3.3 Physical
Methods
3.3.1 Microprojection
Array to Deliver OVA [37]
1. Microprojection arrays are produced using a controlled
manufacturing process. The finished microprojection array is
a titanium screen with a defined microprojection pattern, density, and length. Microprojection arrays used are generally 1 or
2 cm
2 in area.
2. Microprojection arrays are coated by immersion in a 1%, 5%, or
20% sterile aqueous solution of OVA (w/v, Grade V, Sigma
Chemical Co., St. Louis, MO). Excess solution is removed by
forced air and the arrays are air-dried for 1 h at ambient
conditions.
3. The number of OVA coated on the microprojection arrays is
determined using FITC–OVA against known standards by
luminescence spectrometry (excitation 494 nm, emission
520 nm).
4. Microprojection arrays coated with FITC–OVA are also
inspected visually by fluorescence microscopy before and after
skin application.
5. After coating and drying, the microprojection array is affixed to
an adhesive patch comprised of a low-density polyethylene
backing with a polyisobutylene adhesive. The final systems
should have a total patch area of 8 cm
2 containing either a
1 or 2 cm
2 area microprojection array.
6. Animals are anesthetized using a gas delivery system (isoflurane
3–3.5%, O 2 2–2.5 L/min) and skin treatment sites (lateral area
of the thorax) are cleaned with isopropyl alcohol wipes (70%)
and allowed to dry.
7. The skin sites should be lightly stretched manually during the
system application with an impact applicator. After application,
the system is left on the skin for specified times for efficient
delivery.
3.3.2 Microporation
1. A prototype microporation system (Altea) [38] is used to create
an array of microscopic pores in the stratum corneum of the
mouse abdomen.
2. Each tiny spot of stratum corneum is removed by the application of focused thermal energy. Electrically heated wires of
small diameter are used for skin removal.
3. The microporation tip comprises of a set of 80 μm diameter
tungsten wires strapped over the edge of a ceramic substrate
and electrically connected to the control circuitry via copper
traces on each side of the substrate.
4. The temperature of the tip to be in contact with the skin is
calibrated with the use of an optical calibrator device. The
microporation parameters remain the same for various mice
models tested.
Methods of Needle-Free Injections
443
Methods
3.3.1 Microprojection
Array to Deliver OVA [37]
1. Microprojection arrays are produced using a controlled
manufacturing process. The finished microprojection array is
a titanium screen with a defined microprojection pattern, density, and length. Microprojection arrays used are generally 1 or
2 cm
2 in area.
2. Microprojection arrays are coated by immersion in a 1%, 5%, or
20% sterile aqueous solution of OVA (w/v, Grade V, Sigma
Chemical Co., St. Louis, MO). Excess solution is removed by
forced air and the arrays are air-dried for 1 h at ambient
conditions.
3. The number of OVA coated on the microprojection arrays is
determined using FITC–OVA against known standards by
luminescence spectrometry (excitation 494 nm, emission
520 nm).
4. Microprojection arrays coated with FITC–OVA are also
inspected visually by fluorescence microscopy before and after
skin application.
5. After coating and drying, the microprojection array is affixed to
an adhesive patch comprised of a low-density polyethylene
backing with a polyisobutylene adhesive. The final systems
should have a total patch area of 8 cm
2 containing either a
1 or 2 cm
2 area microprojection array.
6. Animals are anesthetized using a gas delivery system (isoflurane
3–3.5%, O 2 2–2.5 L/min) and skin treatment sites (lateral area
of the thorax) are cleaned with isopropyl alcohol wipes (70%)
and allowed to dry.
7. The skin sites should be lightly stretched manually during the
system application with an impact applicator. After application,
the system is left on the skin for specified times for efficient
delivery.
3.3.2 Microporation
1. A prototype microporation system (Altea) [38] is used to create
an array of microscopic pores in the stratum corneum of the
mouse abdomen.
2. Each tiny spot of stratum corneum is removed by the application of focused thermal energy. Electrically heated wires of
small diameter are used for skin removal.
3. The microporation tip comprises of a set of 80 μm diameter
tungsten wires strapped over the edge of a ceramic substrate
and electrically connected to the control circuitry via copper
traces on each side of the substrate.
4. The temperature of the tip to be in contact with the skin is
calibrated with the use of an optical calibrator device. The
microporation parameters remain the same for various mice
models tested.
Methods of Needle-Free Injections
443