Structural and rheological characterizations of nanoparticles of environment-sensitive hydrophobic alginate in aqueous solution

Coexistence of aggregates and flat states of hydrophobically modified sodium alginate at an oil/water interface: A molecular dynamics study

Hydrophobically modified sodium alginate stabilizes benzene in water emulsions. The stability of the emulsion is related to the interface properties at the mesoscopic scale, but the details of the polymer adsorption, conformation and organization at oil/water interfaces at the microscopic scale remain largely elusive. In this study, hydrophobically modified sodium alginate was used as a representative of amphiphilic polymers for prediction of distribution of HMSA at the oil/water interface by coarse-grained molecular dynamics simulation. The result showed that driven by the interaction energy between the hydrophobic segment and benzene, HMSA will actively accumulate at the oil/water interface. The HMSA molecules parallel to the oil/water interface prevent the hydrophobic segments in the micelles from approaching the oil/water interface, so that the micelles can exist stably by steric hindrance. This study would be helpful to understand the aggregation behavior of amphiphilic polymers at the oil/water interface, these results can have applications in diverse sectors such as drug, food industry, where polymers are used to stabilize emulsions.

Effect of Rheological Properties of Polymer Solution on Polymer Flooding Characteristics

Polymer flooding is an appropriate enhanced oil recovery (EOR) process that can increase macroscopic sweep efficiency. We examined two polymeric superpushers at different salinities (10,000 and 42,000 ppm of NaCl and 18,000 ppm of CaCl₂) and temperatures (30 to 75 °C) as polymer-flooding agents for the EOR process. Rheological and thixotropic tests were attempted to find shear viscosity change when the polymer solutions were introduced under different salinity and temperatures, followed by describing the rheological behavior with the two most common rheological models used for polymer solutions, and then a quadratic model with Design-Expert to detect the effective parameters. Core flooding tests were conducted afterward to determine the final proposed fluid. An increase in the concentration of monovalent ions and the addition of divalent ions adversely affected both types of polymers used, which was similar to the effects of a temperature increase. The Flopaam 3630S at 1000 ppm has more stability under harsh conditions and enables 22% and 38% oil recovery in carbonate and sandstone core rocks, respectively. Consequently, Flopaam 3630S can be the perfect polymer agent for different chemical flooding procedures in high-salinity oil reservoirs.

3D-Printed Concentration-Controlled Microfluidic Chip with Diffusion Mixing Pattern for the Synthesis of Alginate Drug Delivery Microgels

Alginate as a good drug delivery vehicle has excellent biocompatibility and biodegradability. In the ionic gelation process between alginate and Ca²⁺, the violent reaction is the absence of a well-controlled strategy in the synthesizing calcium alginate (CaA) microgels. In this study, a concentration-controlled microfluidic chip with central buffer flow was designed and 3D-printed to well-control the synthesis process of CaA microgels by the diffusion mixing pattern. The diffusion mixing pattern in the microfluidic chip can slow down the ionic gelation process in the central stream. The particle size can be influenced by channel length and flow rate ratio, which can be regulated to 448 nm in length and 235 nm in diameter. The delivery ratio of Doxorubicin (Dox) in CaA microgels are up to 90% based on the central stream strategy. CaA@Dox microgels with pH-dependent release property significantly enhances the cell killing rate against human breast cancer cells (MCF-7). The diffusion mixing pattern gives rise to well-controlled synthesis of CaA microgels, serving as a continuous and controllable production process for advanced drug delivery systems.

Targeted transport of nanocarriers into brain for theranosis with rabies virus glycoprotein-derived peptide

For successful theranosis of brain diseases, limited access of therapeutic molecules across blood-brain barrier (BBB) needs be overcome in brain delivery. Currently, peptide derivatives of rabies virus glycoprotein (RVG) have been exploited as delivery ligands to transport nanocarriers across BBB and specifically into the brain. The targeting peptides usually conjugate to the nanocarrier surface, and the cargoes, including siRNA, miRNA, DNA, proteins and small molecular chemicals, are complexed or encapsulated in the nanocarriers. The peptide ligand of the RVG-modified nanocarriers introduces the conjugated targeted-delivery into the brain, and the cargoes are involved in disease theranosis. The peptide-modified nanocarriers have been applied to diagnose and treat various brain diseases, such as glioma, Alzheimer's disease, ischemic injury, protein misfolding diseases etc. Since the targeting delivery system has displayed good biocompatibility and desirable therapeutic effect, it will raise a potential application in treating brain diseases.

Effect of carboxymethylation on rheological and drug release characteristics of Terminalia catappa gum

The carboxymethylation of galactomannans, arabinogalactans, arbinoxylan, etc is known to modify solubility, swelling index, rheological behaviour, powder characteristics, etc. Therefore, an attempt had been made to study the effect of carboxymethylation on Terminalia catappa (TC) gum. For this, modified Williamson synthesis reaction was utilized employing Quality by Design (QbD) approach. Grafting of carboxymethyl group on Terminalia catappa was confirmed by ATR-FTIR, H¹NMR and DSC analyses. The rheological attributes revealed that the carboxymethylation of TC lowers the viscosity, enhance thermal stability (high activation energy), disentanglement was near to re-entanglement, and weak gelling characteristic. However, the soluble fluconazole loaded gel formulation of CMTC showed diffusion based kinetic model indicating good reservoir for effective application on skin/tissue surfaces.