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Vincenzo F. Curto

Ionic Liquids in biosensors: influence of

hydrated choline based ILs on the

bio-functionality of Lactate Oxidase

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Electrochemical and wearable biosensors

Long-life bioreceptor issues

"  narrow pH range activity

"  temperature range stability

"  limitations that are associated with the use of conventional aqueous electrolytes

!

Wearable sensors allow the continuous monitoring of a person’s physiology in a natural setting

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Ionogel & OECTs: Lactate Sensor

3

V. F. Curto, et al., J. Mater. Chem., 22, 4440 (2012).

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Enzyme: Lactate Oxidase (LOx) from Aerococcus Viridans

–  !-hydroxy-acid oxidase flavoenzyme family

–  Molecular Weight: 80 kDa

Choline based ILs

1. Choline aminoacetate

2. Choline dhp

3. Choline levulinate 4. Choline bis(2-ethylhexyl)phosphate (BEH)

5. Choline formate

6. Choline tartrate

7. Choline gallate

8. Choline dibutylphosphate

9. Choline valporate

10. Choline nitrate

11.  Choline chloride

4

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234444*

25444*

26444*

27444*

28444*

4*

8444*

7444*

6444*

5444*

34444*

38444*

37444*

36444*

35444*

394* 844* 834* 884* 8:4* 874* 8;4*

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"%"++(,

-.(/0

%1)"2%.!

3 %)!4+

567%

%

8#9"+"$2/:%1$!7%

8;<+*=>?@A>*B>CDEF*

9;<+*

8;<+*CG>A*B>CDEF*

2;444*

27444*

2:444*

28444*

23444*

4*

3444*

8444*

:444*

7444*

;444*

6444*

H444*

394* 844* 834* 884* 8:4* 874* 8;4*

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"%"++(,

-.(/0

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3 %)!4+

567%

%

8#9"+"$2/:%1$!7%

8;*<+*=>?@A>*B>CDEF*

9;<+*

8;<+*CG>A*B>CDEF*

Enzyme structure - Cirlcular Dichroism

PBS Choline dhp

5

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0

20

40

60

0 1.5 3 4.5 6

Velo

city

[U m

g-1 ]

Concentration [mM]

IL free Choline Cl choline dhp choline formate Choline nitrate Choline levulinate

Enzyme Kinetic

6

Km [mM] ;<%=&""% 0.366

>:4+($"%>+% 0.377 >:4+($"%):,% 0.825

Km [mM] >:4+($"%=4&!#/"% 0.926 >:4+($"%$(/&#/"% 0.487

>:4+($"%+"9*+($#/"% 0.674

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0

25

50

75

100

0 30 60 90 120 150

Nor

mal

ised

enz

yme

velo

city

(v/v

o) %

time/day

#-*?A>>*

+B@IJE>*+I*

+B@IJE>*KBL*

+B@IJE>*"JMACM>*

+B@IJE>*?@ANCM>*

+B@IJE>*MCAMACM>*

+B@IJE>*I>OPIJECM>*

+B@IJE>*KJ=PMQILB@RLBCM>*

Long Term stability – T= 5 °C

7

!"#$%&'#()*+,--%.%*/!0-#"***!***/!0-#"*+#()*!"#$%&'#()***!***()"/1--*"1(#,"1-*#"'(#(!(%**

Dr. Dion Khodagholy Prof. Róisín Owens Prof. George Malliaras

Dr. Fernando Benito-Lopez Prof. Dermot Diamond

Dr. Vijay Ranganathan Prof. Doug MacFarlane

Acknowledgements

07/CE/I1147

Research Career Start Programme 2010