Characteristics of cellulose nanofibers isolated from rubberwood and empty fruit bunches of oil palm using chemo-mechanical process

In the present study, chemical-physical properties of nanofibers isolated from rubberwood (Hevea brasiliensis) and empty fruit bunches (EFB) of oil palm (Elaeis guineensis) were analyzed by microscopic, spectroscopic, thermal and X-ray diffraction methods. The isolation was achieved using chemo-mechanical processes. Microscopy study showed that the diameters of the nanofibers isolated from the EFB ranged from 5 to 40 nm while those of the nanofibers isolated from rubberwood had a wider range (10–90 nm). Fourier transform infrared spectroscopy study demonstrated that almost all the lignin and most of the hemicellulose were removed during the chemical treatments. X-ray diffraction analysis revealed that the crystallinity of the studied nanofibers increased after the chemo-mechanical isolation process. The results of thermogravimetric analysis showed that the nanofibers isolated from both sources had higher thermal stability than those of the bleached pulp and untreated fibers.     

Thermal characterization and electrical properties of Fe-modified cellulose long fibers and micro crystalline cellulose

Thermal properties of polylactic acid (PLA) filled with Fe-modified cellulose long fibers (CLF) and microcrystalline cellulose (MCC) were studied using thermo gravimetric analysis (TG), differential scanning calorimetry, and dynamic mechanical analysis (DMA). The Fe-modified CLFs and MCCs were compared with unmodified samples to study the effect of modification with Fe on electrical conductivity. Results from TG showed that the degradation temperature was higher for all composites when compared to the pure PLA and that the PLA composites filled with unmodified celluloses resulted in the best thermal stability. No comparable difference was found in glass transition temperature (T _g) and melting temperature (T _m) between pure PLA and Fe-modified and unmodified CLF- and MCC-based PLA biocomposites. DMA results showed that the storage modulus in glassy state was increased for the biocomposites when compared to pure PLA. The results obtained from a femtostat showed that electrical conductivity of Fe-modified CLF and MCC samples were higher than that of unmodified samples, thus indicating that the prepared biocomposites have potential uses where conductive biopolymers are needed. These modified fibers can also be tailored for fiber orientation in a matrix when subjected to a magnetic field.     

Microscale immunoaffinity SPE and MEKC in fast determination of testosterone in male urine

Conventional methods for the determination of testosterone in body fluids typically suffer from poor recovery, lack of specificity, complex sample pretreatment, or the need for derivatization. Here, a simple, specific, and fast analysis method for testosterone was developed, with a methodology based on testosterone-specific immunoaffinity SPE (IA-SPE) and subsequent analysis by partial filling MEKC (PF-MEKC). An immunosorbent consisting of a recombinant antitestosterone Fab fragment covalently attached to activated Sepharose was prepared. IA-SPE and PF-MEKC were set up in hyphenated and off-line constructions, and the applicability of the two constructions in analysis of testosterone in male urine was investigated. The results obtained with the hyphenated construction proved to be only indicative of the presence of testosterone. The off-line IA-SPE and PF-MEKC construction, however, was successfully used in the determination of free testosterone in male urine samples after enzymatic hydrolysis of the glucuronide conjugates. Except for the hydrolysis reaction, no sample pretreatment was required. After hydrolysis, the overall analysis time per sample was only 14 min. The off-line IA-SPE and PF-MEKC method proved to be robust, sensitive (LOQ 35 mug/L), and specific, enabling separation of testosterone from four related steroids. Thus, it provides attractive features when compared to traditional methods for determination of testosterone in male urine.     

Preparation and characterization of water-redispersible nanofibrillated cellulose in powder form

Water-redispersible, nanofibrillated cellulose (NFC) in powder form was prepared from refined, bleached beech pulp (RBP) by carboxymethylation (c) and mechanical disintegration (m). Two routes were examined by altering the sequence of the chemical and mechanical treatment, leading to four different products: RBP-m and RBP-mc (route 1), and RBP-c and RBP-cm (route 2). The occurrence of the carboxymethylation reaction was confirmed by FT-IR spectrometry and ¹³C solid state NMR (¹³C CP-MAS) spectroscopy with the appearance of characteristic signals for the carboxylate group at 1,595 cm⁻¹ and 180 ppm, respectively. The chemical modification reduced the crystallinity of the products, especially for those of route 2, as shown by XRD experiments. Also, TGA showed a decrease in the thermal stability of the carboxymethylated products. However, sedimentation tests revealed that carboxymethylation was critical to obtain water-redispersible powders: the products of route 2 were easier to redisperse in water and their aqueous suspensions were more stable and transparent than those from route 1. SEM images of freeze-dried suspensions from redispersed RBP powders confirmed that carboxymethylation prevented irreversible agglomeration of cellulose fibrils during drying. These results suggest that carboxymethylated and mechanically disintegrated RBP in dry form is a very attractive alternative to conventional NFC aqueous suspensions as starting material for derivatization and compounding with (bio)polymers.     

