Biomedical Engineering Reference
In-Depth Information
proliferation.and.differentiation.in.tissue.engineering..Laser.direct-write.allows.for.pat-
terning. of. the. receiving. substrate,. permitting. modiication. of. the. cell. environment.. As.
well,.cells.can.be.grown.and.deposited.inside.microbeads,.as.described.earlier..Altering.
the.material.composition.of.the.microbead.will.allow.for.further.control.of.the.mechani-
cal.environment.experienced.by.cells.
An. additional. advantage. of. the. laser. direct-write. process. when. compared. with. other.
luid. jet. printing. strategies. is. the. capacity. of. the. machine. to. be. used,. with. little. to. no.
modiication,.for.laser-based.ablative.micromachining.as.well.as.pulsed-laser.deposition.
(PLD). and. MAPLE. processing. (Jelinek. et. al.. 2007).. The. same. mechanism. used. for. LIFT,.
AFA-LIFT,. and. MAPLE. DW. procedures. allows. for. microetching. and. other. material.
removal.forming.processes..These.processes.can.also.be.conducted.for.materials.that.are.
normally.laser.transparent,.such.as.fused.silica,.by.ablation.of.adjacent.highly.absorbing.
liquids,. in. analogy. to. the. AFA-LIFT. process. (Kawaguchi. et. al.. 2003).. These. techniques.
will. allow. for. direct. modiication. of. tissue. scaffolds. with. the. same. laser. setup. used. for.
laser.direct-write..One.more.interesting.use.for.laser.processing.of.biological.materials.is.
in.DNA.modiication..Sub-20.fs.pulses.at.low.energies.less.than.20.mW.have.been.shown.
to. safely. open. transient. nanopores. in. cell. membranes,. usable. for. transfection. (Lee. and.
Doukas.1999)..The.same.strategy.can.be.used.for.drug.delivery..These.systems.work.well,.
when. compared. to. chemical. techniques. that. have. been. developed. far. more. extensively..
The. mechanism. behind. the. perfusion. of. DNA. is. via. a. laser-induced. stress. wave.. This.
stress.wave.has.been.shown.to.render.plasma.membranes.permeable.without.harming.cell.
viability.(McAuliffe.et.al..1997;.Mulholland.et.al..1999)..Exogenous.drugs.can.be.taken.up.
by.the.cell.at.this.time,.and.trapped.inside.when.the.membrane.quickly.returns.to.normal..
This.novel.technique.demonstrates.that.there.are.many.possible.uses.for.laser.processing.
in.biomaterials,.and.that.a.single.system.can.be.used.for.extensive.forming,.machining,.
printing,. and. other. unique. modes. of. processing,. which. may. all. be. vital. for. the. precise.
manufacturing.techniques.seen.to.be.critical.in.the.engineering.of.functional.tissues.
Laser.direct-write.is.enabling.progress.toward.the.fabrication.of.thick.tissues..Current.
tissue. fabrication. uses. the. seeding. of. cells. onto. a. matrix. or. scaffold.. Unfortunately,.
homogeneous. seeding. must. inherently. disallow. the. creation. of. organs. and. tissues.
with.complex,.heterogeneous.structures..Fine.placement.of.cells.onto.the.matrix.will.be.
critical.for.the.assembly.of.functional.tissue;.as.seen.earlier,.laser.direct-write.technology.
presents.itself.as.a.method.of.accurate.placement.of.cells.and.biomolecules.in.both.2D.and.
3D. arrangements.. As. well,. laser. direct-write. enables. deposition. and. removal. of. a. wide.
variety.of.materials,.both.organic.and.inorganic,.allowing.for.a.one-machine.development.
of. complex. arrangements. of. diverse. materials. potentially. unachievable. by. other. means..
Novel.structures.will.elucidate.questions.in.biology.and.open.the.door.to.the.engineering.
of.functional.tissues.and.organs.
Glossary
AFA-LIFT
:.absorbing.ilm-assisted.laser-induced.forward.transfer
BDO
:.beam.delivery.optics
BioLP
:.biolaser.printing
CAD/CAM
:.computer-aided.design/computer-aided.manufacturing
FEM
:.inite.element.modeling
