Biomedical Engineering Reference
In-Depth Information
3.5.1.1.5.4 Combined Drugs (2 in 1)
Priyabrata.et.al.
101
.loaded.two.anticancer.agents.on.the.
same.AuNPs..Vascular.endothelial.growth.factor
(VEGF).is.secreted.by.malignant.cells,.
leading. to. both. neovascularization. and. increased. resistance. to. apoptosis.. AuNPs. were.
successfully. functionalized. with. both. VEGF. antibody-2C3,. as. an. antiangiogenic. agent,.
and.gemcitabine,.as.an.anticancer.agent,.providing.a.2-in-1.system.and.a.model.for.com-
bined.drug.therapy.
3.5.1.1.6 Antibiotics
Saha. et. al.
102
. conjugated. antibiotics. ampicillin,. streptomycin,. and. kanamycin. to. 14. nm.
AuNPs..Conjugation.was.performed.during.the.synthesis.of.the.AuNPs.as.a.result.of.the.
combined.reducing.ability.of.the.antibiotics.and.sodium.borohydride..Targeted.bacterial.
strains.were.
Escherichia coli
DH5a,
Micrococcus luteus
,.and.
Staphylococcus aureus
..Conjugated.
streptomycin. and. kanamycin. proved. more. effective. than. ampicillin,. and. all. antibiot-
ics. were. more. heat. stable. than. their. free. forms.. Ampicillin. activity,. when. conjugated. to.
AuNPs,.was.higher.than.its.free.form.only.at.elevated.temperatures,.and.was.lower.after.
2.weeks.
3.5.1.2 Thermal Therapy
3.5.1.2.1 Cancer
Current.cancer.therapies.are.notorious.for.being.invasive,.toxic,.and.ridden.with.adverse.
effects.that.may.be.localized.or.systemic,.physical.or.psychological..The.effective.elimina-
tion.of.cancer.cells.without.harming.the.surrounding.healthy.tissue.has.been.the.ultimate.
goal.and.challenge.in.cancer.therapy.
Thermal.therapies.have.been.used.to.treat.cancer.in.a.more.localized.manner..They.are.
minimally.invasive.and.can.be.used.in.patients.who.are.not.suitable.candidates.for.surgery.
or.have.inoperable.tumors.
95
.Thermal.therapies.used.include.cryotherapy,
103
.microwaves,
104
.
focused.ultrasound,
105
.radiofrequency.(RF).ablation,
106
.and.laser.photothermal.therapy.
107
.
Subjecting.cells.to.temperatures.between.41.and.47°C.induces.apoptosis,
108
.an.organized.
manner. of. cell. death,. which. involves. normally. functioning. proteins.. At. temperatures.
above.50°C,.necrosis.occurs,.which.is.a.form.of.cell.death.based.on.protein.denaturation.
accompanied.by.lipid.melting.
109
.However,.when.using.these.nonspeciic.techniques,.it.is.
dificult.to.accurately.target.only.the.cancer.cells.without.also.destroying.the.surrounding.
normal.tissue.
3.5.1.2.1.1 Photothermal Therapy (PTT)
Photothermal.therapy.(PTT).using.AuNPs.is.simi-
lar.to.combining.PDT.and.thermal.therapy.techniques,.but.with.higher.speciicity,.uptake,.
and.penetration..It.is.also.less.cytotoxic,.with.little.or.no.injury.to.normal.tissue.
74
.Tissues.
have. an. “optical. transparency. window”. that. corresponds. to. the. NIR,. between. 750. and.
1,100. nm,
81
. allowing. deeper. penetration. of. light,. while. minimizing. absorption. by. water.
and.hemoglobin.
19,75
.Owing.to.their.optical.and.physical.properties,.AuNPs.can.be.tuned.
so. that. their. SPR. falls. in. the. NIR. region,. while. at. the. same. time. requiring. lower. laser.
energy.
75,95,110
AuNPs. are. injected. either. systemically. (intravenous. route). or. directly. into. the. tumor..
Once. the. AuNPs. have. reached. the. target. site,. whether. by. passive. or. active. means,. short.
laser. pulses. are. directed. at. the. site. and,. via. the. AuNPs'. electron-electron. collisions. fol-
lowed.by.electron-phonon.interactions,.this.light.energy.is.converted.into.heat,.leading.to.
thermal.ablation.of.the.malignant.cells,.which.are.more.sensitive.to.heat.than.normal.cells.
