effect of synthesis conditions on properties citric acid_2

8/12/2019 Effect of Synthesis Conditions on Properties Citric Acid_2

1/11

Microelectronic Engineering 110 (2013) 329334

Contentslists

available at SciVerse ScienceDirect

Microelectronic Engineering

j o u r n a l o ! e " a g e # $ $ $ % e l s ev i e r % c o ! & l o c a t e & ! e e

E''ect o' sntesis conitions on te "ro"erties o' citric*aci coate iron

o+ie nano"articles

,% ,ia- .%/% Ma

a- C%% ,eung

b- .%/% Can

c- %.% Can

c- % ong

- %%% ong

a-

aDe"art!ent o' Electrical an Electronic Engineering- e 5niversit o' 6ong .ong- 6ong .ong

bDe"art!ent o' 7""lie sics- 6ong .ong oltecnic 5niversit- 6ong .ong

cDe"art!ent o' Ce!istr- e 5niversit o' 6ong .ong- 6ong .ong

De"art!ent o' sics- 8anjing 5niversit- Cina

a r t i c l e i n ' o

7rticle istor#

7vailable online 2 :ebruar2013

.e$ors#

Magnetic nano"article

Citric aci

Si;e

e!"erature

a b s t r a c t

Citric aci is a $iel acce"te coating !aterial in nano"article 'abrication 'or bio!eical

a""lications $ile iron o+ie is one "o"ular !agnetic !aterial $it e+cellent "ro"erties 'or use in

nano"article 'or!% 6o$ever- te e''ect o' sntesis conitions on te "ro"erties o' iron o+ie

nano"articles is not su''i*cientl unerstoo% 6ere- citric*aci coate iron o+ie nano"articles $ere

sntesi;e base on te co*"reci"itation !eto troug bot one*ste" an t$o*ste" "rocess-

res"ectivel% e citric aci $as ae at i''erent stages- an various coating te!"eratures $ere

use in te t$o*ste" "rocess% e nano*"articles $ere caracteri;e b !ulti"le tecni n! iron o+ie nano"articles%

2013 Elsevier ?%V% 7ll rigtsreserve%

1% =ntrouction

Magnetic nano"articles ave attracte broa attention ue

to teir "otential bio!eical a""lications- suc as contrast

agents 'or !agnetic resonance i!aging (M@=)- A1B eating

!eiators 'or cancer tera" ("erter!ia)- A2B an

!agnetic labels 'or bio*sensing A3B% e s"eci'ic nano"article

"ro"erties !ust be tailore to eac a""lication to obtain te

esire results% Magnetic nano*"articles are generall

re
http://dx.doi.org/10.1016/j.mee.2013.02.045http://www.sciencedirect.com/science/journal/01679317http://www.sciencedirect.com/science/journal/01679317http://www.elsevier.com/locate/meehttp://var/www/apps/conversion/tmp/scratch_5/HYPERLINK%23page5http://var/www/apps/conversion/tmp/scratch_5/HYPERLINK%23page5http://var/www/apps/conversion/tmp/scratch_5/HYPERLINK%23page5http://var/www/apps/conversion/tmp/scratch_5/HYPERLINK%23page5http://var/www/apps/conversion/tmp/scratch_5/HYPERLINK%23page5http://var/www/apps/conversion/tmp/scratch_5/HYPERLINK%23page5http://var/www/apps/conversion/tmp/scratch_5/HYPERLINK%23page5http://var/www/apps/conversion/tmp/scratch_5/HYPERLINK%23page5http://var/www/apps/conversion/tmp/scratch_5/HYPERLINK%23page5http://var/www/apps/conversion/tmp/scratch_5/HYPERLINK%23page5http://var/www/apps/conversion/tmp/scratch_5/HYPERLINK%23page5http://var/www/apps/conversion/tmp/scratch_5/HYPERLINK%23page5http://var/www/apps/conversion/tmp/scratch_5/HYPERLINK%23page5http://var/www/apps/conversion/tmp/scratch_5/HYPERLINK%23page5http://var/www/apps/conversion/tmp/scratch_5/HYPERLINK%23page6http://var/www/apps/conversion/tmp/scratch_5/HYPERLINK%23page6http://var/www/apps/conversion/tmp/scratch_5/HYPERLINK%23page6http://var/www/apps/conversion/tmp/scratch_5/HYPERLINK%23page6http://var/www/apps/conversion/tmp/scratch_5/HYPERLINK%23page6http://var/www/apps/conversion/tmp/scratch_5/HYPERLINK%23page6http://var/www/apps/conversion/tmp/scratch_5/HYPERLINK%23page6mailto:[email protected]:[email protected]:[email protected]://dx.doi.org/10.1016/j.mee.2013.02.045http://dx.doi.org/10.1016/j.mee.2013.02.045http://www.sciencedirect.com/science/journal/01679317http://www.elsevier.com/locate/meehttp://var/www/apps/conversion/tmp/scratch_5/HYPERLINK%23page5http://var/www/apps/conversion/tmp/scratch_5/HYPERLINK%23page5http://var/www/apps/conversion/tmp/scratch_5/HYPERLINK%23page5http://var/www/apps/conversion/tmp/scratch_5/HYPERLINK%23page5http://var/www/apps/conversion/tmp/scratch_5/HYPERLINK%23page6http://var/www/apps/conversion/tmp/scratch_5/HYPERLINK%23page6mailto:[email protected]://dx.doi.org/10.1016/j.mee.2013.02.045http://dx.doi.org/10.1016/j.mee.2013.02.045


