Muhammad Moniruzzaman

Recent advances in exploiting ionic liquids for biomolecules: Solubility, stability and applications.

The technological utility of biomolecules (e.g. proteins, enzymes and DNA) can be significantly enhanced by combining them with ionic liquids (ILs) – potentially attractive ”green“ and ”designer“ solvents – rather than using in conventional organic solvents or water. In recent years, ILs have been used as solvents, cosolvents, and reagents for biocatalysis, biotransformation, protein preservation and stabilization, DNA solubilization and stabilization, and other biomolecule‐based applications. Using ILs can dramatically enhance the structural and chemical stability of proteins, DNA, and enzymes. This article reviews the recent technological developments of ILs in protein‐, enzyme‐, and DNA‐based applications. We discuss the different routes to increase biomolecule stability and activity in ILs, and the design of biomolecule‐friendly ILs that can dissolve biomolecules with minimum alteration to their structure. This information will be helpful to design IL‐based processes in biotechnology and the biological sciences that can serve as novel and selective processes for enzymatic reactions, protein and DNA stability, and other biomolecule‐based applications.

Ionic liquids as a potential tool for drug delivery systems

The pharmaceutical industries face a series of challenges in the delivery of many newly developed drug molecules because of their low solubility, bioavailability, stability and polymorphic conversion. These limitations are further exacerbated when drug molecules are insoluble or sparingly soluble in water and most pharmaceutically accepted organic solvents. To address these limitations, innovation is required in the pharmaceutical sciences for the formulation of drugs, solvents or systems for effective drug delivery. Fortunately, in the past few years, ionic liquids (ILs)—a novel class of environmentally benign and tailor-made solvents—have been increasingly exploited as solvents, co-solvents and/or materials in the fields of pharmaceutical drug delivery and active pharmaceutical ingredient (API) formulation because of their unique and tunable physicochemical and biological properties. The use of ILs can markedly improve the pharmacokinetic and pharmacodynamic properties of drugs. To highlight the potential of ILs as a drug delivery/formulation tool, this review gives an overview of the application of ILs to address critical pharmaceutical challenges, including the low solubility, polymorphism and bioavailability of drugs. This review is not intended to be comprehensive, but rather to present the efforts made in using ILs in drug solubility, API formulation and drug delivery, including topical, transdermal and oral delivery, with particular emphasis on recent developments.

Ionic liquids assisted processing of renewable resources for the fabrication of biodegradable composite materials

In recent years, the utilization of renewable resources, particularly lignocellulosic biomass based raw materials, to replace synthetic materials/polymers for the manufacture of green materials has gained increased worldwide interest due to growing global environmental awareness, concepts of sustainability and the absence of conflict between food and chemical/materials production. However, structural heterogeneity and the presence of networks of inter- and intra-molecular interactions in biopolymer matrices remain unsolved challenges to clean pretreatment for biocomposite processing. A number of techniques including physical, physico-chemical and chemical methods have been investigated for the pretreatment of renewable resources. Most of these methods require high temperatures and pressures, as well as highly concentrated chemicals for the pretreatment process. Fortunately, ionic liquids (ILs) – potentially attractive “green” recyclable alternatives to environmentally harmful organic solvents – have been increasingly exploited as solvents and/or (co)solvents and/or reagents for biopolymer processing. Compared to conventional approaches, ILs in processing biodegradable composites exhibit many advantages such as being noncorrosive and nonvolatile, having excellent dissolution power under relatively mild conditions and high thermal stability. Presently, a wide range of different approaches have been explored to further improve the performance of ILs processing of biobased polymers for composites manufacturing. The main goal of this review is to present recent technological developments in which the advantages of ILs as processing solvents for biopolymers for the production of a plethora of green composites have been gradually realized. It is hoped that the present article will inspire new ideas and new approaches in ILs-assisted processing of renewable resources for green composite production.

