Thermoresponsive hydroxybutylated starch nanoparticles

Highly branched thermoresponsive polysaccharide derivative in water. Partly substituted highly branched cyclic dextrin ethylcarbamate

A thermoresponsive highly branched polysaccharide derivative was revealed from commercially available highly branched cyclic dextrin (HBCD), originally synthesized from amylopectin. Eight samples of partially substituted ethyl carbamate derivatives of HBCD (HEC) were prepared with a degree of substitution DS ranging from 0.27 to 1.46. Three samples with DS = 0.88, 1.05, and 1.22 showed LCST type phase separation in water. The intrinsic viscosity and form factor in water were typical of the hyperbranched structure. The intermolecular interactions between HEC and iodine or 1-anilinonaphthalene-8-sulfonic acid (ANS) were appreciably different from those of the linear analog (AEC), suggesting that the locally bent helical conformation of highly branched HEC chains has a different interaction with small molecules. The phase diagram of HEC-water systems was accidentally similar to that of the linear chain with the same molar mass and DS, although the one phase region of the branched polymer chain-poor solvent system is usually wider than that of the corresponding linear chain. This is likely due to the lower hydration nature of the polymer segment of HEC chains than that of the corresponding linear chain.

A smart thermoresponsive macroporous 4D structure by 4D printing of Pickering-high internal phase emulsions stabilized by plasma-functionalized starch nanomaterials for a possible delivery system

Hierarchically porous structures combine microporosity, mesoporosity, and microporosity to enhance pore accessibility and transport, which are crucial to develop high performance materials for biofabrication, food, and pharmaceutical applications. This work aimed to develop a 4D-printed smart hierarchical macroporous structure through 3D printing of Pickering-type high internal phase emulsions (Pickering-HIPEs). The key was the utilization of surface-active (hydroxybutylated) starch nanomaterials, including starch nanocrystals (SNCs) (from waxy maize starch through acid hydrolysis) or starch nanoparticles (SNPs) (obtained through an ultrasound treatment). An innovative procedure to fabricate the functionalized starch nanomaterials was accomplished by grafting 1,2-butene oxide using a cold plasma technique to enhance their surface hydrophobicity, improving their aggregation, and thus attaining a colloidally stabilized Pickering-HIPEs with a low concentration of each surface-active starch nanomaterial. A flocculation of droplets in Pickering-HIPEs was developed after the addition of modified SNCs or SNPs, leading to the formation of a gel-like structure. The 3D printing of these Pickering-HIPEs developed a highly interconnected large pore structure, possessing a self-assembly property with thermoresponsive behavior. As a potential drug delivery system, this thermoresponsive macroporous 3D structure offered a lower critical solution temperature (LCST)-type phase transition at body temperature, which can be used in the field of smart releasing of bioactive compounds.

Synthesis, characteristics, and applications of modified starch nanoparticles: A review

Nowadays, starch nanoparticles (SNPs) are drawing attention to the scientific community due to their versatility and wide range of applications. Although several works have extensively addressed the SNP production routes, not much is discussed about the SNPs modification techniques, as well as the use of modified SNPs in typical and unconventional applications. Here, we focused on the SNP modification strategies and characteristics and performance of the resulting products, as well as their practical applications, while pointing out the main limitations and recommendations. We aim to guide researchers by identifying the next steps in this emerging line of research. SNPs esterification and oxidation are preferred chemical modifications, which result in changes in the functional groups. Moreover, additional polymers are incorporated into the SNP surface through copolymer grafting. Physical modification of starch has demonstrated similar changes in the functional groups without the need for toxic chemicals. Modified SNPs rendered differentiated properties, such as size, shape, crystallinity, hydrophobicity, and Zeta-potential. For multiple applications, tailoring the aforementioned properties is key to the performance of nanoparticle-based systems. However, the number of studies focusing on emerging applications is fairly limited, while their applications as drug delivery systems lack in vivo studies. The main challenges and prospects were discussed.

[Development of an asymmetrical flow field-flow fractionation system for the size characterization of starch granules]

淀粉颗粒粒径与分子尺寸分别在1~100 μm和20~250 nm之间,是影响淀粉功能特性的重要因素之一。非对称场流分离(AF4)是一种基于样品与外力场相互作用机制的分离技术,已应用于表征淀粉分子尺寸分布。商品化的AF4系统的粒径检测范围为1 nm~10 μm,对于淀粉颗粒粒径表征具有一定的局限性。该文研制了AF4分离系统;考察了其在微米尺度下对红薯、莲子和大米淀粉颗粒粒径表征的性能;采用微米尺寸的聚苯乙烯乳化球(PS)标准样品验证了构建的AF4系统的分离性能。实验结果显示,构建的AF4系统对PS混合样品(粒径2、6、12、20 μm)实现了基线分离,同商品化AF4相比提高了检测上线,具有分离表征淀粉颗粒的潜力。此外,该文研究了载液组成对淀粉颗粒分离表征的影响;通过光学显微镜验证了构建的AF4系统在微米尺度上对淀粉颗粒粒径分布的表征能力。最后,采用商品化的AF4系统串联多角度激光光散射检测器和示差折光检测器对3种淀粉分子进行了分离表征,考察了淀粉的溶解温度对其表征结果的影响。在摩尔质量10 ⁶~10⁸ g/mol范围内,红薯和莲子淀粉的回转半径和水合半径的比值(R_g/R_h)在0.9~1.1之间,大米淀粉的R_g/R_h在1.2~1.4之间。实验结果证明构建的AF4系统是一种快速、准确的淀粉颗粒粒径表征方法,与商品化的AF4系统结合可为研究淀粉尺寸分布与其功能性质之间的关系提供技术支持。