2/11

to 'in a goo !eto to 'unctionali;e te sur'ace o'

nano"articles $it te a""ro"riate ce!icals A10B% o i!"art

aitional 'unc*tionalit an&or conjugate $it biologicall

active agents- iron o+ie nano"articles usuall bear 'unctional

grou"s on teir sur*'aces- suc as "os"ates- sul"ates-

an carbo+lates% ' tese 'unctional grou"s- carbo+late is

te strongest biner A11B% n te oter an- so!e bining

a''init !a be lost troug steric inrances b large

sur'actant !olecules or long "ol!er cains- $ic coul be

easil overco!e $it te use o' s!all !olecules A12B%

7!ong various s!all !olecules- citric aci (C6F)- a bio*

co!"atible sort*caine tri*carbo+lic aci- as been

e+tensivel use 'or te "re"aration o' a


3/11

330 ,% ,i et al% & Microelectronic Engineering 110 (2013) 329334

is ae uring te "article nucleation an

gro$t A21-22B- or via a t$o*ste" "rocess

$ere te sur'actant coating is a""lie

ine"en*entl a'ter nano"article sntesis

A23B% Since te citrate ions are no$n to

inter'ere $it te 'or!ation an gro$t o' iron

o+ie nano"articles- A21B an "rocess

te!"erature as been 'oun to i!*"act tenanocrstal sur'ace ligan na!ics- A24B it is

$ort$ile to investigate te in'luences o' te

sntesis conitions on te nano"articles%

is is a critical an 'una!ental $or to

caracter*i;e te sntesis o' !agnetic

nano"articles in orer to o"ti!i;e teir

resulting "ro"erties%

6ere- $e ave sntesi;e citric*aci

coate iron o+ie nano*"articles using te co*

"reci"itation !eto troug bot a one*ste"

an t$o*ste" coating "rocess% e e''ects

introuce b i''er*ent sntesis conitions-

aing te citric aci at i''erent stages an

using various coating te!"eratures in t$o*ste" "rocess- are ten co!"are% e i!"act

o' te citric*aci coating on te !ag*netic

beavior is also investigate on uncoate iron

o+ie cores $it i''erent si;es%

2% E+"eri!ents

2%1% Materials

:erric clorie e+arate (:eCl3 62-

P99J)- 'errous sul*'ate e"tarate (:eS4

62- P99%0J)- soiu! ro+ie (P9FJ)-

an citric aci (P9FJ) $ere "urcase 'ro!Sig!a7l*ric (5S7)% 7ll ce!icals $ereuse as receive% e uncoate iron o+ienano"articles $it si;e close to 9 n! (59)$ere su"*"lie b ,i


