320-fold luminescence enhancement of [Ru(dpp) 3 ]Cl 2 dispersed on PMMA opal photonic crystals and highly improved oxygen sensing performance

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1 OPEN (214) 3, e29; ß 214 CIOMP. All rights reserved /14 ORIGINAL ARTICLE 32-fold luminesene enhnement of [Ru(dpp) 3 ]Cl 2 dispersed on PMMA opl photoni rystls nd highly improved oxygen sensing performne Pingwei Zhou 1, Donglei Zhou 1, Li To 1, Yongsheng Zhu 1,2, Wen Xu 1, Si Xu 1, Shoo Cui 1,2, Lin Xu 1 nd Hongwei Song 1 Ru omplexes ([Ru(dpp) 3 ]Cl 2 ) were spin oted on poly(methyl methrylte) (PMMA) opl photoni rystls (PhCs), nd,32-fold luminesene enhnement ws oserved ompred to tht on glss, whih is the lrgest luminesene enhnement of dye moleules y the modultion of three-dimensionl (3D) PhCs reported until now. The enhnement mehnism ws refully exmined nd it ws shown tht the luminesene of [Ru(dpp) 3 ]Cl 2 depended on the moleule onentrtion nd temperture. It n e onluded tht the suppressed non-rditive relxtion mong the moleules nd the field enhnement oth ontriute signifintly to the luminesene enhnement. The PMMA PhC/Ru omplex omposites were then tested for their intrellulr oxygen sensing nd ell imging properties; these omposites effetively improved the limit of detetion (LOD) nd the rightness of the ell imges. (214) 3, e29; ; pulished online 1 Otoer 214 Keywords: ell imging; fluoresene enhnement; oxygen sensing; photoni rystls INTRODUCTION Luminesene sensing nd imging is urrently one of the most widely used tehniques for environmentl monitoring, disese dignosis nd genomi/proteomi reserh. 1 In most ses, the prtil pplition requires tht the luminesene sensing is performed with weker pumping light; therefore, luminesene enhnement hs profound signifine for otining higher sensitivity nd lower limit of detetion (LOD). Until now, vrious methods hve een explored to enhne the luminesene intensity during luminesene sensing, inluding optil fier sensing, surfe-plsmon-indued luminesene enhnement nd the modultion of photoni rystls (PhCs). 2 4 Among the vrious tehniques relted to luminesene enhnement, the modultion of PhCs hs ttrted onsiderle interest nd hs yielded wide vriety of pplitions PhCs n lrgely enhne the luminesene of dyes/quntum dots, nd through theoretil simultion, the exittion field n e lrgely enhned. 14,15 In prtiulr, not only n three-dimensionl (3D) opl or inverse opl PhCs lrgely enhne the luminesene of dyes ut they lso hve the dvntge of esier preprtion. As reported y Song s group, 16,17 4-fold enhnement in luminesene ws oserved using 3D PhCs for optil storge, nd 162-fold enhnement ws otined y modulting dul stopnd PhCs. As reported y Li s group, fold enhnement ws lso oserved using 3D PhCs. In most of these ses, luminesene enhnement ws ttriuted to the exittion field enhnement effet. Although the exittion field n e enhned y 3D PhCs through theoretil simultion, 19 the prtil proess of luminesene enhnement is more omplex, nd the essentil mehnism should e further disussed to otin more signifint enhnement. In this work,,32-fold enhnement ws oserved sed on the oupling of [Ru(dpp) 3 ]Cl 2 with 3D poly(methyl methrylte) (PMMA) opl PhCs, whih is the lrgest enhnement using 3D PhCs until now. The enhnement mehnism ws determined sed on the emissions of [Ru(dpp) 3 ]Cl 2 on dye onentrtion dispersed on the PMMA PhCs nd temperture. The PMMA PhC/Ru omplex omposites were lso used for ssistnt intrellulr oxygen sensing nd ell imging, whih effetively improved the LOD nd the rightness of the ell imges. MATERIALS AND METHODS Preprtion of PMMA PhCs The PMMA spheres were synthesized following the steps elow. 2 First, methyl methrylte (MMA) ws wshed with NOH solution (.1 g ml 21 ) to remove the polymeriztion inhiitor. 