Emulsions and microemulsions with a fluorocarbon phase
Introduction
Emulsions with a fluorocarbon (or perfluorocarbon, PFC; perfluoroalkyl=F-alkyl; for the extended use of the F- and, by analogy, for the H-symbols, see [1]) phase are being investigated, essentially for their potential biomedical applications. Three main lines of research are being actively pursued: emulsions for in vivo oxygen delivery (blood substitutes); targeted emulsions for diagnosis and therapy; and water-in-PFC reverse emulsions for pulmonary drug delivery. Microemulsions with PFC phases or fluorosurfactants, including water-in-supercritical CO2 microemulsions, are being used in polymerization technology and provide valuable research tools.
Section snippets
Fluorocarbon-in-water emulsions—injectable oxygen carriers
The reasons for, basic concepts, industrial development, ‘physiology’ and clinical investigation of PFC emulsions destined to serve as in vivo oxygen carriers have recently been reviewed and discussed in some length [2]••[3]. Basic properties of PFCs can be found in Ref. [4], details on emulsion engineering in Ref. [5], an update on clinical trial status in Ref. [6]•• and a report on PFC blood substitute research in Russia in Ref. [7]; a review of the biomedical applications of fluorinated
Targeted fluorocarbon emulsions
Targeted PFC emulsions are being investigated for the purpose of molecular imaging, i.e. detection of molecular markers, such as proteins and other cell-surface receptors, characteristic of a given pathology; such emulsions have also potential for site-directed drug delivery [41]••. Important potential target pathologies include inflammation, atherosclerosis, tumor-related angiogenesis and thrombi. Detection and differentiation from normal tissue involves binding ligands specific for epitopes
Reverse water-in-fluorocarbon emulsions
Producing stable water-in-PFC emulsions was not a trivial challenge, since PFCs are extremely hydrophobic. Such emulsions were nevertheless obtained using strongly fluorophilic, weakly hydrophilic amphiphiles, namely F-alkyl dimorpholinophosphates, CnF2n+1CmH2mOP(O)[N(CH2CH2)2O]2 [51]. A range of new compositions has now been reported, including macro-, mini- and microemulsions [52]•. These emulsions have potential for use as pulmonary drug delivery systems [53]. Investigation of mixed
Microemulsions with highly fluorinated components
F-microemulsions represent approximately 10% of the literature on microemulsions and share numerous features, constraints and perspectives with standard non-fluorinated microemulsions [58]. F-microemulsions are defined as thermodynamically stable isotropic liquids containing domains of tens of nanometers, stabilized by an interfacial amphiphilic film. At least two mutually insoluble liquids and a surfactant are involved in the spontaneous formation of either droplets or bicontinuous
Summary and prospects
PFC-in-water emulsions have been demonstrated to dissolve, transport and deliver O2 in surgery. F-octyl bromide appears to be the best candidate PFC for this purpose and Oxygent™ is a well-designed, stable emulsion. Although extensive investigation found no evidence of any adverse effects of the emulsion, the suspension of a cardiopulmonary bypass trial with Oxygent™, most likely because of an inadequate protocol, is slowing down the development of injectable PFC-based O2 carriers. Protocol
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2022, Journal of Cleaner ProductionCitation Excerpt :Moreover, surface activity of these perfluorinated and polyfluorinated surfactants have enhanced efficiency and effectivity in comparison to their H-counterparts’ surfactants. Therefore, surface tensions can be lowered even while using reduced quantities of these surfactants (Syed et al., 2021; Krafft et al., 2003). The first objective of the current work is to formulate nano-sized emulsions (Zavg ≤ 150 nm), with a monomodal narrow-sized droplet distribution, consisting of PFD as the dispersed phase and water with surfactant(s) as the continuous phase.
Therapeutic oxygen delivery by perfluorocarbon-based colloids
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2021, Colloids and Surfaces A: Physicochemical and Engineering AspectsCitation Excerpt :Amongst already existing literature on the production of PFC-based emulsions in the micro-scale, there are several works that have used PFC-based microemulsions for liquid ventilation, oxygen delivery, and diagnosis [3,5,13]. However, there are still pivotal issues concerning this type of systems at the micro-scale, which have limited their efficiency, approval, and commercial success, namely those related to emulsion droplet size (and size distribution), and emulsion stability [2,14]. Additionally, the potential toxicity, harmful side effects and clearance/excretion issues associated to the employed surfactant/co-surfactant systems may also be a relevant issue for most parenteral therapeutic and biomedical applications [15–18].
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2020, Current Opinion in Colloid and Interface ScienceEmulsions of fluorinated oils stabilised by fluorinated silica nanoparticles
2016, Colloids and Surfaces A: Physicochemical and Engineering AspectsCitation Excerpt :Recently, emulsions containing fluorinated oil have been used successfully for the controlled delivery of inhalational anaesthetics [5–7] and in the formulation of poorly water-soluble drugs [8]. Over the last decades, extensive research studies have been carried out to formulate stable FC emulsions using different stabilisers [9,10]. FC emulsions have been stabilised using nonionic fluorosurfactants such as Zonyls FSN-100 and FSO-100 [11,12] and polymeric non-fluorinated surfactants such as Pluronic F-68 [13,14] and Proxanol-268 [15].
Evaluation of pharmacokinetic properties and anaesthetic effects of propofol in a new perfluorohexyloctane (F6H8) emulsion in rats - A comparative study
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