China
Africa
Explore chapters and articles related to this topic
Vaccine Development Strategies and the Current Status of COVID-19 Vaccines
Published in Debmalya Barh, Kenneth Lundstrom, COVID-19, 2022
Mohsen Akbarian, Kenneth Lundstrom, Elrashdy M. Redwan, Vladimir N. Uversky
In addition to alum, emulsion adjuvants have also been successful in formulating vaccines. For example, AS03 and AS03 emulsion adjuvants are used to increase the immunogenicity of antigens in human vaccines. Compared to alum, AS03 and AS03 emulsion may result in more appropriate responses, probably by recruiting immune cells, improving antigen uptake, and promoting activation of antigen-presenting cells (APCs) [13, 14]. In the case of CoV vaccines, emulsion adjuvants have been used at the pre-clinical level. For example, MF59 has been used in inactivated SARS and MERS vaccines and/or RBD vaccines for MERS-CoV. Emulsions such as MF59-like and alum stabilized Pickering emulsion (PAPE) have also been used to enhance the immune response of protein subunit vaccines against SARS-CoV-2 [8].
Novel Starch-Derived Topical Delivery Systems
Published in Andreia Ascenso, Sandra Simões, Helena Ribeiro, Carrier-Mediated Dermal Delivery, 2017
Joana Marto, Inês Jorge, Antonio de Almeida, Helena Ribeiro
The versatility of starch for stabilizing emulsion can be seen in the study performed by Matos et al. [17], where OSA was also used in the development of a double w/o/w (water-in-oil- in-water) Pickering emulsion. To the inner water phase was added sodium chloride (NaCl) and the continuous oil phase consisted of Miglyol® 812 and of a lipophilic surfactant: polyglycerol polyricinoleate 90 (PGPR 90). In the outer aqueous phase was added a sodium phosphate buffer, since it has showed to enhance the oil droplets separation. With the addition of PGPR 90, a decreased mean droplet size was possible to obtain and a higher viscosity of the oil phase, which resulted in a less pronounced sedimentation of the inner aqueous phase. This double emulsion showed high encapsulation efficiency (around 98.6%) and high encapsulation stability (91.1-95.2% after 3 weeks of study), confirming the high chemical stability of this double Pickering emulsion.
Microencapsulation of reactive isocyanates for application in self-healing materials: a review
Published in Journal of Microencapsulation, 2021
Amanda N. B. Santos, Demetrio J. dos Santos, Danilo J. Carastan
Another interesting approach to microcapsule production involves the formation of a Pickering emulsion, in which solid particles have a direct role in stabilising the emulsion. Several solid particulated materials can be used in this kind of application, such as colloidal silica (Frelichowska et al.2009), clay nanoparticles (Chakrabarty et al.2016) and even organic materials, such as cellulose nanostructures and lignin (Bai et al.2018). Lignin is an abundant natural polymer with a complex phenolic structure, which has been increasingly applied into polymer systems to improve their thermal and mechanical properties (Tavares et al.2016, Gouveia et al.2019a, 2019b). It is usually obtained in the form of solid microparticles, which can form stable dispersions/solutions in aqueous medium within a certain pH range; lignin particles can therefore act as Pickering emulsion stabilisers, due to their ability to form solid barriers by being adsorbed at the emulsion interface. Yi et al. (2015) successfully encapsulated an isocyanate by using lignin as a Pickering emulsion stabiliser. Lignin particles were then incorporated into the shell structure to optimise its properties, by enhancing microcapsule strength and preventing isocyanate degradation. Lignin was added into water, and the pH adjusted to 10–11, permitting lignin dispersion. As the next step, pH was lowered to 2–3, leading to lignin precipitation and particle formation. The Pickering emulsion was obtained by dispersing the oil phase (mixture of IPDI and MDI) into lignin particle solution. An aqueous solution of polyvinyl alcohol (PVA), acting as a surfactant, was prepared separately. Then melamine-formaldehyde pre-polymer (pre-MF), synthesised in laboratory, was added into the PVA solution followed by pH adjustment to 2–3. Under mechanical agitation, the Pickering emulsion was added into the reaction system. (Yi et al.2015). Figure 5 illustrates the synthesis procedure.
Janus nanoparticles: an efficient intelligent modern nanostructure for eradicating cancer
Published in Drug Metabolism Reviews, 2021
Farshid Gheisari, Mostafa Shafiee, Milad Abbasi, Ali Jangjou, Peyman Izadpanah, Ahmad Vaez, Ali Mohammad Amani
The preservation is one aspect of the nanoparticle surface layer whereby the covered layer becomes unavailable for chemicals and polymerization, modifications, functionalization, or some other chemical processes. These are performed upon the unsupervised part throughout the nanostructure, deemed as the masking process (Song 2018). While trigger particulates are partly caught by the template, patchy particles can indeed be acquired. However, if half of such targeting particles shield, JPs can be attained. In many instances, asymmetrical functionalization of the particulates and nanomaterials is performed by either preserving a section of the particle surface through capturing the particulates upon a solid substrate or even at the boundary of two states. This means that only the visible area of each particle is accessible for chemical functionalization (Poggi and Gohy 2017). There have been two approaches to the masking procedure. One of these is a solid substrate masking process through evaporative single-crystal polymer templating, electrostatic adsorption, and deposition pattern. Another is the suspension of nanomaterials at the interface between two liquid phases, including the Pickering emulsion process. Moreover, the Pickering emulsion frequently provides a technique for phase separation. The masking method by binding the particulate matter to a solid surface through a masking process can be commonly implemented to sizeable particles which are less acceptable to utilize far smaller nanostructure. This is in contrast to the fact that Pickering emulsion is effective in the development of tiny JNPs. A significant variety of techniques for the preparation of JNPs utilizes several variations of the masking procedure. It implies that the asymmetrical modifications of nanostructures are accomplished by introducing only one portion (or, in particular, a part) of one’s surface to an area under which an interaction becomes performed (Song 2018). Nonetheless, the remaining portion of the layer is shielded. Usually, the masking procedure has been performed through caging nanomaterials at the phase boundary of liquid or through depositing and solubilized particles on a solid layer. Masking is possibly the most adaptable among all of the methodologies used to develop JNPs because it is appropriate to practically any kind of substance. It can also provide the potentiality of modifying the surface areas of nanomaterials by a broad range of functional groups (Kirillova 2019). Since this surface modification of particulates accumulated on clear solid material gives the fullest variety of surface modification possibilities, there are also major problems with scalability. Otherwise, by the application of distributed phases of particulates and tiny particles to have a (greater) surface area, nanostructures and nanocrystals can indeed be captured. It appears to be a suitable option for producing greater amounts of JNPs but restricts the number of surface modifications that can be implemented. By means of advances throughout our knowledge of Pickering emulsions production, regulated by nanoparticles, greater amounts of JNPs are anticipated to become accessible (Yang and Loos 2017a).