General and Practical Aspects of Membrane Protein Crystallization
Hartmut Michel in Crystallization of Membrane Proteins, 1991
Molecular sieve chromatography is less powerful for membrane proteins than for soluble proteins, since the detergent-protein complexes are separated as a function of the sum of the molecular weights of bound detergents plus protein. Therefore, it is of advantage to use detergents which form micelles with a small micellar weight. Then the molecular weight of the protein dominates the weight of the complex. Especially suited as detergent seem to be CHAPS (micellar weight: 615035), octyl-β-d-glucopyranoside (micellar weight: 800036) and N, N-dimethyldodecylamine-N-oxide (micellar weight: 16,00037) as compared to Triton X-100 (micellar weight: 90,00030). Molecular sieve chromatography also removes lipids very efficiently, when stronger detergents are used.
Monoterpenes-Based Pharmaceuticals: A Review of Applications In Human Health and Drug Delivery Systems
Megh R. Goyal, Durgesh Nandini Chauhan in Plant- and Marine-Based Phytochemicals for Human Health, 2018
Acidic titanium dioxide (TiO) mesoporous molecular sieves134 or praseodymium-incorporated aluminophosphate molecular sieves (PrAlPO-5)130, 142, 143 are some of the catalysts used in α-pinene isomerization reaction due to their capacity to create acid sites (Lewis or Brӧnsted acid sites) and shape selectivity.27, 130, 134 Moreover, α-pinene oxide can also undergo isomerization in order to produce trans-carveol, trans-sobrerol, and campholenic aldehyde.130 Successively, campholenic aldehyde is one of the main components required to produce santalol (sandalwood fragrance).96, 130 α-terpineol has a distinctive lilac odor and is one of the many products of α-pinene hydration.27
Engineering Stable Spray-Dried Biologic Powder for Inhalation
Anthony J. Hickey, Sandro R.P. da Rocha in Pharmaceutical Inhalation Aerosol Technology, 2019
In preliminary stability testing, representative simulated packaging may be used. It is often overlooked that bottles, vials, and bags are semipermeable to water vapor [311] and should not be used on their own to package spray dried biologics, as high relative humidity storage can inactivate biologics in spray dried powder [128]. Thus, for preliminary stability measurements, spray dried powder can be packaged with desiccant, which is designed to act like a moisture buffer that slows down the effects of moisture ingress; this is due to the large internal surface area of the desiccant to which water can adsorb [316]. Molecular sieve desiccant possesses a high moisture sorption capacity at low relative humidity, whereas silica gel desiccant is useful for protection from higher relative humidity because of a more linear relationship between moisture sorption capacity and relative humidity [317]. Larger quantities of dry desiccant or powder will lower the relative humidity in the container through larger moisture sorption capacity [317].
Alternative method to improve the ethyl valerate yield using an immobilised Burkholderia cepacia lipase
Published in Journal of Microencapsulation, 2019
Wellington Correa Moreira, Alfredo Luís Pereira Elias, Wislei Riuper Osório, Giovana Silva Padilha
Other investigations have also reported that the ester yields are improved when the biocatalysts and solvents water-free are used (Koller et al. 2001, Ghamgui et al. 2006). As a second step, the ethyl valerate yield was performed without the molecular sieve in the reaction mixture. With this, the beads agglomerations are observed. Since the alginate is soluble in water, i.e. hydrophilic material, the by-product water increases the agglomerate formation and a decreasing in the esterification yield is provided. It is well known that into an enzymatic esterification the by-product water should be controlled in order to the esters hydrolysis be prevented. In this case, the use of the molecular sieve, as adopted in this work seems to imply an essential role in order to increase of the ester yields. Horchani et al. (2012) have studied the effect of the molecular sieve in the riccoleic acid yield using an immobilised lipase from Staphylococcus xylosus. The reaction using 0.2 to 1g of the molecular sieve was used. An increasing in the ester yield using molecular sieve was reached. The maximum yield (65 ± 4%) with 1g of the molecular sieve was attained.
Supercritical CO2 versus water as an antisolvent in the crystallization process to enhance dissolution rate of curcumin
Published in Pharmaceutical Development and Technology, 2022
Fatemeh Sadeghi, Hossein Kamali, Sepideh Kouhestanian, Farzin Hadizadeh, Ali Nokhodchi, Hadi Afrasiabi Garekani
The instrument design for the antisolvent crystallization using the supercritical procedure employed in this study was similar to previously reported studies (Figure 1) (Campardelli et al. 2015; Johannsen and Brunner 2018). Initially, the CO2 (compressed in a cylinder), was introduced into a molecular sieve-filled column and then filtered for its purity enhancement. Then the CO2 was liquefied using a recirculation cooling bath. The supercritical conversion of the pumped liquefied CO2 was conducted using a heating step.
Lymphatic targeting for therapeutic application using nanoparticulate systems
Published in Journal of Drug Targeting, 2022
Nidhi Singh, Mayank Handa, Vanshikha Singh, Prashant Kesharwani, Rahul Shukla
The particle size of the nanocarrier serves a vital role in lymphatic uptake. Size controls the nanoparticle biodistribution and reaction with an immune cell after it is administered in the body. The physicochemical properties of nanoparticles pertaining to particle size can be controlled by changing in the method of preparation or the material used in the synthesis of the same [32]. From past decades colloidal based drug delivery systems, metallic nanoparticles, self-assembling systems, dendrimers have gain lot of importance for the nano targeting. Furthermore, these advanced delivery systems can be customised which is an additional advantage and enables the preparation of nanoparticles with desired size by slight modification in the method of preparation. Reddy and co-workers compared the intradermal uptake of nanoparticles with particle size less than 50 and 100 nm in a preclinical animal model. After the intradermal administration, it was observed that polypropylene sulphide stabilised nanoparticles with PEG and poloxamer, of the size range of 50 nm were more rapidly up taken by immature dendritic cells via connective lymphatic drainage in comparison to similar 100 nm sized nanoparticles. Hisataka and co-workers visualised the permeation of Gadolinium labelled dendritic carriers in the lymphatics. They prepared Gadolinium labelled dendritic carriers with diameter size range of less than 12 nm. In preclinical evaluation, they found that particles with diameter of 8 nm or above were able to permeate lymphatics. However, particles with diameter of less than 8 nm were preferentially drained out in the blood vessels via endothelial capillaries. Nanoparticles with size of 8 nm were able to reach collecting lumen vessels through the mechanism of traverse and convection followed by negative charge on extracellular matrix via surface charge and size dependent fashion. The size sieving starts very initially at the interstitial extracellular matrix. This interstitial extracellular matrix acts as molecular sieve for connective tissue because of the formation of water pores that are in size range of 100 nm diameter. Nanoparticles with diameter of 100 nm size get retained at the injection site until they get internalised by dermal or epidermal dendritic cell to lymphatics. However, researchers have reported about intra-lymph node injection that bypasses the size and physicochemical properties of carriers and direct the molecules to lymphatics. Furthermore, for targeting lymph nodes, size requirements might differs depending on the indirect targeting via Antigen presenting cells (APCs), or direct targeting to lymph node. The sieving of particles that enters lymph node is based on hydrodynamic diameter pertaining to the presence of subcapsular sinus. In addition to this, macromolecules with size of more than 70 kDa are transferred to subcapsular sinus and drained from the lymph node through efferent lymphatic system. These large nanoparticles are not selected by immune cells unless and until coated with any complement system. However, macromolecules with size less than 70 kDa are readily uptake by reticular pathway and penetrate deep into paracortical zone.
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