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Spray-freeze-dried Particles as Novel Delivery Systems for Vaccines and Active Pharmaceutical Ingredients
Published in S. Padma Ishwarya, Spray-Freeze-Drying of Foods and Bioproducts, 2022
Contrarily, increasing the protein (BSA) concentration (2% to 10%) reduced the tendency to aggregate, due to the ‘volume exclusion’ phenomenon of macromolecular crowding. At higher concentration of macromolecules, it is hypothesized that the protein unfolding is suppressed and its overall mobility is reduced due to thermodynamic stabilization (Minton 2005; Ohtake, Kita, & Arakawa, 2011). An auxiliary hypothesis for the same event is that, provided the interface is saturated with protein molecules, then, any further increase in the concentration of protein in bulk will reduce protein aggregation (Arsiccio & Pisano, 2020). This study demonstrated that HPβCD is a competent excipient in the preparation of spray-freeze-dried protein formulations with good aerosol properties (Lo et al., 2021). But, further studies must be extended in this line to come up with more stable and effective protein inhaler powders.
Macromolecular Crowding
Published in Mihai V. Putz, New Frontiers in Nanochemistry, 2020
Adriana Isvoran, Laura Pitulice, Eudald Vilaseca, Isabel Pastor, Sergio Madurga, Francesc Mas
Macromolecular crowding (MC) refers to a high concentration of macromolecules that is present in a limited space such as the intracellular environment. A substantial proportion of the considered volume is physically occupied, reducing the effective volume available for all present molecules. This volume exclusion is a relevant factor in analyzing soft interactions, viscosity, perturbed diffusion and physical interactions between the present molecules and it affects both the properties of molecules and the physicochemical processes taking place in such environment. Crowding especially influences diffusion processes and biochemical reactions with great implications in biochemistry and cell biology.
Efficient synthesis of vitamin A palmitate in nonaqueous medium using self-assembled lipase TLL@apatite hybrid nanoflowers by mimetic biomineralization
Published in Green Chemistry Letters and Reviews, 2018
Liqing Xu, Jianyun Yu, Anming Wang, Chengyi Zuo, Huimin Li, Xinxin Chen, Xiaolin Pei, Pengfei Zhang
Figure 5 shows that appropriate content of water in the aqueous-PE medium is advantageous for the enzymatic synthesis of vitamin A palmitate catalyzed by TLL preparations. When the water content is 20% (V/V), both free TLL and hNFs presented the highest catalytic synthetic activity to yield the vitamin A palmitate. The yield of the target product using hNFs as biocatalyst was 88.3% when the water content was 20%, 2.4 folds of that in full aqueous medium. In our work, calcium phosphate and hydroxyapatite around enzyme in the hNFs are hydrophilic and they might form multiple hydrogen bonds with enzyme protein and mimic the activating effect of water, then loosen up the structure of enzyme and activate enzyme (38) in the alkane solvent of high concentration. In addition, the higher content of PE was more suitable than the lower one for the TLL catalytic hydrolysis in the water-PE system. For the polar solvent such as water, the polarity in the system increased as the elevation of the content and the high polarity would lead to the denaturation of enzyme protein (39, 40). However, the hNFs were supposed to create macromolecular crowding by their nanopores which is usually found in a cell (41, 42), which could accelerate the refolding of enzyme protein (43, 44) and increase the enzymatic activity (45, 46).