Biomedical Engineering Reference
In-Depth Information
Fluorescent.immuno-detection.revealed.that.an.attached.FLAG.sequence.remained.intact.
through. the. transfer. process.. Integrity. of. the. FLAG. sequence. demonstrates. retention. of.
amino. acid. sequence. through. the. transfer. event.. LIFT. was. used. at. a. luence. of. 150.mJ/
cm
2
.to.transfer.rabbit.immunoglobulin.G.(IgG)..Fluorescent.microscopy.displayed.a.very.
high. degree. of. retained. activity. as. a. large. majority. of. transferred. IgG. bonded. with. a.
complementary.partner.(Karaiskou.2003;.Zergioti.et.al..2005;.Lin.et.al..2010).
13.4.2.2 Viability of Cells in Laser Direct-Write
Fungi. transferred. with. an. AFA-LIFT. process. survived. at. a. rate. of. 75%. at. a. luence. of.
355.mJ/cm
3
. (Hopp. et. al.. 2004,. 2005)..
Trichoderma longibrachiatum
. survived. transfer. with.
accelerations.on.the.order.of.10
9
.g,.due.to.the.extremely.short.duration.of.the.acceleration,.
(around. 100.ns). as. well. as. the. small. dimensions. of. the. fungi.. Increased. laser. luences.
decrease. viability. in. transferred. yeast. cells. due. to. photolytic. and. thermolytic. effects. as.
well. as. increased. transfer. velocity,. indicating. increased. acceleration.. While. immediate.
cell.death.increased.with.increasing.luence,.the.amount.of.recoverable.cell.damage.did.
not. increase. strongly. with. increasing. luence.. At. the. threshold. energy. for. consistent.
transfer,. viability. upward. of. 75%. was. seen.. Viability. of. cells. is. correlated. with. luence,.
with. luences. of. 258-1482.mJ/cm
2
. causing. a. decrease. in. viability. from. 95%. to. 78%. in.
HT-29.colon.cancer.cells.(Lin.et.al..2010)..This.effect.is.attributed.to.increasing.mechanical.
stresses.in.the.droplet.formation.and.landing.processes..Thermal.and.photolytic.processes.
are. thought. to. be. negligible,. due. to. the. aforementioned. lack. of. increase. in. nonlethal.
cell. damage.. Analysis. of. femtosecond. laser-liquid. interaction. has. revealed. that. energy.
densities.required.for.bubble.formation.are.only.about.1/5.of.the.vaporization.enthalpy..
This.helps.to.explain.the.apparent.lack.of.thermal.side.effects.in.laser.direct-write.transfer.
processes.(Vogel.et.al..2007).
13.4.2.3 Function of Biological Materials in Laser Direct-Write
MAPLE.DW.has.been.used.for.the.transfer.of.hydroxyapatite,.a.mineral.vital.to.the.struc-
ture.of.bone..The.transfer.material.was.deposited.at.submillimeter.resolution.in.discrete.
points,.lines,.and.squares..After.transfer,.a.porous.structure.was.seen,.which.was.able.to.
be. tailored. by. selecting. size. of. the. ceramic. powder,. as. well. as. the. solvent. and. solution.
concentration. before. transfer. (Doraiswamy. et. al.. 2006).. Control. over. surface. roughness.
and.porosity.may.be.an.invaluable.tool.for.the.creation.of.useful.implant/tissue.interfaces.
Protein. printing. is. inherently. different. from. printing. metals. and. other. chemically.
passive. materials.. With. all. biomaterials,. chemical. functionality,. which. is. dependent.
on. multiple. levels. of. structure,. must. be. maintained. through. transfer.. Because. protein.
function.is.dependent.not.only.on.the.order.of.amino.acids.bonded.together,.but.also.the.
more.delicate.folding.structure,.they.are.highly.sensitive.to.temperature.effects;.and.very.
small.changes.can.greatly.alter.their.chemical.behavior..Horseradish.peroxidase,.a.catalyst.
for.the.reduction.of.3,3′-diaminobenzidine,.has.been.transferred.without.loss.of.function.
(Spargo.et.al..2001)..While.peroxidase.is.a.fairly.stable.protein,.this.is.proof.of.concept:.laser.
printing.of.proteins.that.maintains.said.proteins'.functionality.is.possible..It.is.important.to.
note.that.laser.direct-write.printing.processes.do.not.depend.on.the.chemical.structure.of.
the.protein.to.be.transferred..Additionally,.the.type.of.cell.to.be.transferred.is.not.a.critical.
factor.in.predicting.successful.printing..Because.the.transfer.process.is.purely.a.physical.
one,.a.variety.of.proteins.can.be.transferred.with.essentially.the.same.procedure.except.for.
slightly.different.preparation.of.the.print.ribbon.itself..This.ability.to.use.the.same.laser,.