4/11

si;e- as su!!ari;e in able 1% Sa!"les C1

an C2 $ere obtaine b using te 1st

!eto an 2n !eto- res"ectivel%

Sa!"les C3*50*90- C3*50*0- C3*50*>0- an

C3*50*30 $ere obtaine b using te 3r

!eto uner i''erent coating te!"eratures%

Sa!*"les C3*59*90 an C3*52>*90 $ere

obtaine b coating te co!*!erciall

"urcase uncoate nano"articles $it citric

aci using te "ost*sntesis coating "rocess(3r !eto) at 90 ,C $it si;es o' 9 n! (59)

an 2> n! (52>)- res"ectivel%

2%3% 8ano"article caracteri;ation

e "resence o' caracteristic 'unctional

grou"s coate on te nano"article sur'aces

$as eter!ine using :ourier trans'or!

in'rare s"ectrosco" (:*=@)% e :*=@

s"ectra o' te sa!"les $ere obtaine $it a

Si!a;u :=@*F300 s"ectro!eter using .?r

"ellets% e si;e an !or"olog o' te

sa!"les $ere observe b trans!ission

electron !icrosco" (EM- ili"s CM100)%e rona!ic si;e o' te nano"articles in

$ater $ere !easure b na!ic ligt

scattering (D,S) using a Malvern etasi;er

3000 (Malvern- 5.)% e !agnetic "ro"ert o'

te lo"ili;e sa!"le "o$ers $as

!easure at roo! te!"erature b using a

vibrating sa!"le !agneto!eter (VSM-

,aesore VSM 400)% e !agneti*;ation

$as !easure over a range o' a""lie 'iel

'ro! 10-000 e to 10-000 e% e iron o+ie

co!"osition $as eter*!ine b using

ter!al gravi!etric analsis (K7- erin*

El!er K7*)% e !ass loss o' >10 !g o'

lo"ili;e sa!"le $as !on*itore uner 82at te!"eratures 'ro! >0 ,C to 00 ,C at a

rate o' >0 ,C&!in%

3% @esults an iscussion

Success'ul citric*aci enca"sulation o' teiron o+ie nano"arti*cles- sntesi;e usingte !etos as escribe in te e+"eri!en*tal

section- $as con'ir!e b te :*=@ results%:ig 1 so$s te re"resentative :*=@s"ectru!s o' te citric aci coate "articles(C1- C2- C3*50*90- C3*59*90- an C3*52>*

90)% e "eas at aroun >0 c!1 inicate

te "resence o' an iron o+ie seleton in all

te sa!"les% e "eas near 130 c!1an

141> c!1- re"resenting carbo+late (C )

stretcing- $ere 'oun in all te citric aci

coate sa!"les in our e+"eri!ents% e"resence o' tese "eas is evience o' te'or!ation o' te citric aci coating aroun teiron o+ie cores A12-2>-2B%

3%1% =n'luence o' aing citric aci at i''erentstages

@e"resentative EM i!ages o' te citric*

aci coate iron o+ie nano"articles

sntesi;e uner si!ilar te!"eratures using

eac o' tree enca"sulation tecni


5/11

,% ,i et al% & Microelectronic Engineering 110 (2013) 329334 331

able 1

:abrication conitions o' citric coate an uncoate iron o+ie nano"articles% a

8o!enclature @eaction t"eSntesis

te!" Coating te!"

50 5ncoate F0 8&7

C1 1st !eto ("re*aition !eto)F0-90

C2 2n !eto ("ost*aition !eto) F0 90

C3*50*90 3r !eto (2*ste" !eto) F0 90

C3*50*0 3r !eto (2*ste" !eto) F0 0

C3*50*>0 3r !eto (2*ste" !eto) F0 >0

C3*50*30 3r !eto (2*ste" !eto) F0 30

C3*52>*90 3r !eto ("ost coating) 8&7 90

C3*59*90 3r !eto ("ost coating) 8&7 90

aSa!"les C1 an C2 $ere obtaine b using te 1st !eto an 2n !eto- res"ectivel%

Sa!"les C3*50*90- C3*50*0- C3*50*>0- an C3*50*30 $ere obtaine b using te 3r!eto uner i''erent coating te!"eratures (90 ,C- 0 ,C- >0 ,C- an 30 ,C)% Sa!"les C3*59*90 an C3*52>*90 $ere obtaine b coating te uncoate nano"articles o' i''erent si;es(average ia!eters o' 9 n! an 2> n!) $it citric aci using te "ost coating "rocess o' 3r!eto uner te coating te!"erature o' 90 ,C%