Analysis of Molar Substitution of Hydroxybutyl Group by Zeisel Reaction in Starch Ethers

A new etherified starch, δ-hydroxybutyl starch (δ-HBS), was prepared by utilising 4-chlorobutan-1-ol as the etherifying reagent. The method of Zeisel gas chromatography for the determination of the molar substitution was described. This technique offers a simple and rapid method for quantitative analysis with reproducible results. Meanwhile, the mechanism of the Zeisel reaction was also investigated.

Thermoresponsive Starch for the Flocculation of Oil Sands Mature Fine Tailings

The reclamation of land and recovery of water from tailing ponds created during bitumen extraction from oil sands is a major technical and environmental challenge. In the current study, thermoresponsive hydroxybutylated (HB) corn starch (HB-CS) and potato starch (HB-PS), with lower critical solution temperatures (LCSTs) ranging from 36 to 45 °C, were examined as flocculants for oil sands mature fine tailings (MFT). The ability of different doses of the HB-CS and HB-PS to flocculate 2 and 10 wt % MFT, prepared by diluting 35 wt % MFT in tap water, in terms of the initial settling rate (ISR), supernatant turbidity (ST), sediment solids content (SSC), and water recovery (WR), was examined at temperatures below and above their LCSTs. The thermoresponsive HB-CS and HB-PS were good flocculants of MFT, and their thermoresponsive behavior was essential for optimal results in that they were considerably more effective in several aspects at temperatures above their LCSTs than below. In terms of ISRs, the HB-PS was a considerably better flocculant than the HB-CS, and this was especially so with the 10 wt % MFT. With the HB-PS, the ISR was lower when using diluted MFT prepared with tap water as opposed to simulated oil sands process water.

A facile method to control the phase behavior of hydroxypropyl cellulose

We report a facile chemical method to convert the hydroxyl groups of hydroxypropyl cellulose (HPC) into carbamates. It was achieved by the reaction of HPC with N-methyl carbamoylimidazole, which is a safe and easy to handle replacement for the particularly hazardous reagent methyl isocyanate. Using a series of HPC with a range of molar substitution of hydroxypropyl groups, we synthesized HPC methylcarbamates showing lower critical solution temperature (LCST) in the range between 94 and 15 °C. A linear dependence of LCST versus methylcarbamate degree of substitution is observed. The lower the initial hydroxypropyl content of HPC, the greater the effect of methylcarbamate on the LCST. Surface tension study showed that methylcarbamate modification has an insignificant effect on the hydrophilic-hydrophobic balance of the macromolecules below LCST unless the molecular substitution of hydroxypropyl groups is so low (0.8) that the native cellulose OH groups can react with N-methyl carbamoylimidazole.

Facile design and development of photoluminescent graphene quantum dots grafted dextran/glycol-polymeric hydrogel for thermoresponsive triggered delivery of buprenorphine on pain management in tissue implantation

A novel nano-formulations of biocompatible, biodegradable and thermo-responsive graphene quantum dots (GQDs) loaded dextran/poly(N-isopropylacrylamide) (Dex/PNIPAM) copolymeric matrix was synthesized and analyzed the materials characterization, sustained drug delivery system, tissue feasibility in the tissue implantation site. This research report was aimed to grafting and functionalizing thermo-responsive (Dex/PNIPAM) copolymeric composite with presence of graphene quantum dots to achieve thermal responsive drug delivery (TrDD) with no harm effect in the implantation site. The synthesized GQD by using ionic liquid were evaluated by spectroscopic (DLS, PL, XRD and Raman spectroscopy) and Transmission electron microscopic analysis (TEM). The ultra-small GQDs loaded Dex/PNIPAM and was appeared to be asymmetric and open uniform porous structure, which can be significantly favorable for cell uptake and greatly influenced to be an effective drug carrier into the cellular compartment with good fluid flow. The PNIPAM polymeric composite were exhibited sustained and enhanced drug release percentages with increasing temperature at above low critical solution temperature (LCST) is 39 °C comparable to the cumulative drug release profile of below LCST (32 °C), which demonstrated that thermo-responsive polymer was played a significant role in the delivery system. The treated group of GQDs-Dex/PNIPAM was observed that no inflammation and shows noteworthy stromal cell infiltration, demonstrating that the synthesized drug carriers did not harm to the nerves and tissues and only was responsible for the pain management.