Drug Delivery wi ith Temperature Sensitive L Liposomes Gino - - PowerPoint PPT Presentation

Drug Delivery wi Sensitive L

 Gino Graziano  Chemistry Major  Santa Barbara City College  Santa Barbara City College  Faculty Advisor: Dr. Joseph Zasad  Department of Chemical Enginee

Mentor: Tallie Forbes

 Mentor: Tallie Forbes  Funding from National Institutes

ith Temperature Liposomes

dzinski ering

• f Health (NIH)

Liposomes and Mecha Liposomes and Mecha

 Phospholipid bilayer (cell mem

Mechanism:

Drug permeates membrane and is encapsulated

anism anism

Water-compatible head mbrane material) Water compatible head Water-incompatible tail

Distinguishing Characteristic Distinguishing Characteristic

 Naturally aggregates in “leaky”

cancer tissue Temperature Sensitive

 Temperature Sensitive

(releases contents at ~40°C)

Big Picture g

 More effective cancer trea

sensitive liposomes as vehicl p

Current Chemotherapy

 Dispersed  Dispersed  Limited dosages  Wide range of adverse effects

atments by using temperature les for chemotherapy drugs py g

Tumor Tumor

Liposome Delivery

 Targeted  Targeted  Larger effective dosage  Reduced adverse effects

Controlled release

 Controlled release

Research Goals

 What loading conditions giv

encapsulation efficiency?

amount of drug encapsulated total drug added to sample = g p

ve the highest

encapsulation efficiency =

Variables

pH gradient (ΔpH)

 pH gradient (ΔpH)  Temperature  Time  Concentrations

 Using gold nanoshells for co  Using gold nanoshells for co

M

1) 2) 2) 3) 4) Go Polymer tethers

• ntrolled release
• ntrolled release

M h i Mechanism

) Tethering of nanoshells to liposome ) Irradiation with near infrared laser ) Irradiation with near-infrared laser ) Liposome is heated to release temperature ) Drug is released

• ld nanoshell

Method: Fluorescence Method: Fluorescence

 Measuring concentration of d

through fluorescence intensity through fluorescence intensity

Generally, intensity is directly related to concentration:

I = kC

related to concentration:

Proportionality constant constant

 Fluorescence is measured

b f d ft t i

Chal

 Phot

S lf before and after rupturing loaded liposomes

 Self  Che

e Spectroscopy e Spectroscopy

rug y llenges

todecomposition hi g

• quenching

mical interaction

Preliminary Results: E Preliminary Results: E

 Change in fluorescence intens

how much drug was encapsulat

30.0

Increased pH Gradient

how much drug was encapsulat

10.0 20.0 ∆ I 3.4 4.4 0.0 ∆pH

I d D A t

20.0

Increased Drug Amount

0.0 10.0 ∆ I 2.5 μL 7.5 μL Amount of drug added

Encapsulation Encapsulation

sity (ΔI) is indicative of ted

30.0

Increased Loading Time

ted

10.0 20.0 ∆ I 2 hrs 16.5 hrs 0.0 Loading time

I d L di T t

60.0 80.0

Increased Loading Temperature

0.0 20.0 40.0 Δ I 20°C 35°C Loading temperature

120.0

Method Comparison

60.0 90.0 Δ I 0 0 30.0 0.0 Same conditions

Summary

Increases in encapsulation seen h when:

 pH gradient is increased  Loading time is increased

L di t t i i d

 Loading temperature is increased  Drug to lipid ratio is increased

Two loading schemes used

Double buffer method

 Manually established pH

gradient gradient

Ion gradient method

 Passively established pH

gradient

Ion gradient loading shows to be much more efficient to be much more efficient

Preliminary Results: R Preliminary Results: R

Without Nanoshells

 Loaded liposomes irradiated 20000 30000

Without Nanoshells

Intensity 10000 20000

Bulk Temperature Release Temperat

Release

With Nanoshells

Release

with near-infrared laser

8000 12000

With Nanoshells

Intensity 4000 8000

78 71% Release

: 37±1°C ure: 40°C 78.71% Release

Conclusions Conclusions

 Increasing encapsulation tren

g p loading time, temperature, p

 Ion gradient loading much m  Significant release observed

g relatively effective nanoshell nd with increasing H gradient and drug/lipid ratio

• re effective

with nanoshells, suggests , gg tethering

Future Work: Future Work:

L k t

 Leakage measurement  Comparative release with d  More encapsulation data sp  More encapsulation data, sp

time and concentration different tethering methods pecifically regarding pecifically regarding

Acknowledgments Acknowledgments

Tallie

• Dr. Joseph

The Zasa

• Dr. Jens

Dr Nich

• Dr. Nich
• Dr. Ar

e Forbes h Zasadzinski adzinski Lab s-Uwe Kuhn holas Arnold holas Arnold rica Lubin

Ion Gradient Method Ion Gradient Method

(NH4)2SO4 NH3 + U Further equilibria: SO NH4HSO4 NH H2SO4 H+ + HSO4

• H+ +

+ NH4HSO4 ncharged (leaves the liposome) SO H3 + H2SO4 + HSO4

• + SO4

2-

Acidification of interior