21 Seond, 3-mL MMA solution nd 4-mL deionized wter were pled into three-neked ottle. Polymeriztion ws performed y oil th heting t 9 6C for 1.5 h with mgneti stirring nd 18-mg of potssium persulfte s n inititor. Finlly, the milk white solution with suspended PMMA spheres ws otined. By hnging the mount of MMA solution in the ove reipe, the dimeter of PMMA spheres ould e perfetly tuned. By vrying the MMA solution mount from 2.7-mL to 3.4-mL in.1-ml steps, spheres of different sizes were otined. 1 Stte Key Lortory on Integrted Optoeletronis, College of Eletroni Siene nd Engineering, Jilin University, Chnghun 1312, Chin nd 2 College of Physis, Jilin University, Chnghun 1312, Chin Correspondene: Professor HW Song, College of Eletroni Siene nd Engineering, Jilin University, 2699 Qinjin Street, Chnghun 1312, Chin E-mil: songhw@jlu.edu.n Reeived 18 April 214; revised 21 July 214; epted 22 July 214

2 2 PMMA opl PhCs for optil oxygen sensing PMMA PhCs were synthesized through the vertil deposition method y growing the PMMA spheres onto the glss sustrte. 22 First, 6-mL deionized wter nd 3-mL of the preursor solution were prepred efore eing pled into 1-mL plsti eker. Seond, hydrophili glss sustrte ws vertilly inserted into the plsti eker. The solution ws nturlly evported in drying oven t 32 6C for 24 h, nd the PMMA spheres self-ssemled on the glss sustrte through hydrophili intertions. Finlly, the PhCs were pled into the drying oven t 12 6C for 4 min to improve their physil stility. Additionlly, the stopnd of the PhCs ws finely ontrolled vi the dimeter of the PMMA spheres, whih rnged from 39 to 625 nm in dimeter. Luminesene mesurement The [Ru(dpp) 3 ]Cl 2 (Sigm-Aldrih Corportion, Sint Louis, MO, USA) ws dissolved in ethnol solution with onentrtion of.4 mg ml 21. Then, 6-mL of the solution ws spin-oted onto the PhCs nd the glss (15 r.p.m., 2 s). The spetr of [Ru(dpp) 3 ]Cl 2 were mesured using onfol lser snning mirosope with n exittion light t 455 nm. Cytotoxiity The ytotoxiity of the PMMA PhCs ws determined y the following experiments. Humn rest ner ells (MCF-7, suspended) were ultured in Duleo s modified Egle s medium supplemented with 1% fetl ovine serum t 37 6C in 5%-CO 2 inutor. PMMA PhCs on the glss sustrte (2 m 2 piee 21 ) were prepled t the ottom of 12-well plte through ultrviolet irrdition. Then, 1-mL of n MCF- 7 ell suspension ( ells ml 21 ) ws seeded per well nd exposed to PMMA PhCs, nd the ells were inuted for dditionl periods rnging from 2 to 24 h. Untreted ells were used s ontrol (1% viility). At the end of the exposure, 2-mL of the ell suspension ws removed nd mixed with the sme volume of.4%- trypn-lue solution. Following ell stining for 2 min, n liquot (1 ml) of the stined ell suspension ws pipetted onto hemoytometer nd ounted for the ell numer. Finlly, the otined ell viility ws expressed reltive to the ontrol. Oxygen sensing of the MCF-7 ells [Ru(dpp) 3 ]Cl 2 t onentrtion of 2 mg ml 21 ws inuted together with MCF-7 ells in hmer slides t 37 6C for 12 h