Characterization of powdered epidermal vaccine delivery with multiphoton microscopy

Abstract

Multiphoton laser scanning microscopy (MPLSM) has been adapted to non-invasively characterize hand-held powdered epidermal vaccine delivery technology. A near infrared femtosecond pulsed laser, wavelength at approximately 920 nm, was used to evoke autofluorescence of endogenous fluorophores within ex vivo porcine and human skin. Consequently, sub cellular resolution three-dimensional images of stratum corneum and viable epidermal cells were acquired and utilized to observe the morphological deformation of these cells as a result of micro-particle penetration. Furthermore, the distributional pattern of micro-particles within the specific skin target volume was quantified by measuring the penetration depth as revealed by serial optical sections in the axial plane obtained with MPLSM. Additionally, endogenous fluorescence contrast images acquired at the supra-basal layer reveal cellular structures that may pertain to dendritic Langerhans cells of the epidermis. These results show that MPLSM has advantages over conventional histological approaches, since three-dimensional functional images with sub-cellular spatial resolution to depths beyond the epidermis can be acquired non-invasively. Accordingly, we propose that MPLSM is ideal for investigations of powdered epidermal vaccine delivery.

Synthesis of (S)-(+)-2-methyl-4-octanol: male-specific compound released by sugarcane weevil Sphenophorus levis (coleoptera: curculionidae)

“…The freshly distilled aldehyde 4 was subjected to the Wittig reaction with (triphenylphosphonium)propanide (CH 3 CH 2 CH=PPH 3 ) 11 to give compound 5 in 88% yield [it was observed that the (Z)-isomer was preferentially obtained , as indicated by 1 H-NMR data]. Hydrogenation over Pd/C furnished compound 6 (81% yield), which was hydrolyzed 12 under acidic Dowex ® resin (W50) yielding diol 7 in 79% yield. This diol 7 was converted into the mono tosylate 8 in 60% yield, by reaction with TsCl in pyridine, and then coupled with sec-propyl magnesium bromide, using CuI as catalyst, 3 affording the desired alcohol 1 in 78% yield.…”

Utilization of the venturi effect to introduce micro-particles for epidermal vaccination

“…A few alternative designs have been proposed [8][9][10]. In Oxford University, we have been developing a controllable hand-held powdered injection system (biolistic), which harnesses the energy of compressed helium gas to accelerate micron-sized powdered vaccines to a sufficient momentum to penetrate the outer layer of skin or mucosal tissue to target the cells of interest [14][15][16][17][18][19][20][21][22]. Fig.…”

Numerical analysis of gas and micro-particle interactions in a hand-held shock-tube device

“…Since, these uniquely quantified clinical CST devices have been applied to a range of studies exploring the fundamentals of ballistic impact of micro-particles to human skin ; porcine skin Mulholland et al, 2004) and canine mucosa (Mitchell et al, 2003). The induced biological responses are also being interrogated (Mulholland et al, 2004;Raju et al, 2006), and this work is ongoing.…”

“…The induced biological responses are also being interrogated (Mulholland et al, 2004;Raju et al, 2006), and this work is ongoing. With these CST clinical devices so broadly utilized in important biolistic applications, there is a need to extend the understanding of the gas and particle dynamics of these systems beyond the reported analytical and experimental studies (Kendall, 2002;Truong, 2005).…”