:ig% 1% :*=@ s"ectra o' citric aci coate (C1- C2- C3*

50*90- C3*59*90- an C3*52>*90) an uncoate (50)

iron o+ie nano"articles%

ultra*s!all si;e o'

C1 soul be

ue to te

"resence o' citricaci uring te

nucleation ste"-

since te citric

aci $as "re*ae into te 'errous an 'erric

solutions be'ore te co*"reci"itation reaction

starte% e asor"tion o' citrate ions on te

nuclei sur'aces can e''ectivel inibit te

gro$t o' te nuclei- A21B $ic causes te

'inal "rouct C1 $it !uc s!aller si;es (

n!) tan sa!"les C2 an C3*50*90%

7itionall- te iron o+ie nano"articles in

sa!"le C2 is"lae a less s"erical

!or"olog tan te oter tree sa!*"les%

Since te sa"e o' te iron o+ie

nano"articles can be a''ecte b te "6 valueuring sa!"le "re"aration- A1B te less

s"erical !or"olog o' sa!"le C2 !igt be

ue to te "6 cange cause b te aitiono' citric aci uring "article gro$t% e

!ecanis! o' tis "eno!enon nees 'urter

stu%

3%2% =n'luence o' coating te!"erature in t$o*ste" "rocess

e e''ect o' i''erent coating te!"erature

in te t$o*ste" "ro*cess (3r !eto) on te

asor"tion o' citric aci aroun "article

sur'ace an te "article rona!ic si;e

$ere stuie using K7 an D,S-

res"ectivel% e citric*aci coate sa!"les

C3*50*90- C3*50*0- C3*50*>0- an C3*50*

30 $ere sntesi;e using te 3r !eto

using i''erent "ost*sntesis coating

te!"era*tures o' 90 ,C- 0 ,C- >0 ,C an 30

,C- res"ectivel% e $eigt "er*centage o'

te iron o+ie cores in te sa!"les C3*50*90-

C3*50*0- C3*50*>0- an C3*50*30 $ere

a""ro+i!atel 94%FJ- 9>%3J- 9%2J an

9%>J- res"ectivel (:ig% 3)% e ecrease o'

te citric aci coat*
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6/11

ing content coul be observe 'ro! >%2J to

3%>J as te "ost*sn*tesis coating

te!"erature ecrease 'ro! 90 ,C to 30 ,C%

e 'or!ation o' a citric aci coating laer on

te "article sur'ace is no$n to be te

ce!ical bon 'or!ation bet$een te

carbo+l grou"s o' citric aci on te :e*6

sites o' te iron o+ie nano"ar*ticles A2FB%Since te ce!ical reaction rate increases

$it te!"er*ature- te asor"tion o' citric aci

onto te "article sur'ace coul be enance

b te increase coating te!"erature% us-

te in*crease coating te!"erature coul

enance te citric*aci coating rate- an ere

it $as 'oun tat te sa!"le C3*50*90 $it

coating te!"erature o' 90 ,C containe te

igest sur'ace coverage o' cit*ric aci on te

nano"articles%

e average rona!ic si;es $eigte

b intensit an "olis"ersit values o' tese

sa!"les are re"orte in able 2%

e rona!ic si;e o' C3*50*90 (>2%9 n!)-

(9%1n!)-

C3*50*>0

(91%1 n!)-an

C3*50*30

creaseas te coating te!"erature

ecrease

30 ,C% Since te iron o+ie core si;es in tese

sa!"les $ere te sa!e as te uncoate

nano"articles 50 (13 n!- :ig% 2)- teir in*

crease rona!ic si;e $it ecrease

"ost*sntesis coating te!"erature coul be

e+"laine b a reuction in te citric aci

coating on te iron o+ie cores as te

te!"erature ecrease- $ic $as con'ir!e

b te K7 results (:ig% 3)% e nano"article

clusters coul be 'or!e $en tere $ere not

enoug sur'actants to ee" te! se"arate-

an te clustering coul increase te

rona!ic si;e o' nano"articles A29B% e

nano"articles (50) $it no coating aggregate

into large clusters in D= $ater $i t

rona!ic si;es o' tens o' !icro*!eters%

e si;e istribution o' te sa!"les is

e+"resse in te "olis"ersit ine+ (%=%)-$ic corres"ons to te variance o' te si;e

istribution o' te nano"ar*ticles% e %=%

value o' te sa!"les $it citric aci coating at

i''er*ent te!"erature- C3*50*90- C3*50*0-

C3*50*>0- an C3*50*30- $ere 0%22- 0%1-

0%2>- an 0%2- res"ectivel% 6o$ever- it

soul be note tat te si;e istribution o'

