scholarly journals Esterification of Alginate with Alkyl Bromides of Different Carbon Chain Lengths via the Bimolecular Nucleophilic Substitution Reaction: Synthesis, Characterization, and Controlled Release Performance

Polymers ◽  
2021 ◽  
Vol 13 (19) ◽  
pp. 3351
Author(s):  
Xiuqiong Chen ◽  
Qingmei Zhu ◽  
Chang Liu ◽  
Dongze Li ◽  
Huiqiong Yan ◽  
...  
Keyword(s):  
Sustained Release ◽  
Nucleophilic Substitution ◽  
Drug Loading ◽  
Carbon Chain ◽  
Critical Aggregation Concentration ◽  
Carbon Chain Length ◽  
Hydrodynamic Diameter ◽  
Ester Derivative ◽  
Sn2 Reaction ◽  
Alkyl Bromides

To extend the alginate applicability for the sustained release of hydrophobic medicine in drug delivery systems, the alkyl alginate ester derivative (AAD), including hexyl alginate ester derivative (HAD), octyl alginate ester derivative (OAD), decyl alginate ester derivative (DAD), and lauryl alginate ester derivative (LAD), were synthesized using the alkyl bromides with different lengths of carbon chain as the hydrophobic modifiers under homogeneous conditions via the bimolecular nucleophilic substitution (SN2) reaction. Experimental results revealed that the successful grafting of the hydrophobic alkyl groups onto the alginate molecular backbone via the SN2 reaction had weakened and destroyed the intramolecular hydrogen bonds, thus enhancing the molecular flexibility of the alginate, which endowed the AAD with a good amphiphilic property and a critical aggregation concentration (CAC) of 0.48~0.0068 g/L. Therefore, the resultant AAD could form stable spherical self-aggregated micelles with the average hydrodynamic diameter of 285.3~180.5 nm and zeta potential at approximately −44.8~−34.4 mV due to the intra or intermolecular hydrophobic associations. With the increase of the carbon chain length of the hydrophobic side groups, the AAD was more prone to self-aggregation, and therefore was able to achieve the loading and sustained release of hydrophobic ibuprofen. Additionally, the swelling and degradation of AAD microcapsules and the diffusion of the loaded drug jointly controlled the release rate of ibuprofen. Meanwhile, the AAD also displayed low cytotoxicity to the murine macrophage RAW264.7 cells. Thanks to the good amphiphilic property, colloidal interface activity, hydrophobic drug-loading performance, and cytocompatibility, the synthesized AAD exhibited a great potential for the development of hydrophobic pharmaceutical formulations.

Temperature-Responsive Self-Assemblies of ‘Kinked' Amphiphiles

2013 ◽  
Vol 66 (8) ◽  
pp. 899 ◽  
Author(s):  
Jennifer S. Squire ◽  
Grégory Durand ◽  
Lynne Waddington ◽  
Alessandra Sutti ◽  
Luke C. Henderson
Keyword(s):  
Temperature Response ◽  
Thermal Response ◽  
Carbon Chain ◽  
Critical Aggregation Concentration ◽  
Head Group ◽  
Hydrodynamic Diameter ◽  
Polar Head Group ◽  
Hydrophobic Region ◽  
Thermal Window ◽  
Starting Point

The synthesis of novel norbornane-based amphiphiles and the thermal response of their corresponding colloids is presented. It was found that the hydrodynamic diameter (DH) expansion or contraction of 1–4 in response to increasing temperature was governed by the length of the hydrophobic region possessed by the amphiphile (a 12 or 16 carbon chain). These data were used as a starting point to extend into an active tumour targeting system whereby two amphiphiles were modified to incorporate the oestrogen receptor antagonist Tamoxifen at the polar head group. This was achieved by a triazole moiety while both the C12 (18) or C16 (19) hydrophobic chains were incorporated as the hydrophobic region in an attempt to retain the response to thermal stimuli observed in our preliminary findings. These functionalised novel amphiphiles possessed critical aggregation concentration values of 510 and 19 µM, while aqueous self-assemblies of 56 and 106 nm for 18 and 19 were observed. Imaging by cryogenic transmission electron microscopy showed 18 to possess liposomal morphology, while 19, bearing a C16 hydrophobic portion, formed non-defined amorphous aggregates. Finally, the response to temperature of these assemblies was investigated with only the C12 variant 18 displaying a temperature response in the 5–55°C thermal window investigated.

