7 research outputs found
Microneedle Integrated Transdermal Patch for Fast Onset and Sustained Delivery of Lidocaine
Lidocaine as an analgesic is of particular
interest in both acute
and chronic pain conditions and is used via injections or transdermal
patches. While injections are associated with problems such as patient
incompliance, topical administration of lidocaine using patches is
less efficient due to variability of drug absorption among individuals,
slower drug permeation through the skin, and hence a resultant undesirable
delay in analgesic effects. To address this clinical problem, we developed
a microneedle integrated transdermal patch (MITP), using a photolithography
based process, in which microneedles create micrometer-sized channels
in the skin to deliver lidocaine rapidly, while the reservoir patch
holding the bulk of the drug enables higher drug loading and carries
on to release the drug for prolonged periods. We demonstrated a new
approach of drug delivery using microneedles, where drugs diffuse
out of microneedles through the porous channels left by dissolving
drug particles. MITP was shown to be able to encapsulate up to 70
mg of lidocaine. <i>In vitro</i> permeation through rat
skin demonstrated that MITP delivered a significantly higher amount
of lidocaine than a commercial patch and with a faster onset of drug
permeation
Drug Permeation through Skin Is Inversely Correlated with Carrier Gel Rigidity
Controlled release plays an essential
role in formulating topical
and transdermal drug delivery systems. In this study, we correlated
the skin permeation of Sesamin, a lipophilic drug, with the rheological
properties of two different organogel carriers, i.e., low molecular
weight gelling agent <i>N</i>-lauroyl-l-glutamic
acid di-<i>n</i>-butylamide (GP-1) and Carbopol polymeric
gels. Although these two gels have distinct network structures, they
share the same trend: the more rigid the gel network and the higher
the gelator concentration, the lower the steady flux of Sesamin through
skin. This negative correlation lies in the fact that organogel network
hinders the diffusion of drug to the gel–skin interface; as
a result, the depletion zone near the interface is non-negligible
and contributes to the resistance of the whole diffusion system, and
thus, the permeation flux is reduced. More interestingly, the dependence
of the steady flux against gel complex modulus at the linear viscoelastic
region followed a “universal” power law regardless of
the gel types, i.e., 1/<i>J</i> = 1/<i>J</i><sub>0</sub> + <i>a</i>(<i>G</i>*)<sup>ε</sup>/<i>C</i><sub>0</sub> with <i>a</i> = 11.25,
ε = 0.21 ± 0.03 for GP-1 gels, and <i>a</i> =
0.16, ε = 1.05 ± 0.06 for Carbopol gels, <i>J</i><sub>0</sub> is the steady flux without gel (<i>G</i>*
= 0), and <i>C</i><sub>0</sub> is the initial concentration
of drug in gels. The empirical formulae are crucial in developing
transdermal organogel systems with controlled release of drug content
through readily obtainable data of their rheological properties. The
explanation for the power law dependence of the steady flux on gel
complex modulus is discussed
Iron Oxide Filled Magnetic Carbon Nanotube–Enzyme Conjugates for Recycling of Amyloglucosidase: Toward Useful Applications in Biofuel Production Process
Biofuels
are fast advancing as a new research area to provide alternative
sources of sustainable and clean energy. Recent advances in nanotechnology
have sought to improve the efficiency of biofuel production, enhancing
energy security. In this study, we have incorporated iron oxide nanoparticles
into single-walled carbon nanotubes (SWCNTs) to produce magnetic single-walled
carbon nanotubes (mSWCNTs). Our objective is to bridge both nanotechnology
and biofuel production by immobilizing the enzyme, Amyloglucosidase
(AMG), onto mSWCNTs using physical adsorption and covalent immobilization,
with the aim of recycling the immobilized enzyme, toward useful applications
in biofuel production processes. We have demonstrated that the enzyme
retains a certain percentage of its catalytic efficiency (up to 40%)
in starch prototype biomass hydrolysis when used repeatedly (up to
ten cycles) after immobilization on mSWCNTs, since the nanotubes can
be easily separated from the reaction mixture using a simple magnet.
The enzyme loading, activity, and structural changes after immobilization
onto mSWCNTs were also studied. In addition, we have demonstrated
that the immobilized enzyme retains its activity when stored at 4
°C for at least one month. These results, combined with the unique
intrinsic properties of the nanotubes, pave the way for greater efficiency
in carbon nanotube–enzyme bioreactors and reduced capital costs
in industrial enzyme systems
Cell patterning and aggregate formation inside microwells.
<p><b>A)</b> Cell patterning. Cells were localized inside the microwells. <b>B)</b> After cell seeding, the cells in the microwell array were cultured in a petri dish and aggregates formed within 24 h. <b>C)</b> Once the aggregate formation is complete inside the microwells, they can be stained. <b>D)</b> Aggregates can be imaged inside microwells. <b>E)</b> Aggregates can be easily released from the microwells by gentle flushing with media for other applications.</p
Aggregate survival tests <i>in vitro</i>.
<p><b>A)</b> Subsets of microwell arrays with 2D monolayer of cell culture (2D) and aggregates of three sizes (S, M, and L). Hydrogen peroxide and anoxia/reoxygenation treatments were employed to induce cell death. EthD (red) and DAPI (blue) staining were performed for the determination of cell death. <b>B)</b> Quantification of dead CSP cells in 2D single layer culture and aggregates with variable diameters subjected to 200 µM-hydrogen peroxide treatment using EthD/DAPI fluorescent intensity ratio. Data were normalized to the vehicle groups of 2D monolayer culture and aggregates in three sizes. <b>C)</b> Quantification of dead CSP cells in 2D single layer culture and aggregates with variable diameters subjected to anoxia/reoxygenation using EthD/DAPI fluorescent intensity ratio. Data were normalized to the vehicle groups of 2D monolayer culture and aggregates in three sizes.</p
CSP cell survival <i>in vivo</i> following cardiac injury.
<p><b>A)</b> Protocol to measure the <i>in vivo</i> survival of CSP aggregates and suspensions. <b>B)</b> Representative serial bioluminescence images (BLI) of mice injected with CSP cell aggregates and CSP single cell suspensions. <b>C)</b> Percentage of CSP cell survival measured with BLI.</p
Aggregate integrity and survival in fluidic manipulations.
<p><b>A)</b> Aggregates formed in microwells can be easily flushed out from the microwell and centrifuged while remaining intact. <b>B)</b> Aggregate can be easily passed through a 30G needle without loosing integrity. <b>C)</b> A representative DAPI/EthD fluorescent image of aggregates before injection. <b>D)</b> A representative DAPI/EthD fluorescent image of aggregates after injection. <b>E)</b> Quantification of dead CSP cells in aggregates passing a 30G needle using EthD/DAPI fluorescent intensity ratio. (All bars represent 100 µm).</p