tese sa!"les oes not ave a si!"le

correlation $it te citric aci sur'actant

coverage aroun nano"articles alone% e

C3*50*90 containe te igest content o'

citric aci sur'actant coating in tese 'our

sa!"les as inicate b K7 result ( :ig% 3)

but so$e less o!ogeneous nano"article

si;e istribution (0%22) tan te one o' C3*50*0 (0%1) $ile te C3*50*0 is"lae te

s!allest %=% value a!ong tese 'our sa!*"les

in our stu% :or te sa!"le rona!ic

si;e istributions- "art o' te is"ersit $as

resulte 'ro! "olis"ersit in te single citric*

aci coate iron o+ie nano"articles $ile

so!e is"ersit !a be cause b variations

in te nanocluster si;es% n one an- te

si;e istribution o' te iniviual nano"articles

beca!e nar*ro$er as te sur'actant*to*$ater

ratio ecrease A24B% us as te content o'

citric aci ecrease in te 'inal "roucts- te

si;e istribution o' te single citric aci*coate

iron o+ie $oul be
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7/11


:ig% 2% EM i!ages o' sntesi;e citric aci coate iron o+ie nano"articles troug tree !etos an uncoate iron o+ie nano"articles (a) C1- (b) C2- (c) C3*50*90- an

() 50%

able 2

6rona!ic si;e o' iron o+ie nano"articles coate $it citric aci at i''erentte!"eratures- in D= $ater%

Sa!"les Mean ia!etera (n!) an "olis"ersit ine+

b

C3*50*90>2%9

A0%22B

C3*50*09%1

A0%1B

C3*50*>091%1

A0%2>B

C3*50*30132%9

A0%2B

a Mean "article si;e result 'ro! tree !easure!ents- $eigte b intensit%

bolis"ersit ine+ values (%=%)- given in bracets- range 'ro! 0 to 1G a iger

value inicates a less o!ogeneous nano"article si;e istribution%

:ig% 3% K7 results o' iron o+ie nano"articles coate $it citric aci at i''erent

te!"erature in te 3r !eto (C3*50*90- C3*50*0- C3*50*>0- an C3*50*30)%ASee

te electronic version o' te Lournal 'or a color version o' tis 'igure%B%

narro$er% n te oter an- $en tere $ere not enoug sur'ac*tants

to ee" te nano"articles se"arate- 'ractal aggregates coul be

'or!e $it a $ie si;e istribution A2>B% 7s suc- as te con*tent o'

citric aci ecrease in te 'inal "roucts- te si;e istribu*tion o' te

nanoclusters $oul beco!e broaer% Due to tese t$o e''ects- te si;e

istribution o' te 'inal sa!"les oes not ave a si!"le correlation $it

te content o' citric aci sur'actant coating%
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8/11

3%3% =n'luence o' "ost*sntesis coating $it citric aci on !agnetic

beavior

e in'luence o' "ost*sntesis coating $it citric aci at 90 ,C inte 3r !eto (t$o*ste" "rocess) on te !agnetic beavior o' tenano"articles $as investigate on t$o ins o' uncoate iron o+ienano"articles $it i''erent si;es o' 9 n! (59) an 2> n! (52>)% 7seter!ine 'ro! EM i!ages ( :ig% 4a an b)- te iron o+ie core

si;es o' te citric*aci coate sa!"les C3*59*90 an C3*52>*90 $ere

still aroun 9 n! (!ean si;e o' sa!"le 59) an 2> n! (!ean si;e o'sa!"le 52>)- res"ectivel% =t inicates tat te sur'actant coating inot inuce signi'icant cange o' te nano"article core si;es% e!agnetic beaviors o' te sa!"les $ere !easure using te VSM atroo! te!"erature- as so$n in :ig% 4c an % e saturation

!agneti;ation (Ms) 'or te iron o+ie cores o' te citric aci coate

sa!"les C3*59*90 an C3*52>*90 $as eter!ine to be >0 e!u&g

an 4 e!u&g- al!ost te sa!e as te Ms o' te corres"oning

uncoate iron o+ie nano"articles 59 (>1 e!u&g) an 52> (4 e!u&g)-

res"ectivel% e are less tan
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,% ,i et al% & Microelectronic Engineering 110 (2013) 329334 333