scholarly journals Optimization of Tilmicosin-Loaded Nanostructured Lipid Carriers Using Orthogonal Design for Overcoming Oral Administration Obstacle

Pharmaceutics ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 303
Author(s):  
Jia Wen ◽  
Xiuge Gao ◽  
Qian Zhang ◽  
Benazir Sahito ◽  
Hongbin Si ◽  
...  
Keyword(s):  
Oral Administration ◽  
Oral Delivery ◽  
Bacterial Infections ◽  
Cold Water ◽  
Orthogonal Design ◽  
Drug Loading ◽  
Absorption Efficiency ◽  
Nanostructured Lipid Carriers ◽  
Orthogonal Experimental Design ◽  
Hydrodynamic Diameter

Tilmicosin (TMS) is widely used to treat bacterial infections in veterinary medicine, but the clinical effect is limited by its poor solubility, bitterness, gastric instability, and intestinal efflux transport. Nanostructured lipid carriers (NLCs) are nowadays considered to be a promising vector of therapeutic drugs for oral administration. In this study, an orthogonal experimental design was applied for optimizing TMS-loaded NLCs (TMS-NLCs). The ratios of emulsifier to mixed lipids, stearic acid to oleic acid, drugs to mixed lipids, and cold water to hot emulsion were selected as the independent variables, while the hydrodynamic diameter (HD), drug loading (DL), and entrapment efficiency (EE) were the chosen responses. The optimized TMS-NLCs had a small HD, high DL, and EE of 276.85 ± 2.62 nm, 9.14 ± 0.04%, and 92.92 ± 0.42%, respectively. In addition, a low polydispersity index (0.231 ± 0.001) and high negative zeta potential (−31.10 ± 0.00 mV) indicated the excellent stability, which was further demonstrated by uniformly dispersed spherical nanoparticles under transmission electron microscopy. TMS-NLCs exhibited a slow and sustained release behavior in both simulated gastric juice and intestinal fluid. Furthermore, MDCK-chAbcg2/Abcb1 cell monolayers were successfully established to evaluate their absorption efficiency and potential mechanism. The results of biodirectional transport showed that TMS-NLCs could enhance the cellular uptake and inhibit the efflux function of drug transporters against TMS in MDCK-chAbcg2/Abcb1 cells. Moreover, the data revealed that TMS-NLCs could enter the cells mainly via the caveolae/lipid raft-mediated endocytosis and partially via macropinocytosis. Furthermore, TMS-NLCs showed the same antibacterial activity as free TMS. Taken together, the optimized NLCs were the promising oral delivery carrier for overcoming oral administration obstacle of TMS.

Ionic liquid-biosurfactant blends as effective dispersants for oil spills: Effect of carbon chain length and degree of saturation

2021 ◽  
pp. 117119
Author(s):  
Mansoor Ul Hassan Shah ◽  
Ambavaram Vijaya Bhaskar Reddy ◽  
Suzana Yusup ◽  
Masahiro Goto ◽  
Muhammad Moniruzzaman
Keyword(s):  
Ionic Liquid ◽  
Chain Length ◽  
Oil Spills ◽  
Carbon Chain ◽  
Degree Of Saturation ◽  
Carbon Chain Length

Preparation, evaluation, and in vitro release of chitosan-alginate tanshinone self-microemulsifying sustained-release microcapsules

2020 ◽  
pp. 1-9
Author(s):  
Yunhong Wang ◽  
Rong Hu ◽  
Yanlei Guo ◽  
Weihan Qin ◽  
Xiaomei Zhang ◽  
...  
Keyword(s):  
Drug Release ◽  
Sustained Release ◽  
Release Rate ◽  
Orthogonal Design ◽  
Drug Loading ◽  
In Vitro Release ◽  
Core Material ◽  
Evaluation Indexes ◽  
Vitro Release

OBJECTIVE: In this study we explore the method to prepare tanshinone self-microemulsifying sustained-release microcapsules using tanshinone self-microemulsion as the core material, and chitosan and alginate as capsule materials. METHODS: The optimal preparation technology of chitosan-alginate tanshinone self-microemulsifying sustained-release microcapsules was determined by using the orthogonal design experiment and single-factor analysis. The drug loading and entrapment rate were used as evaluation indexes to assess the quality of the drug, and the in vitro release rate was used to evaluate the drug release performance. RESULTS: The best technology of chitosan-alginate tanshinone self-microemulsifying sustained-release microcapsules is as follows: the concentration of alginate is 1.5%, the ratio of tanshinone self-microemulsion volume to alginate volume to chitosan mass is 1:1:0.5 (ml: ml: g), and the best concentration of calcium chloride is 2.0%. To prepare the microcapsules using this technology, the drug loading will be 0.046%, the entrapment rate will be 80.23%, and the 24-hour in vitro cumulative release rate will be 97.4%. CONCLUSION: The release of the microcapsules conforms to the Higuchi equation and the first-order drug release model and has a good sustained-release performance.