under 5%-CO 2 gs. The glss with PMMA PhCs nd pure glss were pled into the onfol dish. Then,.5-mL of the MCF-7 ell suspension ws dded to the PMMA PhC nd glss surfes. Gs with different oxygen onentrtions ws piped into the onfol dish, nd seling film ws used to rete n independent environment. The MCF-7 ells were viewed in vitro with onfol lser snning mirosope under ontinuous pumping of 455-nm lser. RESULTS AND DISCUSSION Struturl fetures PhCs possess sptil periodiity in their dieletri onstnts on the length sle of the optil wvelength. Consequently, PhCs respond to eletromgneti wves in similr wy to how tomi rystls respond to eletrons. Beuse n eletroni nd gp is reted y the periodi rrngement of toms in semiondutor, the periodi eletromgneti modultion reted y the PhCs n yield PSB (photoni stopnd), nd of frequeny for whih light propgtion in the PhCs is foridden. The PhCs prepred with different sizes of PMMA spheres n exhiit different sptil periodiities in their dieletri onstnts nd yield different PSBs. Figure 1 shows the trnsmission spetr of the PhCs with different stopnds, nd the inset of Figure 1 shows the reltionship etween the PSB nd the dimeter of PMMA spheres. The PSB positions were well desried y the Brgg diffrtion 23 eqution using the PMMA sphere dimeters mesured y SEM (snning eletron mirosope). Figure 1 nd 1 shows the SEM imge nd side-view imge of PhC with PSB t 455 nm. The PMMA spheres yielded long-rnged ordered struture, 8 6 Stopnd (nm) 6 5 Trnsmission (.u.) Dimeter (nm) 1 mm 2 1 mm Wvelength (nm) Figure 1 () Trnsmission spetr of the PhCs with different stopnds. Inset: the reltionship etween the PSB nd the PMMA sphere dimeter. () SEM imge of PhC with PSB t 455 nm. () Side-view imge of PhC with PSB t 455 nm. PhC, photoni rystl; PMMA, poly(methyl methrylte); PSB, photoni stopnd; SEM, snning eletron mirosope.

3 PMMA opl PhCs for optil oxygen sensing 3 suggesting the formtion of well-orgnized PhCs. As presented in Figure 1, the PhC thikness ws pproximtely 1 mm, nd the PhC struture ws omposed of pproximtely 4 lyers of PMMA spheres. The reltive mount of [Ru(dpp) 3 ]Cl 2 moleules on the PhC/ glss smples To ensure the sme density of the [Ru(dpp) 3 ]Cl 2 moleules on the PhC nd the glss, the sme 6-mL solution of [Ru(dpp) 3 ]Cl 2 moleules (.4 mg ml 21 ) ws tken nd spin-oted onto the PhC nd the glss. Beuse the mount of solution ws smll nd the rottion speed of the spin oter ws slower, fter spin-oting, the thin film of [Ru(dpp) 3 ]Cl 2 moleules ws distriuted within irle re, nd no solution ws spin-oted outside the smples. The res of the PhC smple nd the glss smple were determined to e 1.33 m 2 nd 1.54 m 2, respetively. To verify the homogeneity of the two smples, five points were rndomly hosen from the irles (Supplementry Fig. S1) of the two smples, nd the luminesene intensity of eh point ws mesured. The luminesene intensity rrely hnged, inditing tht the [Ru(dpp) 3 ]Cl 2 moleules were distriuted uniformly. The res of the irles on the PhC nd the glss were nerly the sme, inditing tht the numer of [Ru(dpp) 3 ]Cl 2 moleules t eh point ws similr. To further determine the numer of [Ru(dpp) 3 ]Cl 2 moleules, the sorption spetr of [Ru(dpp) 3 ]Cl 2 on the glss nd on the PhCs were mesured nd ompred, s shown in Figure 2. The red line shows the sorption spetrum of the PhC with PSB t 41 nm, nd the lk line shows the sorption spetrum of the sme