Nanosuspensions as Nanomedicine: Current Status and Future Prospects
Debarshi Kar Mahapatra, Sanjay Kumar Bharti in Medicinal Chemistry with Pharmaceutical Product Development, 2019
Nanosuspension solidification can also be achieved using other established methods, such as freeze-drying [80]. Freeze-drying is the most suitable approach for the solidification of thermolabile drugs, such as protein drugs and vaccines [140]. Freeze-drying is also commonly used to retain the redispersibility of drug nanoparticles after solidification. Freezing rate and the type of cryoprotectants are two critical factors in the freeze-drying process. A cryoprotectant is usually added to the freshly prepared nanosuspensions to avoid freeze damage due to ice formation and to avoid particle aggregation [141]. A series of polymer cryoprotectants, such as polyatomic alcohols, are usually selected to stabilize nanosuspensions during the freeze-drying process. The most frequently used polyatomic alcohols include mannitol, lactose, sucrose, trehalose, and glucose.
Synthetic Seeds Vis-A-Vis Cryopreservation: An Efficient Technique for Long-Term Preservation of Endangered Medicinal Plants
Amit Baran Sharangi, K. V. Peter in Medicinal Plants, 2023
On the contrary, cryopreservation is the most widely used method for long-term storage of germplasm under ex-situ condition at ultra-low temperature (–150 to –196°C) using liquid nitrogen (Chudhury and Malik, 2004). This is the only method to ensure the safe and cost-efficient long-term conservation of various types of plants (Engelmann, 2011). This method has been widely used for long time conservation because the metabolic activity of cells, cell divisions are ceased at an ultra-low temperature as well as there is no scope of any genetic modification which may happen during when they are maintained by serial subculturing (Cruz-Cruz et al., 2013). Optimum responses of plant propagules after cryopreservation are depending on the status of the plant, cryopreservation techniques and re-growth conditions (Uchendu and Reed, 2008). A convenient way of cryopreservation leads to the formation of ice and increases the solute concentration within the cell which causes cell damage. To counter this problem, cryoprotectants are used to reduce the amount of ice that crystallizes at any given temperature and thereby limit the solute concentration factor (Fahy et al., 1984).
Quality Control in Bone Marrow Processing
Adrian P. Gee in BONE MARROW PROCESSING and PURGING, 2020
The most widely used cryoprotectant is dimethyl sulfoxide (DMSO), although it has not been formally approved by the FDA for this application (see Chapter 2). Adverse reactions to this agent can occur,5 particularly when large volumes are infused, e.g., in the case of peripheral blood stem cell transplants. Alternative freezing mixtures, in which the concentration of DMSO is reduced, have been developed (as described in this volume) and should be investigated where possible. The other components of the mixture consist of tissue culture medium and a protein source. Again, questions relating to the use of cell culture medium raised earlier in this article should be borne in mind. In particular, it is advisable to use indicator-free preparations, since there have been reports of adverse reactions to phenol red in transplant recipients.
In vivo biodistribution of venlafaxine-PLGA nanoparticles for brain delivery: plain vs. functionalized nanoparticles
Published in Expert Opinion on Drug Delivery, 2019
M.D. Cayero-Otero, Maria João Gomes, Cláudia Martins, J. Álvarez-Fuentes, M. Fernández-Arévalo, B. Sarmento, L. Martín-Banderas
Lyophilization is a process that involve three differentiated stages: (i) first stage consists of the freezing of aqueous suspension of NPs which is the most determinant for the quality of biopharmaceutics; (ii) next, the primary drying step involves the sublimation of the ice from frozen product. After complete sublimation, pores are formed that correspond to the sites of ice previously; (iii) finally, the water absorbed by the product is eliminated in a secondary drying. It is a slow and expensive technique, widely used to improve the stability of various pharmaceutical actives [42]. Freezing is an aggressive process for NPs, so the use of a cryoprotectant is essential to ensure the final quality of the product (Abdelwahed et al., 2006). The most commonly used criprotectors are: low molecular weight alcohols such as polyethylene glycol or sugars such as mannitol, trehalose or sucrose (Almalik et al., 2017).
Successful application of a single warming protocol for embryos cryopreserved by either slow freezing or vitrification techniques
Published in Systems Biology in Reproductive Medicine, 2019
Munevver Serdarogullari, Onder Coban, Fazilet Kubra Boynukalin, Ekrem Murat Bilgin, Necati Findikli, Mustafa Bahceci
For these reasons, having a universal warming protocol that can be successfully used in such cases would bring a very important contribution and help in routine cryopreservation/warming practice. Although there are major differences in terms of nature, concentration, as well as the behavior of the cryoprotectants between slow freezing and vitrification approaches, the end point, which is the conversion to a solid state without ice crystal formation, is the same (Fahy et al. 1987). During thawing or warming processes, the use of extracellular (non-permeable) cryoprotectants is used to create a gradient. This stepwise decrease in concentration of these molecules can thereby create a controlled rehydration. Furthermore, using higher concentrations of cryoprotectants during warming is necessary to avoid ice crystal formation during warming (Vanderzwalmen et al. 2012).
Optimization of composite cryoprotectant for freeze-drying Bifidobacterium bifidum BB01 by response surface methodology
Published in Artificial Cells, Nanomedicine, and Biotechnology, 2019
He Chen, Mengqi Tian, Li Chen, Xiuxiu Cui, Jiangpeng Meng, Guowei Shu
The addition of cryoprotectants can reduce cell damage and cell death rate [21]. Single protective agent is not enough to protect the B. bifidum effectively; therefore, complex protective agents are required to improve the bacterial survival rate. It has been reported that 10 or 20% polysaccharide mixed with 10% skim milk exhibits the best protective effect against Bifidobacterium MYL16 [22]. Generally, the formulation of the protective agent depends on the cell structure. Response surface methodology (RSM) can be used to design, optimize and improve the protective agent combination which is time-saving and low cost [23,24]. Center composite design (CCD) is appropriate to study factors with three and/or five levels. The obtained results could fit with a nonlinear mathematical model and the equation expresses the relationship between the independent factors and the response values. The response values finally show the optimized cryoprotectant combination [25].
Related Knowledge Centers
- Antifreeze Protein
- Cryobiology
- Cryogenics
- Glycerol
- Tissue
- Xenobiotic
- Freezing
- Antifreeze
- Liquid Nitrogen
- Organ Transplantation