Development of Novel Lipid-Based Formulations for Water-Soluble Vitamin C versus Fat-Soluble Vitamin D3.

The aim of this study was to develop a facile and novel lipid-based formulation of vitamin C and vitamin D3. Liposomes loaded with vitamin C and D3 were characterized using transmission electron microscopy (TEM) and zeta potential measurements for evaluating morphology, particle size and physical stability. HPLC was employed to quantify the content of vitamin C and vitamin D3 in their liposomal forms. The UHPLC analysis of the lipid-based vitamin formulation is an easy and rapid method for the characterization as well as the quantification of all components. In addition, encapsulation efficiency, vitamin loading and stability analysis were performed by the UHPLC method, in order to evaluate the reliability of the optimized lipid-based formulation. The TEM results provided key support for the core type of liposome structure in the formulations, whereas the HPLC results indicated that the liposomal vitamin C and D3 systems were homogeneous, and did not undergo phase separation. Taken together, the results demonstrate that liposomal encapsulated vitamins (vitamin C and D3) possess a unilamellar vesicle morphology with uniform particle size, despite differences in the hydrophile-lipophile profiles of the vitamins. The highly efficient encapsulation properties of such liposomal constructs are proposed to contribute to enhanced vitamin bioavailability.

Comparison of the Moisture Adsorption Properties of Starch Particles and Flax Fiber Coatings for Energy Wheel Applications.

The adsorption-desorption behavior of flax fibers (FFs) is reported in this paper. FFs are a potential desiccant material for air-to-air energy wheels, which transfer heat and moisture in building heating, ventilation, and air conditioning (HVAC) systems. The raw FFs sample was subjected to physical modification, followed by complementary material characterization to understand the relationship between its structure and its moisture uptake performance. The surface and textural properties of the modified FFs were determined by gas adsorption (N2, H2O) and gravimetric liquid water swelling studies and further supported by spectroscopic (infrared and scanning electron microscopy) results. A FF-coated small-scale energy exchanger was used to determine the moisture transfer (or latent effectiveness; εl) using single-step and cyclic testing. The FF-coated exchanger had εl values of ∼10 and 40% greater compared to similar exchangers coated with starch particles (SPs) and silica gel (SG) reported in a previous study. The enhanced surface and textural properties, along with the complex compositional structure of FFs and its greater propensity to swell in water, account for the improved performance over SPs. Thus, FFs offer an alternative low-cost, environment-friendly, and sustainable biodesiccant for air-to-air energy wheel applications in buildings. The current study contributes to an improved understanding of the structure-function relationship of biodesiccants for such energy wheel applications.

Flax Biomass Conversion via Controlled Oxidation: Facile Tuning of Physicochemical Properties.

The role of chemical modification of pristine linen fiber (LF) on its physicochemical and adsorption properties is reported in this contribution. The surface and textural properties of the pristine LF and its peroxyacetic acid- (PAF) and chlorite-treated (CF) fiber forms were characterized by several complementary methods: spectroscopy (SEM, TEM, FT-IR, and XPS), thermal analysis (DSC and TGA), gas/water adsorption isotherms, and zeta potential (ξ). The results obtained reveal that the surface charge and textural properties (surface area and pore structure) of the LF material was modified upon chemical treatment, as indicated by changes in the biomass composition, morphology, ξ-values, and water/dye uptake properties of the fiber samples. Particularly, the pristine LF sample displays preferential removal efficiency (ER) of methylene blue (MB) dye with ER ~3-fold greater (ER~62%) as compared to the modified materials (CF or PAF; ER~21%), due to the role of surface charge of pectins and lignins present in pristine LF. At higher MB concentration, the relative ER values for LF (~19%) relative to CF or PAF (~16%) reveal the greater role of micropore adsorption sites due to the contributing effect of the textural porosity observed for the modified flax biomass at these conditions. Similar trends occur for the adsorption of water in the liquid vs. vapour phases. The chemical treatment of LF alters the polarity/charge of the surface functional groups, and pore structure properties of the chemically treated fibers, according to the variable hydration properties. The surface and textural properties of LF are altered upon chemical modification, according to the variable adsorption properties with liquid water (l) vs. water vapor (g) due to the role of surface- vs. pore-sites. This study contributes to an understanding of the structure-adsorption properties for pristine and oxidized flax fiber biomass. The chemical conversion of such biomass yields biomaterials with tunable surface and textural properties, as evidenced by the unique adsorption properties observed for pristine LF and its modified forms (CF and PAF). This study addresses knowledge gaps in the field by contributing insight on the relationship between structure and adsorption properties of such LF biomass in its pristine and chemically modified forms.