PhC oted with [Ru(dpp) 3 ]Cl 2 moleules. To distinguish the sorption oeffiient of [Ru(dpp) 3 ]Cl 2, the PSB of the PhC ws hosen fr from the sorption of [Ru(dpp) 3 ]Cl 2. The sorption of the PhC rnging from 45 to 5 nm improved fter eing oting with [Ru(dpp) 3 ]Cl 2 moleules, whih suggests tht the [Ru(dpp) 3 ]Cl 2 moleules suessfully dhered to the PhC surfe. The sorption oeffiient of [Ru(dpp) 3 ]Cl 2 on the PhC ws determined y sutrting the red line from the lk line nd is presented in the Figure 2 inset (red dots). The lk dots disply the sorption spetrum of [Ru(dpp) 3 ]Cl 2 on glss. As indited in the Figure 2 inset, the sorption strength of [Ru(dpp) 3 ]Cl 2 on the PhC ws very lose to Asorption (.u.) Asorption (.u.) PhC PhC+Ru Wvelength (nm) Wvelength (nm) Figure 2 Asorption spetr of the lnk PhC (red) nd the PhC oted with [Ru(dpp) 3 ]Cl 2 (lk). Inset: omprison of the sorption spetr of [Ru(dpp) 3 ]Cl 2 oted on the glss (lk) nd on the PhC (red). PhC, photoni rystl. tht on the glss, inditing tht the numer of [Ru(dpp) 3 ]Cl 2 moleules on the PhC ws nerly identil to tht on the glss. Notly, in the present PMMA PhC/[Ru(dpp) 3 ]Cl 2 omposites, the distriution of [Ru(dpp) 3 ]Cl 2 moleules in the PMMA PhCs ws not homogeneous. To determine the distriution of the moleules, the depth-dependent luminesene intensity ws mesured using onfol lser snning mirosopy (Supplementry Fig. S2). It n e onluded tht the moleule density grdully deresed with the depth of the PMMA PhCs. This suggests tht most of the dye moleules distriuted on the PMMA PhC surfe. 32-fold luminesene enhnement nd its mehnism The emission spetr of [Ru(dpp) 3 ]Cl 2 on the PhC nd on the glss were mesured y onfol lser snning mirosopy under n exittion light t 455 nm. As shown in Figure 3, the luminesene intensity of [Ru(dpp) 3 ]Cl 2 oted on the PMMA PhCs ws muh stronger thn tht oted on the glss; even the luminesene of [Ru(dpp) 3 ]Cl 2 ws enhned 1 times. The luminesene enhnement ftor, whih is defined s the rtio of the luminesene intensity of [Ru(dpp) 3 ]Cl 2 oted on the PMMA PhCs to tht on the glss, ws determined to e s high s,32-fold. The inset of Figure 3 displys the digitl photogrph of the empty glss (right), [Ru(dpp) 3 ]Cl 2 oted on the glss (middle) nd [Ru(dpp) 3 ]Cl 2 oted on the PhC (left) under xenon lmp exposure, whih further indites the highly improved red emissions of [Ru(dpp) 3 ]Cl 2 on the PhC. To revel the mehnism of luminesent enhnement, the originl solution ws diluted with solute ethyl lohol with different onentrtions. Figure 3 nd 3 shows the dependene of the enhnement ftor nd dey time onstnt on the onentrtion of [Ru(dpp) 3 ]Cl 2 moleules. Interestingly, the enhnement ftor inresed grdully with the inresed onentrtion from more thn 1 times to 32 times. Notly, when the onentrtion ws lower thn 3 mg ml 21, the hnge ws rpid nd when the onentrtion ws higher thn this vlue, the hnge ws not ovious. The dey time onstnt of [Ru(dpp) 3 ]Cl 2 on the glss rpidly deresed with the inresed [Ru(dpp) 3 ]Cl 2 onentrtion, rnging from 8 to 3 mg ml 21 nd nerly reserved s onstnt s the onentrtion inresed further. The derese in the dey time onstnt on the moleule onentrtion ws ttriuted to the energy trnsfer (ET) mong the different moleules. When the moleule onentrtion ws lower, the moleules distriuted freely on the glss, nd the ET mong different moleules ws diffiult. As the moleule onentrtion