Ionic liquid-mediated transcutaneous protein delivery with solid-in-oil nanodispersions

As a potentially safe and non-invasive vaccination method, transcutaneous immunization represents an attractive alternative to conventional vaccine delivery by injection. However, the development of transcutaneous immunization has remained a challenge for a large number of hydrophilic macromolecules including protein and peptide antigens. We report a novel ionic liquid (IL)-mediated transcutaneous vaccine formulation consisting of a solid-in-oil (S/O) nanodispersion of antigen coated with pharmaceutically accepted surfactants dispersed in IL-containing oil. The introduction of the IL [C12mim][Tf2N] (1-dodecyl-3-methyl imidazolium bis(trifluoromethyl sulfonyl) amide) as a penetration enhancer in the formulation significantly enhanced the skin permeability of ovalbumin (OVA), a model antigen. It was also found that the IL-mediated S/O nanodispersion obtained high levels of OVA-specific serum IgG compared with both S/O nanodispersions without IL and PBS control. These findings clearly indicate that ILs – which are potentially attractive “green” and “designer” solvents – could serve as potential skin penetration enhancers in transcutaneous vaccination for hydrophilic macromolecules.

Particulate composites based on ionic liquid-treated oil palm fiber and thermoplastic starch adhesive

Pretreatment of lignocellulosic materials is a highly essential and critical task for the manufacturing of engineered composite panels. Recently, ionic liquids (ILs) have emerged as a promising green solvent for lignocellulosic biomass disintegration. In this work, the impact of IL pretreatment on the flexural and thermal properties of the thermo-molded biocomposite panels made from oil palm biomass residue and thermoplastic starch biopolymer as binder was studied. Oil palm fiber was pretreated with IL [emim][dep] (1-ethyl-3-methylimidazolium diethyl phosphate) and IL [bmim][Cl] (1-butyl-3-methylimidazolium chloride) prior to mixing with plasticized starch. The compounded mixture was then hot-pressed into composite panels. To understand the effect of IL pretreatment, lignocellulosic characterization, morphology, and thermogravimetric analysis of the untreated and treated fibers were performed. It was found that thermal stability of the oil palm biomass and the biocomposites was improved after IL pretreatment due to partial removal of hemicellulose and lignin from raw fiber. Moreover, pretreated biocomposites exhibited superior strength and modulus as compared to that of untreated sample as evidenced from flexural testing. The study plainly demonstrates that IL-assisted pretreatment could be an extremely attractive and clean technology for the efficient use of agro-based industrial waste in biocomposite field.

Kinetic study on microwave-assisted esterification of free fatty acids derived from Ceiba pentandra Seed Oil.

Recently, a great attention has been paid to advanced microwave technology that can be used to markedly enhance the biodiesel production process. Ceiba pentandra Seed Oil containing high free fatty acids (FFA) was utilized as a non-edible feedstock for biodiesel production. Microwave-assisted esterification pretreatment was conducted to reduce the FFA content for promoting a high-quality product in the next step. At optimum condition, the conversion was achieved 94.43% using 2wt% of sulfuric acid as catalyst where as 20.83% conversion was attained without catalyst. The kinetics of this esterification reaction was also studied to determine the influence of factors on the rate of reaction and reaction mechanisms. The results indicated that microwave-assisted esterification was of endothermic second-order reaction with the activation energy of 53.717kJ/mol.

Laccase Incorporated into PEG-PLA Polymer as Active and Stable Biocatalyst for Ionic Liquids Media

Laccase Y20 (EC.1.10.3.2) was coated with poly (ethylene glycol)-block-polylactide (PEG-PLA, MW = 27680) via water-in-oil emulsion, and the activity and stability of the resulting PEG-PLA-laccase complex have been compared to those for the native laccase and lyophilized native laccase in an ionic liquid (IL) [C2mim][PF6] (1-ethyl-3-methylimidazolium hexafluorophosphate. The formation of spherical PEG-PLA-laccase complex of 330-480 nm was demonstrated by scanning electron microscopy. This polymer-laccase complex retained most of its enzymatic catalytic activity and exhibited excellent storage stability in IL, with over 70% of its initial activity retained after 12 days of storage in IL at 40 °C, whereas it was about 20% for native laccase under the identical conditions. This strategy could be employed to fabricate polymer based composites materials with novel biological functions.