Functional Nanocomposite Films of Poly(Lactic Acid) with Well-Dispersed Chitin Nanocrystals Achieved Using a Dispersing Agent and Liquid-Assisted Extrusion Process

The development of bio-based nanocomposites is of high scientific and industrial interest, since they offer excellent advantages in creating functional materials. However, dispersion and distribution of the nanomaterials inside the polymer matrix is a key challenge to achieve high-performance functional nanocomposites. In this context, for better dispersion, biobased triethyl citrate (TEC) as a dispersing agent in a liquid-assisted extrusion process was used to prepare the nanocomposites of poly (lactic acid) (PLA) and chitin nanocrystals (ChNCs). The aim was to identify the effect of the TEC content on the dispersion of ChNCs in the PLA matrix and the manufacturing of a functional nanocomposite. The nanocomposite film’s optical properties; microstructure; migration of the additive and nanocomposites’ thermal, mechanical and rheological properties, all influenced by the ChNC dispersion, were studied. The microscopy study confirmed that the dispersion of the ChNCs was improved with the increasing TEC content, and the best dispersion was found in the nanocomposite prepared with 15 wt% TEC. Additionally, the nanocomposite with the highest TEC content (15 wt%) resembled the mechanical properties of commonly used polymers like polyethylene and polypropylene. The addition of ChNCs in PLA-TEC15 enhanced the melt viscosity, as well as melt strength, of the polymer and demonstrated antibacterial activity.     

(Z)-1-Aryl-1-haloalkenes as intermediates in the Vilsmeier haloformylation of aryl ketones

[reaction: see text] Vilsmeier reagents give (Z)-1-aryl-1-haloalkenes from aryl ketones bearing an electron-donating substituent at the ortho- or para-position. These haloalkenes are intermediates in the Vilsmeier haloformylation of the aryl ketones. Another reaction mechanistic pathway is thus available in certain Vilsmeier haloformylations, in competition with the commonly accepted route by way of an enaminoketone.     

On the Mechanism of the Reactivity of 1,3‐Dialkylimidazolium Salts under Basic to Acidic Conditions: A Combined Kinetic and Computational Study

Comprehensive spectroscopic kinetic studies illustrate an alternative mechanism for the traditional free‐carbene intermediated H/D exchange reaction of 1,3‐dialkylimidazolium salts under neutral (D₂O) and acidic conditions (DCl/D₂O 35 wt % solution). The deuteration of high purity [bmim]Cl in D₂O is studied at different temperatures, in absence of catalyst or impurities, to yield an activation energy. DFT transition‐state modelling, of a small water cluster and [bmim] cation, also yields an activation energy which strongly supports the proposed mechanism. The presence of basic impurities are shown to significantly enhance the exchange reaction, which brings into question the need for further analysis of technical purities of ionic liquids and the implications for a wide range of chemical reactions in such media.     

The in vitro Pulmonary Deposition of a Budesonide γ-Cyclodextrin Inclusion Complex

The interest in dry powder inhalers (DPIs) has recently increasedbecause the problems associated with the propellants used in pressurized metered-dose inhalers (PMDIs) will be avoided. Cyclodextrins (CDs) may be used as excipients in inhalation powders;e.g., in order to increase the solubility, stability and absorption of an inhaled drug. In thepresent study, the effect of complexation of budesonide with -CD on its pulmonary deposition wasstudied in vitro. In the presence of -CD, the aqueous solubility of budesonidefollowed B_S-type phase-solubility behaviour. A precipitationcomplexation method was used to prepare the solid budenoside/-CD complexes. The pulmonary in vitrodeposition of budenoside was evaluated after inhalation of plain budesonide and budenoside/-CDcomplexes (lactose carrier used in both formulations) by using the ``Andersen' cascadeimpactor. The novel Taifun® was used as the DPI. The respirable fractionsof the emitted budesonide dose (initially and after the storage in 40 °C, RH 75%) werecomparable for both plain budesonide and budesonide/-CD complexes. The present studyindicates that a drug/CD-complex can be used in inhalation powderswithout lowering the pulmonary deposition of the drug.     

Neurosteroids: Structure-Uptake Relationships and Computational Modeling of Organic Anion Transporting Polypeptides (OATP)1A2

In this study, we investigated the delivery of synthetic neurosteroids into MCF-7 human breast adenocarcinoma cells via Organic Anionic Transporting Polypeptides (OATPs) (pH 7.4 and 5.5) to identify the structural components required for OATP-mediated cellular uptake and to get insight into brain drug delivery. Then, we identified structure-uptake relationships using in-house developed OATP1A2 homology model to predict binding sites and modes for the ligands. These binding modes were studied by molecular dynamics simulations to rationalize the experimental results. Our results show that carboxylic acid needs to be at least at 3 carbon-carbon bonds distance from amide bond at the C-3 position of the androstane skeleton and have an amino group to avoid efflux transport. Replacement of hydroxyl group at C-3 with any of the 3, 4, and 5-carbon chained terminal carboxylic groups improved the affinity. We attribute this to polar interactions between carboxylic acid and side-chains of Lys33 and Arg556. The additional amine group showed interactions with Glu172 and Glu200. Based on transporter capacities and efficacies, it could be speculated that the functionalization of acetyl group at the C-17 position of the steroidal skeleton might be explored further to enable OAT1A2-mediated delivery of neurosteroids into the cells and also across the blood-brain barrier.