Shape Effect in the Design of Nanowire-Coated Microparticles as Transepithelial Drug Delivery Devices

While the oral drug delivery route has traditionally been the most popular among patients, it is estimated that 90% of therapeutic compounds possess oral bioavailability limitations. Thus, the development of novel drug carriers for more effective oral delivery of therapeutics is an important goal. Composite particles made by growing nanoscopic silicon wires from the surface of narrowly dispersed, microsized silica beads were previously shown to be able to (a) adhere well onto the epithelium by interdigitating their nanowires with the apical microvilli and (b) increase the permeability of Caco-2 cell monolayers with respect to small organic molecules in direct proportion to their concentration. A comparison between the effects of spherical and planar particle morphologies on the permeability of the epithelial cell layer <i>in vitro</i> and <i>in vivo</i> presented the subject of this study. Owing to their larger surface area, the planar particles exhibited a higher drug-loading efficiency than their spherical counterparts, while simultaneously increasing the transepithelial permeation of a moderately sized model drug, insulin. The insulin elution profile for planar nanowire-coated particles displayed a continual increase in the cumulative amount of the released drug, approaching a constant release rate for a 1–4 h period of the elution time. An immunohistochemical study confirmed the ability of planar silica particles coated with nanowires to loosen the tight junction of the epithelial cells to a greater extent than the spherical particles did, thus, enabling a more facile transport of the drug across the epithelium. Transepithelial permeability tests conducted for model drugs ranging in size from 0.4 to 150 kDa yielded three categories of molecules depending on their permeation propensities. Insulin belonged to the category of molecules deliverable across the epithelium only with the assistance of nanowire-coated particles. Other groups of drugs, smaller and bigger, respectively, either did not need the carrier to permeate the epithelium or were not able to cross it even with the support from the nanowire-coated particles. Bioavailability of insulin orally administered to rabbits was also found to be increased when delivered in conjunction with the nanowire-coated planar particles

Body mass and composition in rapamycin-fed mice (filled circles) versus controls (hollow circles).

<p>P-values shown on individual panels only if there is a significant treatment effect independent of age. Sample sizes varied, depending on age, control females, n = 32–2; rapamycin females, n = 30–4; control males, n = 33–2; rapamycin males, n = 36–3. <b>A, B: Total body mass.</b> Highly significant differences (p << 0.001) exist in treatment x age effects in body for both sexes. Although they weighed less than controls by 16 months of age, rapamycin-fed females retained body mass longer, whereas rapamycin-fed males were similar to controls at 16 months but lost body mass earlier and remained lighter as they aged. <b>C, D: Percent body fat.</b> Highly significant differences (p << 0.001) in treatment x age effects exist for both sexes. As in with body mass, aging rapamycin-fed females retained body fat longer and lost body fat more slowly than age-matched controls. In contrast, rapamycin-fed males initially had a higher percentage of body fat, but lost fat mass earlier than controls. <b>E, F: Fat-free mass,</b> sometimes referred to as lean mass. Although obscured by the scaling, rapamycin-fed females had lower fat-free mass than controls at all ages measured. Fat-free mass declined more slowly with age in rapamycin-fed females than males.</p

Body mass and composition in rapamycin-fed mice (filled circles) versus controls (hollow circles).

<p>P-values shown on individual panels only if there is a significant treatment effect independent of age. Sample sizes varied, depending on age, control females, n = 32–2; rapamycin females, n = 30–4; control males, n = 33–2; rapamycin males, n = 36–3. <b>A, B: Total body mass.</b> Highly significant differences (p << 0.001) exist in treatment x age effects in body for both sexes. Although they weighed less than controls by 16 months of age, rapamycin-fed females retained body mass longer, whereas rapamycin-fed males were similar to controls at 16 months but lost body mass earlier and remained lighter as they aged. <b>C, D: Percent body fat.</b> Highly significant differences (p << 0.001) in treatment x age effects exist for both sexes. As in with body mass, aging rapamycin-fed females retained body fat longer and lost body fat more slowly than age-matched controls. In contrast, rapamycin-fed males initially had a higher percentage of body fat, but lost fat mass earlier than controls. <b>E, F: Fat-free mass,</b> sometimes referred to as lean mass. Although obscured by the scaling, rapamycin-fed females had lower fat-free mass than controls at all ages measured. Fat-free mass declined more slowly with age in rapamycin-fed females than males.</p

Age-related changes in inner ear histology was not altered by rapamycin treatment.