Hydration and Sorption Properties of Raw and Milled Flax Fibers.

The physicochemical and hydration properties of mechanically modified flax fibers (FFs) were investigated herein. Raw flax fibers (FF-R) were ball-milled and sieved through mesh with various aperture sizes (420, 210, and 125 µm) to achieve modified samples, denoted as FF-420, FF-210, and FF-125, respectively. The physicochemical and hydration properties of FF-R with variable particle sizes were characterized using several complementary techniques: microscopy (SEM), spectroscopy (FT-IR, XRD, and XPS), thermoanalytical methods (DSC and TGA), adsorption isotherms using gas/dye probes, and solvent swelling studies in liquid H2O. The hydration of FF biomass is governed by the micropore structure and availability of active surface sites, as revealed by the adsorption isotherm results and the TGA/DSC profiles of the hydrated samples. Gravimetric water swelling, water retention values, and vapor adsorption results provide further support that particle size reduction of FF-R upon milling parallels the changes in surface chemical and physicochemical properties relevant to adsorption/hydration in the modified FF materials. This study outlines a facile strategy for the valorization and tuning of the physicochemical properties of agricultural FF biomass via mechanical treatment for diverse applications in biomedicine, energy recovery, food, and biosorbents for environmental remediation.

Water Vapor Adsorption-Desorption Behavior of Surfactant-Coated Starch Particles for Commercial Energy Wheels.

This study reports on the adsorption (dehumidification)-desorption (humidification) behavior of cetylpyridinium bromide (CPB) coated starch particles (SPs), denoted as SP-CPB, as a potential desiccant material for air-to-air energy exchangers. CPB is a cationic surfactant with antibacterial activity that can be used to modify the surface properties of SPs, especially at variable CPB loading levels (SP-CPB0.5, SP-CPB2.5, and SP-CPB5.0, where the numeric suffix represents the synthetic loading level of CPB in mM). The SP-CPB0.5 sample displayed optimal surface area and pore structure properties that was selected for water sorption isotherm studies at 25 °C. The CPB-coated SPs sample (SP-CPB0.5) showed an improved water vapor uptake capacity compared to unmodified starch (SPs) and other desiccant systems such as high amylose starch (HAS15) and silica gel (SG13). Single-step and cyclic water vapor sorption tests were conducted using a small-scale exchanger coated with SP-CPB0.5. The calculated latent effectiveness values obtained from direct measurements using cyclic tests (65.4 ± 2%) agree closely with the estimated latent effectiveness from single-step tests (64.6 ± 2%) at controlled operating conditions. Compared to HAS15- and SG13-coated exchangers, the SP-CPB0.5-coated exchanger performed much better at controlled operating conditions, along with improved longevity due to the CPB surface coating. The presence of CPB did not attenuate the uptake properties of native SPs. Latent effectiveness of SP-CPB0.5-coated exchanger was enhanced (5-30% higher) over that of the SG13- or HAS15-coated exchangers, according to the wheel angular speed. This study reports on a novel and sustainable SP-CPB0.5 material as a promising desiccant coating with tunable uptake and surface properties with potential utility in air-to-air energy exchangers for ventilation systems.

Spectroscopic and Thermodynamic Study of Biopolymer Adsorption Phenomena in Heterogeneous Solid-Liquid Systems.