:ig% 4% EM i!ages an VSM results o' citric aci coate iron o+ie nano"articles $it core si;es o' 9 n! an 2> n! in 3r !eto% (a an b) EM i!ages o' (a) C3*59*90 an

(b) C3*52>*90% (c an ) VSM results o' (c) C3*59*90 an () C3*52>*90% e insets in (c) an () are te corres"oning !agni'ie vie$s o' te M6 loo"s in te lo$ !agnetic 'iel%

te Ms 'or bul :e34 (92 e!u&g) an te Ms 'or bul c*:e23 (4

e!u&g) A30B- but are co!"arable to te e+"eri!ental values 'or M so'

!agnetite nano"articles s"anne te 30>0 e!u&g range A31B% e

insets in :ig% 4can $ere te corres"oning !agni'ievie$s o' teM6 loo"s in te lo$ !agnetic 'iel% ?ot o' te un*coate sa!"le 59

an te citric*aci coate sa!"le C3*59*90 is*"lae a

su"er"ara!agnetic beavior $it negligible coercivit% e coercivit

o' uncoate sa!"le 52> an citric*aci coate sa!*"le C3*52>*90

$as 4 e an 3F e- res"ectivel% e coercivit ecrease o' 52>

a'ter coate $it citric aci coul be attribute to te increase

istance bet$een te nano"articles cause b cit*ric*aci coating-

$ic le to te reuction o' te inter*"article i*"olei"ole interaction

an tus s!aller coercivit A23B% :or iron o+ie nano"articles $it si;e

s!aller tan 20 n!- te ter!al en*erg overco!es te i"olei"ole

interaction- an te ter!al 'luctuations can cange te irection o'

!agneti;ation o' te entire crstal% A32B us- te uncoate 9*n!

nano"articles in sa!"le 59 e+ibit a su"er"ara!agnetic beavior $it

no coercivit at roo! te!"erature% Even toug te citric*aci coating

can increase te istance bet$een te nano"articles an reuce teinter*"article i"olei"ole interaction- te su"er"ara!agnetic nature

o' te 9 n! nano"articles oes not cange an tus te coercivit o'

te citric aci coate sa!"le C3*59*90 stas to be ;ero% ere'ore-

te citric*aci coating i not alter te su"er"ara!agnetic beav*ior o'

te iron o+ie nano"article $it si;e close to 9 n!- an coul reuce

te coercivit o' iron o+ie nano"articles $it si;e close to 2> n!%

4% Conclusion

is stu e!onstrates te e''ect o' te sntesis conitions

incluing te aition o' citric aci an te coating te!"erature on te

"ro"erties o' citric*aci coate iron o+ie nano"articles%

e core si;es o' te citric*aci coate nano"articles coul be a*

juste 'ro! aroun n! to 13 n! b aing te citric aci at i'*'erent

stage in te sntesis "rocess# "re*aition into 'errous an 'erric

solution (1st !eto)- "ost*aition $en nano"articles "reci"itate

(2n !eto)- an "ost*sntesis coating a'ter un*coate nano"article

sntesi;e in a t$o*ste" "rocess (3r !et*o)% =n te t$o*ste"

"rocess 'or sntesis- te ecrease coating te!"erature resulte in

increase rona!ic si;es o' te sn*tesi;e citric*aci coate

nano"articles% us- te in'luences o' te aition o' citric aci an te

coating te!"erature on te si;e o' te 'inal "roucts $ere reveale%

:or te s!all si;e ( 9 n!) uncoate iron o+ie nano"articles $it a

su"er"ara!agnetic beavior- te citric*aci coating $oul not a''ect its

su"er"ara*!agnetic 'eature% :or te larger si;e ( 2> n!) iron o+ie

nano*"articles $it coercivit- te citric*aci coating $oul ecrease

teir coercivit% is $or inicates te sntesis conitions coul be

a""ro"riatel controlle to 'abricate te citric*aci coate nano"articles

'or a s"eci'ic "ur"ose%

7cno$leg!ents

is $or $as su""orte b te See 'uning rogra! 'or ?asic

@esearc 'ro! te 5niversit o' 6ong .ong- te @KC*K@: Krant

(6.5 049&11)- an 5niversit Krants Council o' 6ong .ong (con*

tract no% 7oE&*04&0F)% e are tan'ul 'or te "roo'reaing o' our

!anuscri"t b Cris @oberts%

@e'erences

[1 S% agner- =nvestigative @aiolog 3 (2002) 1%

[2 =% 6ilger- .% :rau'- % 7nrN- @% 6iergeist- @% 6ergt- %7% .aiser-7cae!ic @aiolog 9 (2002) 19F202%