scholarly journals Development of In Situ Self-Assembly Nanoparticles to Encapsulate Lopinavir and Ritonavir for Long-Acting Subcutaneous Injection

Pharmaceutics ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 904
Author(s):  
Irin Tanaudommongkon ◽  
Asama Tanaudommongkon ◽  
Xiaowei Dong
Keyword(s):  
Sustained Release ◽  
Trough Concentration ◽  
Self Assembly ◽  
Subcutaneous Injection ◽  
Drug Loading ◽  
Entrapment Efficiency ◽  
Long Acting

Most antiretroviral medications for human immunodeficiency virus treatment and prevention require high levels of patient adherence, such that medications need to be administered daily without missing doses. Here, a long-acting subcutaneous injection of lopinavir (LPV) in combination with ritonavir (RTV) using in situ self-assembly nanoparticles (ISNPs) was developed to potentially overcome adherence barriers. The ISNP approach can improve the pharmacokinetic profiles of the drugs. The ISNPs were characterized in terms of particle size, drug entrapment efficiency, drug loading, in vitro release study, and in vivo pharmacokinetic study. LPV/RTV ISNPs were 167.8 nm in size, with a polydispersity index of less than 0.35. The entrapment efficiency was over 98% for both LPV and RTV, with drug loadings of 25% LPV and 6.3% RTV. A slow release rate of LPV was observed at about 20% on day 5, followed by a sustained release beyond 14 days. RTV released faster than LPV in the first 5 days and slower than LPV thereafter. LPV trough concentration remained above 160 ng/mL and RTV trough concentration was above 50 ng/mL after 6 days with one subcutaneous injection. Overall, the ISNP-based LPV/RTV injection showed sustained release profiles in both in vitro and in vivo studies.

Synthesis and Interfacial Activity of Alkyl Polyoxypropylene Sulfonate for Chemical Combination Flooding

2012 ◽  
Vol 550-553 ◽  
pp. 3-9
Author(s):  
You Yi Zhu ◽  
Zhang Lei Ning ◽  
Qing Feng Hou ◽  
Ming Lei ◽  
Guo Qing Jian
Keyword(s):  
Salt Tolerance ◽  
Interfacial Tension ◽  
Divalent Cation ◽  
Carbon Chain ◽  
Carbon Chain Length ◽  
Formation Water ◽  
Interfacial Activity ◽  
Chemical Combination ◽  
Ultralow Interfacial Tension ◽  
Oil Formation

A serious of alkyl polyoxypropylene sulfonate surfactant was synthesized. The O/W interfacial activity of alkyl polyoxypropylene sulfonate surfactant was investigated. The results showed that the interfacial tension of Indonesia crude oil/formation water could reach ultralow level (10-3mN/m order of the magnitude) under weak alkali (Na2CO3) concentration from 0.4wt% to 1.0wt% with C16PO8S, C16PO10S, C18PO8S and C18PO10S alkyl polyoxypropylene sulfonate respectively. These surfactants showed good interface activity and salt and divalent cation tolerance ability. Combinations of alkyl polyoxypropylene sulfanate homologies with different carbon chain length could significantly improve the interface activity. The IFT of Indonesia oil/formation water could reach ultralow interfacial tension under alkali free conditions. The combination of alkyl polyoxypropylene sulfonate surfactant with petroleum sulfonate could improve the salt tolerance ability of formula.

Controlling the Secondary Assembly of Porous Anionic Uranyl-organic Polyhedra through Organic Cationic Templates

2021 ◽  
Author(s):  
Liwen Zeng ◽  
Kong-qiu Hu ◽  
Zhi-wei Huang ◽  
Lei Mei ◽  
Xianghe Kong ◽  
...  
Keyword(s):  
Chain Length ◽  
Carbon Chain ◽  
Carbon Chain Length ◽  
Organic Templates ◽  
Secondary Assembly

Herein, we report a new uranyl-organic polyhedron U4L4 (L=BTPCA) assembled from uranyl and a semirigid tritopic ligand. By adjusting the carbon chain length of the organic templates, two complexes can...

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