inresed, the ET mong different moleules inresed due to the deresed verge distne of the nery moleules, nd the dey time onstnt deresed with the inresed moleule onentrtion. As the onentrtion of moleules ws high enough, the moleules on the glss were lustered together, nd the ET mong different moleules ws the sme, leding to the stedy dey time onstnts. By ontrst, the dey time onstnt of [Ru(dpp) 3 ]Cl 2 on the PhC ws pproximtely 4.1 ms nd rrely hnged with the onentrtion, inditing tht the PhC struture effiiently restrined the ET mong different moleules. Owing to the huge surfe re, the PhC ould effetively disperse the [Ru(dpp) 3 ]Cl 2 moleules, preventing the ET mong the dye moleules. Additionlly, the dey time onstnt of [Ru(dpp) 3 ]Cl 2 on the PhC inresed to pproximtely 2 4 times tht on the glss, depending on the onentrtion of [Ru(dpp) 3 ]Cl 2. This finding my e minly ttriuted to modultion of the effetive refrtive index on the rditive dey rte nd the existene of solid skeleton on the non-rditive relxtion rte of [Ru(dpp) 3 ]Cl 2 on the PhC. In most of the previous pulitions relted to quntum dots or dye moleules

4 4 PMMA opl PhCs for optil oxygen sensing s es s es Dey time (ms) Enhnement ftor Wvelength (nm) Conentrtion (mg ml -1 ) Figure 3 () Spetr of [Ru(dpp) 3 ]Cl 2 on the PhC (lk) nd on the glss (red). Inset: digitl photogrph of [Ru(dpp) 3 ]Cl 2 on the PhC (left), [Ru(dpp) 3 ]Cl 2 on the glss (middle), nd the glss (right). () The enhnement ftor. () Dey time of [Ru(dpp) 3 ]Cl 2 on the PhC (lk) nd on the glss (red), with different onentrtions. PhC, photoni rystl. inserted into 3D PhCs, n ovious hnge in the dey time onstnt ws oserved. 7,8 To verify the universlity of the PMMA PhC modultion of the dye moleules, the luminesene enhnements for different dyes dispersed on the PMMA PhCs were studied nd re presented in Figure 4. When the moleule onentrtion ws fixed t.1 mg ml 21, n 84-fold luminesent enhnement ws oserved for FITC, wheres 23-fold enhnement ws oserved for R6G. It ws lso ovious tht for the sme dye, the enhnement ftor t higher onentrtion (.1 mg ml 21 ) ws muh higher ompred with tht t lower onentrtion (2 mg ml 21 ). Beuse the surfe re of the PhC is muh lrger thn tht of the glss, the moleules n e well dispersed nd the ET etween dye moleules n e lrgely Enhnement ftor Lower onentrtion Higher onentrtion FITC R6G [Ru(dpp) 3 ]Cl 2 Figure 4 The enhnement ftor of FITC, R6G nd [Ru(dpp) 3 ]Cl 2 t lower/ higher onentrtion. restrined. The enhnement of exittion field should not vry signifintly when different dye moleules re oted on the PhCs when mesured t the sme onditions. However, different enhnement ftor ws otined for different dye moleules. This finding demonstrtes tht the luminesene enhnement ws otined for vrious dye moleules nd tht the enhnement ftor depended on not only the enhned exittion field, ut lso the type of dye moleules. This result my e ttriuted to the hnged virtion onds, the vried ET rte nd the vrint polrity of the dye moleules. Indeed, s the polrity of the dye moleules hnges, the dye moleule intertion with the PhC skeleton would lso hnge, whih would most likely influene the luminesent quntum yield. Notly, the highly enhned luminesene of the dye moleules n e otined not only y the modultion of 3D PhCs, ut lso y the sttering of some prtiles. Previously, some sttering prtiles, suh s TiO 2, 24 were dded to sensor films to mke the exittion light hit more emitters nd the emission light stter k to the detetor. 