Molecular selective adsorption processes at the solid surface of biopolymers in mixed solvent systems are poorly understood due to manifold interactions. However, the ability to achieve adsorptive fractionation of liquid mixtures is posited to relate to the role of specific solid-liquid interactions at the adsorbent interface. The hydration of solid biopolymers (amylose, amylopectin, cellulose) in binary aqueous systems is partly governed by the relative solvent binding affinities with the biopolymer surface sites, in accordance with the role of textural and surface chemical properties. While molecular models that account for the surface area and solvent effects provide reliable estimates of hydration energy and binding affinity parameters, spectroscopic and thermal methods offer a facile alternative experimental approach to account for detailed aspects of solvation phenomena at biopolymer interfaces that involve solid-liquid adsorption. In this report, thermal and spectroscopic methods were used to understand the interaction of starch- and cellulose-based materials in water-ethanol (W-E) binary mixtures. Batch adsorption studies in binary W-E mixtures reveal the selective solvent uptake properties by the biomaterials, in agreement with their solvent swelling in pure water or ethanol. The nature, stability of the bound water, and the thermodynamic properties of the biopolymers in variable hydration states were probed via differential scanning calorimetry and Raman spectroscopy. The trends in biopolymer-solvent interactions are corroborated by dye adsorption and scanning electron microscopy, indicating that biopolymer adsorption properties in W-E mixtures strongly depend on the surface area, pore structure, and accessibility of the polar surface groups of the biopolymer systems, in agreement with the solvent-selective uptake results reported herein.

Starch Particles, Energy Harvesting, and the "Goldilocks Effect".

This study reports on the unique water vapor adsorption properties of biomass-derived starch particles (SPs). SPs offer an alternative desiccant for air-to-air energy exchangers in heating, ventilation, and air conditioning systems because of their remarkable adsorption-desorption performance. SP15 has a particle diameter (d p) of 15 µm with a surface area (SA) of 2.89 m2/g and a pore width (P w) of 80 Å. Microporous starch particles (SP15) were compared with high amylose starch (HAS15; SA = 0.56 m2/g, d p = 15 µm, P w = 46 Å) and silica gel (SG13; SA = 478 m2/g, d p = 13 µm, P w = 62 Å). Transient water vapor tests were performed using a customized small-scale energy exchanger coated with SP15, HAS15, and SG13. The water swelling (%) for SP15 was ca. 2 orders of magnitude greater with markedly higher (ca. three- and six-fold) water vapor uptake compared to HAS15 and SG13, respectively. At similar desiccant coating levels on the energy exchanger, the latent effectiveness of the SP15 system was much improved (4-31%) over the HAS15 and SG13 systems at controlled operating conditions. SP15 is a unique desiccant material with high affinity for water vapor and superior adsorption properties where ca. 98% regeneration was achieved under mild conditions. Therefore, SPs display unique adsorption-desorption properties, herein referred to as the "Goldilocks effect". This contribution reports on the utility of SPs as promising desiccant coatings in air-to-air energy exchangers for ventilation systems or as advanced materials for potential water/energy harvesting applications.

Polysaccharide-based materials and their adsorption properties in aqueous solution.

Polysaccharides (PS) of cellulose, soluble, corn- and maize-derived starches with variable amylose/amylopectin content were cross-linked with epichlorohydrin (EPI) to form polymeric adsorbents. The properties of the cross-linked PS-EPI materials were prepared by varying the synthesis conditions (nature of polysaccharide, temperature, and reagent ratios) to afford network polymer materials with tunable properties. The optimized polymers were obtained at a reaction temperature (50-54 °C) according their yield were characterized using spectroscopic (IR and NMR) methods, and thermal gravimetric analysis (TGA). The textural and adsorptive properties of the polymers were evaluated using nitrogen gas and dye-based methods using p-nitrophenol. Solvent uptake, nitrogen adsorption, and aqueous dye sorption show that the amylose and amylopectin content in the PS-EPI copolymers display a complex relationship with their physicochemical properties. Polymers with greater cross-linking did not show incremental changes in water or dye uptake. Structural variation of the polysaccharide (i.e. branching, molecular weight, and relative amylopectin/amylose content) contributed to the sorption properties by modifying their textural properties and surface chemistry.