of the hydrogel decreases as the ionic strength increases; in terms of temperature, the hydrogel swells/deswells at temperatures below/above 40°C. Cytotoxicity test shows the hydrogel is non-cytotoxic to COS-7 cells. Protein drug insulin was selected as model drug to test the in vitro release behavior of the hydrogel. Results show the release rate increases with the swelling ratio of the hydrogel. In addition, when the temperature is higher than the lower critical solution temperature (LCST) of PDMAEMA, the hydrogel shrinks to extrude more drug molecules. Moreover, the release rate and release amount were higher in acid condition (pH 1.2) than at pH 7.4. In summary, this polysaccharide hydrogel is a promising material for drug delivery.

Design of Salecan-containing semi-IPN hydrogel for amoxicillin delivery

Salecan is a new linear extracellular β-glucan. The unique structure and beneficial properties of Salecan makes it an appealing material in biomedical applications. In this work, novel drug devices based on Salecan in a hydrogel matrix of poly(N-(3-dimethylaminopropyl)acrylamide-co-acrylamide) (Salecan/PDA) were fabricated via free radical polymerization for controlled release of amoxicillin. It was demonstrated that amoxicillin was efficiently encapsulated into the developed hydrogels and released in a Salecan dose-dependent and pH-sensitive manner. Furthermore, cell toxicity and adhesion assays confirmed that these drug carriers were biocompatible. Altogether, this study opens a new avenue to fabricate hydrogel devices for controlled delivery of drug.

Cationic Salecan-based hydrogels for release of 5-fluorouracil

Salecan, a new water-soluble β-glucan, has excellent physicochemical and biological characteristics. Here, a series of pH-sensitive hydrogels based on Salecan grafted with [2-(methacryloxy)ethyl]trimethylammonium chloride were developed for controlled drug delivery. The successful preparation of the grafted hydrogels was confirmed by Fourier transform infrared spectroscopy, X-ray diffraction, and thermogravimetric analysis. After that, rheology and scanning electron microscopy tests showed that the mechanical and morphological properties of these hydrogels were strongly influenced by the Salecan content. Moreover, the swelling behavior of the resulting hydrogels was systematically studied, and the results suggested that they exhibited pH sensitivity. Loading and delivery experiments demonstrated that 5-fluorouracil was efficiently encapsulated into the hydrogel matrices and released in a predictable manner via pH and Salecan dose control. Finally, cell viability and adhesion assays verified the cell compatibility of the designed hydrogels. Altogether, these attributes make the Salecan-based graft hydrogel a promising platform for controlled 5-fluorouracil delivery.

Selective determination of Ag+ using Salecan derived nitrogen doped carbon dots as a fluorescent probe

We report that nitrogen doped carbon dots (N-CDs) represent a viable fluorescent probe for the determination of Ag+. The N-CDs can be fairly easily prepared by a hydrothermal treatment method using Salecan and dicyandiamide as the precursors, display excitation/emission maxima of 350/438nm. The N-CDs have an average diameter of about 3.8nm. The N-CDs exhibited blue fluorescence (quantum yield of 13.2%) and could response to Ag+ selectively and sensitively. Other ions nearly had no interference. The probe has excellent selectivity, high sensitivity, and a linear response range that extends from 0 to 40μM. The limit of detection is as low as 1.12×10-7mol/L. The method was applied to the determination of Ag+ dissolved in water.

Preparation of a Salecan/poly(2-acrylamido-2-methylpropanosulfonic acid-co-[2-(methacryloxy)ethyl]trimethylammonium chloride) Semi-IPN Hydrogel for Drug Delivery.

Salecan is a water‐soluble bacterial polysaccharide consisting of glucopyranosyl units linked by α‐1,3 and β‐1,3 glycosidic bonds. salecan is suitable for the development of hydrogels for biomedical applications, given its outstanding physicochemical and biological profiles. In this study we designed a new semi‐interpenetrating polymer network hydrogel that introduces the salecan polysaccharide into a stimuli‐responsive poly(2‐acrylamido‐2‐methylpropanosulfonic acid‐co‐[2‐(methacryloxy)ethyl]trimethylammonium chloride) (PAM) hydrogel matrix for controlled insulin release. We found that salecan not only tunes the structure and pore size of the PAM hydrogels, but also endows them with adjustable water release rates. More importantly, in vitro drug loading/release assays demonstrated that insulin is efficiently loaded into the resulting hydrogels and can be released in an on‐demand manner by controlling the pH and salecan dose. Furthermore, cell viability and cell adhesion experiments verified the cell compatibility of these hydrogel carriers. Together, these results make salecan‐incorporated PAM hydrogels promising materials for drug delivery.

Synthesis and characterization of a novel cationic hydrogel base on salecan-g-PMAPTAC

Salecan is a biological macromolecular and biocompatible polysaccharide that has been investigated for recent years. Herein, we report a novel cationic hydrogel fabricated by graft-polymerizing 3-(methacryloylamino)propyl-trimethylammonium chloride (MAPTAC) onto salecan chains. The obtained hydrogels were transparent, solid-elastic, macro-porous, ion-sensitive, and non-cytotoxic. The swelling ratios increased with salecan content, while mechanical strength does the opposite. Moreover, drug delivery test was studied as a potential application. Diclofenac sodium (DS) and insulin were selected as model drugs. Interestingly, in drug loading process, DS molecules exhibited highly affinity to these cationic hydrogels. Almost all the DS molecules in loading solution were absorbed and spread into the hydrogel. For drug release profiles, insulin-loaded hydrogel showed an initial rapid release and a sustained release. As a comparison, DS-loaded hydrogel exhibited a more sustained release profile. Results suggested salecan-g-PMAPTAC hydrogel could be a good candidate for anionic drug loading and delivery.

Polysaccharide metallohydrogel obtained from Salecan and trivalent chromium: Synthesis and characterization

Here, a new kind of Salecan derived polysaccharide metallohydrogel was reported. Successful fabrication of Salecan metallohydrogel was verified by Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, and rheological measurements. Scanning electron microscope investigations have been conducted to elucidate the morphology of Salecan/Cr3+ gel (SCgel). We found that the pore size of metallohydrogel can be tailored by adjusting the Cr3+ dose during gel formation. After that, swelling and de-swelling behaviors were systematically studied. The increasing of chromium ion concentration and the presence of saline solutions will cause the decrease of swelling percentage. It is assumed that the decreasing hydrophilicity of Salecan, the increase of crosslinking density, and the complexation of the carboxylate group with saline ions are the main syneresis mechanisms. Altogether, this study opens a new avenue to prapare Salecan-based hydrogel.