<p><b>A, B: The number of cochlear neurons</b> in male and female mice were not statistically different between control and rapamycin-fed animals. <b>C,D: The number of outer hair cells</b> in male and female mice were not statistically different between control and rapamycin-fed animals. <b>E,F: The number of inner hair cells</b> in male and female mice were not statistically different between control and rapamycin-fed animals.</p

Rapamycin concentration in whole blood at 10 months of age (after 6 months of rapamycin feeding).

<p>Blood concentrations of rapamycin were significantly higher in females than males after 6 months of rapamycin feeding (n = 18 and 14 respectively).</p

Strength, coordination and movement in rapamycin-fed mice (filled circles) compared to controls (hollow circles).

<p>P-values shown on individual panels only if there is a significant treatment effect independent of age. <b>A, B: Grip strength</b> declined significantly with age in all animals, regardless of treatment (p << 0.001); however rapamycin treatment affected males and females differently (treatment x sex, p = 0.003). Rapamycin-fed females had greater grip strength than controls at all ages measured; whereas grip strength in control and rapamycin treated males did not differ. Sample sizes varied, depending on age, control females, n = 17–7; rapamycin females, n = 27–4; control males, n = 22–4; rapamycin males, n = 31–3. <b>C, D: Stride length</b> increased in males and females until 27 months of age and then declined with increasing age (p << 0.001). Rapamycin treatment had no effect on stride length in either sex. Sample sizes varied, depending on age, control females, n = 15–6; rapamycin females, n = 21–5; control males, n = 19–4; rapamycin males, n = 26–9. <b>E, F: Rotarod performance,</b> measured as maximum latency to fall, was significantly affected by body mass (p << 0.001) and so body mass was included as a covariate in the analysis. With the effects of body size removed, females showed no effects of rapamycin treatment and males showed a marginally significant negative effect of rapamycin treatment on rotarod performance. The y-axis shows the residuals of rotarod performance (latency to fall) regressed against body mass. Sample sizes varied, depending on age, control females, n = 11–6; rapamycin females, n = 19–6; control males, n = 13–7; rapamycin males, n = 21–8.</p

Differences in two rapamycin studies.

<p>↑ Increased ↓ Decreased, ↑↓ Maintained with age,—No difference from controls</p><p>*p < 0.05</p><p>** p < 0.01</p><p>*** p < 0.001</p><p>^§ Treatment X Age effect</p><p>Healthspan measures: young-fed measured between ages 16 and 29 months; old-fed measured at 25, 31 and 32 months.</p><p>Young-fed mice (rapamycin feeding begun at 4 mo, this study) compared with old-fed (rapamycin feeding begun at 19 mo) [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0126644#pone.0126644.ref011" target="_blank">11</a>].</p><p>Differences in two rapamycin studies.</p

Metabolic activity in rapamycin-fed mice (filled circles) compared to controls (hollow circles).

<p>P-values shown on individual panels only if there is a significant treatment effect independent of age. Sample sizes varied, depending on age, control females, n = 8–4; rapamycin females, n = 11–3; control males, n = 9–5; rapamycin males, n = 16–2. <b>A, B: Mass-specific metabolic rate during the light (= inactive) phase.</b> Males and females showed no effects of rapamycin treatment on mass-specific metabolic rate during the inactive phase of their daily 24-hour cycle, although both sexes showed highly significant (p << 0.001) sex x age treatment effects. <b>C, D: Mass-specific metabolic rate during the dark (= active) phase.</b> Aging rapamycin-fed females, but not males, maintained significantly higher metabolic rates between measures taken at 24 and 28 months of age compared to controls during the dark (= active) phase of the 24-hour light cycle. Both males and females showed highly significant (p <<0.001) decline dark-phase metabolic rate with age irrespective of treatment. <b>E, F: Resting mass-specific metabolic rate.</b> Resting metabolic rate declined with age in females, but aging rapamycin-fed females had higher resting metabolic rates compared to age-matched controls. Resting metabolic rate declined significantly in aging rapamycin-fed males but not in age-matched controls (treatment x age, p << 0.001).</p

Nanostructure-Mediated Transport of Biologics across Epithelial Tissue: Enhancing Permeability via Nanotopography

Herein, we demonstrate that nanotopographical cues can be utilized to enable biologics >66 kDa to be transported across epithelial monolayers. When placed in contact with epithelial monolayers, nanostructured thin films loosen the epithelial barrier and allow for significantly increased transport of FITC-albumin, FITC-IgG, and a model therapeutic, etanercept. Our work highlights the potential to use drug delivery systems which incorporate nanotopography to increase the transport of biologics across epithelial tissue