[3 K% ,i- S% Sun- @%L% ilson- @%,% ite- 8% our!an- S%O% ang- Sensorsan 7ctuators 7# sical 12 (200) 9F10%[4 V%.% Varaan- D%,%:% Cen- L% Oie- ile- 200F%
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[5 7%.% Ku"ta- M% Ku"ta- ?io!aterials 2 (200>) 399>4021%

[6 L% Oie- L% 6uang- O% ,i- S% Sun- O% Cen- Current Meicinal Ce!istr 1(2009) 12F1294%

[7 .% oo- L% 6ong- S% Coi- 6%% ,ee- L%% 7n- C%S% .i!- S%% ,ee-Ce!istr o' Materials 1 (2004) 2F142F1F%

[8 /% ,u- /% /in- ?%% Maers- /% Oia- 8ano ,etters 2 (2002) 1F31F%

[9 % u- P% 6e- C% Liang- 8anoscale @esearc ,etters 3 (200F) 3941>%

[10 E% arton- @% De al!a- K% ?orgs- Soli State ecnolog >0 (200) 4%

[11 @% eissleer- ?%D% @oss- 7% @ee!tulla- S%S% Ka!bir- Molecular=!aging# rinci"les an ractice- eo"leQs Meical ublising 6ouse- 2010%

[12 S% 8iga!- .% ?aric- D% ?aaur- Lournal o' Magnetis! an MagneticMaterials 323 (2011) 23243%

[13 C% ?oer- M%@% ittaer- V% ?ul!us- L% ,iu- %% Davis- 8K 7sia Materials2 (2010) 2330%

[14 E% Munnier- S% Coen*Lonatan- C% ,inassier- ,% Dou;iec*Erolles- 6%Marcais- M% SoucR- .% 6ervR- % Dubois- =% Cour"a- =nternational Lournal o'ar!aceutics 33 (200F) 101%

[15 .%D% ani- @% .itture- 7% 7!e- 7%S% Couari- S%L% .o""iar- S%8% .ale-@% .aul*Kanear- Lournal o' ?ionanoscience > (2011) >9>%

[16 M%7% Daniele- M%,% Saugness- @% @oeer- 7% Cilress- /%% ?anera-S% :oulger- 7CS 8ano (2012) 203213%

[17 L%% :ortin- :% Ka;eau- C% ilel!- Euro"ean ?io"sics Lournal 3 (200F)223 22F%

[18 ,% ,i- .% Ma- C% ,eung- .% Can- % Can- % ong- % ong- =EEEransactions on Magnetics 4F (2012) 32993302%

[19 7% ,a"resta*:ernne;- % Doussineau- S% Dut;- :% Steiniger- 7%L% Moro-K%L% Mor- 8anotecnolog 22 (2011) 41>>01%

[20 C% ,iu- % 6uang- Soil Science Societ o' 7!erica Lournal 3 (1999) >2%

[21 7% ?ee- @% Massart- S% 8eveu- Lournal o' Magnetis! an MagneticMaterials 149 (199>) 9%

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[23 7% o!itaa- % .osi- S% 6atsugai- % /a!aa- /% ae!ura- Lournal o'Magnetis! an Magnetic Materials 323 (2011) 139F1403%

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[25 @%7% :ri!"ong- L% Dou- M% ecan- L%% 6ilt- Lournal o' Magnetis! anMagnetic Materials 322 (2010) 32331%

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[27 C%S%S%@% .u!ar- Micro'luiic Devices in 8anotecnolog# 7""lications-Lon ile T Sons- 2010%

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[32 C%S%S%@% .u!ar- Magnetic 8ano!aterials- ile- 2009%

effect of synthesis conditions on properties citric acid_2

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