Ionic-Liquid-Based Paclitaxel Preparation: A New Potential Formulation for Cancer Treatment

Paclitaxel (PTX) injection (i.e., Taxol) has been used as an effective chemotherapeutic treatment for various cancers. However, the current Taxol formulation contains Cremophor EL, which causes hypersensitivity reactions during intravenous administration and precipitation by aqueous dilution. This communication reports the preliminary results on the ionic liquid (IL)-based PTX formulations developed to address the aforementioned issues. The formulations were composed of PTX/cholinium amino acid ILs/ethanol/Tween-80/water. A significant enhancement in the solubility of PTX was observed with considerable correlation with the density and viscosity of the ILs, and with the side chain of the amino acids used as anions in the ILs. Moreover, the formulations were stable for up to 3 months. The driving force for the stability of the formulation was hypothesized to be the involvement of different types of interactions between the IL and PTX. In vitro cytotoxicity and antitumor activity of the IL-based formulations were evaluated on HeLa cells. The IL vehicles without PTX were found to be less cytotoxic than Taxol, while both the IL-based PTX formulation and Taxol exhibited similar antitumor activity. Finally, in vitro hypersensitivity reactions were evaluated on THP-1 cells and found to be significantly lower with the IL-based formulation than Taxol. This study demonstrated that specially designed ILs could provide a potentially safer alternative to Cremophor EL as an effective PTX formulation for cancer treatment giving fewer hypersensitivity reactions.

Volumetric properties of binary mixtures of benzene with cyano-based ionic liquids

The objective of this study is to investigate the volumetric properties of the binary mixtures comprised benzene and two ionic liquids, 1-butyl-3-methylimidazolium thiocyanate ([BMIM][SCN]) and 1-butyl-3-methyl- imidazolium dicyanamide ([BMIM][N(CN)2](. Densities (ρ) and viscosities (μ) of the binary mixtures were measured over a temperature range of 293.15 to 323.15 K and at atmospheric pressure. Excess molar volumes and viscosity deviations were calculated from the experimental densities and viscosities values. The volumetric properties of the mixtures were changed significantly with the change of compositions and temperatures. It was also found that the value of excess molar volume and viscosity deviations were negative (-ve) over the entire range of compositions. The results have been interpreted in terms of molecular interactions of ILs and benzene.

Characterization and cytotoxicity evaluation of biocompatible amino acid esters used to convert salicylic acid into ionic liquids

Graphical abstract Figure. No Caption available. &NA; The technological utility of active pharmaceutical ingredients (APIs) is greatly enhanced when they are transformed into ionic liquids (ILs). API‐ILs have better solubility, thermal stability, and the efficacy in topical delivery than solid or crystalline drugs. However, toxicological issue of API‐ILs is the main challenge for their application in drug delivery. To address this issue, 11 amino acid esters (AAEs) were synthesized and investigated as biocompatible counter cations for the poorly water‐soluble drug salicylic acid (Sal) to form Sal‐ILs. The AAEs were characterized using 1H and 13C NMR, FTIR, elemental, and thermogravimetric analyses. The cytotoxicities of the AAE cations, Sal‐ILs, and free Sal were investigated using mammalian cell lines (L929 and HeLa). The toxicities of the AAE cations greatly increased with inclusion of long alkyl chains, sulfur, and aromatic rings in the side groups of the cations. Ethyl esters of alanine, aspartic acid, and proline were selected as a low cytotoxic AAE. The cytotoxicities of the Sal‐ILs drastically increased compared with the AAEs on incorporation of Sal into the cations, and were comparable to that of free Sal. Interestingly, the water miscibilities of the Sal‐ILs were higher than that of free Sal, and the Sal‐ILs were miscible with water at any ratio. A skin permeation study showed that the Sal‐ILs penetrated through skin faster than the Sal sodium salt. These results suggest that AAEs could be used in biomedical applications to eliminate the use of traditional toxic solvents for transdermal delivery of poorly water‐soluble drugs.