25 This is lso n effetive strtegy to improve the exittion of the oxygen-sensitive proe nd enhne the signls. To verify the PhC effet, the PhC smples with different PSBs (39, 455, 55 nd 625 nm) nd film smple without PSB (omprising PMMA spheres with different sizes) were prepred. Figure 5 shows the spetr of [Ru(dpp 3 )]Cl 2 on different smples, nd Figure 5 shows the luminesent enhnement ftor of different smples. The luminesene intensity of [Ru(dpp 3 )]Cl 2 on the glss ws reltively low, nd with different strutures omposed of PMMA spheres, the luminesene intensity of [Ru(dpp 3 )]Cl 2 ws enhned t different levels. When using the film without PSB or the PhCs with PSB fr from the exittion light (455 nm), the enhnement ftor vried from 12 to 164 (Figure 5, right). In these situtions, the exittion light ws sttered y PMMA spheres nd hit more [Ru(dpp 3 )]Cl 2 moleules. When using the PhC with PSB right oupled with the exittion light, the enhnement ftor ws improved to 32-fold

5 PMMA opl PhCs for optil oxygen sensing nm PhCs 455-nm PhCs 545-nm PhCs 625-nm PhCs Glss No stopnd 39-nm PhCs 455-nm PhCs 545-nm PhCs 625-nm PhCs No stopnd Enhnement ftor Wvelength (nm) 12 Figure 5 The spetr (left) nd enhnement ftor (right) of [Ru(dpp) 3 ]Cl 2 on PhCs with different stopnds nd on the PMMA film without stopnd were ompred to tht on glss. PhC, photoni rystl; PMMA, poly(methyl methrylte). (Figure 5, right). In this sitution, the exittion light oupled with the PhC struture nd the sttering ws further improved due to the modultion through the periodi dieletri onstnt. This shows tht the existene of PSB leds to n extr luminesene enhnement of,2 times. We stimulted the integrted eletri field distriution on the depth of the PMMA PhCs y the FDTD (finite differene time domin) method, nd the result showed tht on the surfe of the PhC, the integrted eletri field improved y pproximtely two times in omprison with the position without PSB modultion (Supplementry Fig. S3). As mentioned ove, in the reent smple, most of the dye moleules distriuted on the surfe of the PMMA rystls; therefore, the experimentl luminesene enhnement is in ordne with the theoretil stimultion. Temperture-dependent luminesene nd dynmis Temperture-dependent luminesene nd dynmis is ritil for determining the rditive nd non-rditive trnsition proesses. Figure 6 shows the totl luminesene intensity of [Ru(dpp) 3 ]Cl Temperture (K) Temperture (K) Nonrditive rte (ms 1 ) τ 1 (ms 1 ) Figure 6 Luminesene intensity (), reiprol of the dey time nd the fitting line (red) () nd the non-rditive rte of [Ru(dpp) 3 ]Cl 2 on PhC (lk) nd [Ru(dpp) 3 ]Cl 2 on glss (lue) () with different tempertures. PhC, photoni rystl.

6 6 PMMA opl PhCs for optil oxygen sensing O 2 % 1% 2% 3% 5% 1% 15% 2% Slope=14.2 Slope= I /I Wvelength (nm) O 2 onentrtion (1 %). 1 d O 2 onentrtion (1 %) O 2 onentrtion (1 %) 4 Figure 7 () Emission spetr of [Ru(dpp) 3 ]Cl 2 on the PhC with different oxygen onentrtions. () (I /I21) of [Ru(dpp) 3 ]Cl 2 on the PhC (lk dots), glss (lue dots) nd fitting line (red line). (, d) Luminesene intensity of [Ru(dpp) 3 ]Cl 2 with different oxygen onentrtions on the PhC nd on the glss. PhC, photoni rystl. on the PhC nd on the glss s funtion of temperture under 455- nm exittion. It is ovious tht the luminesene intensity of [Ru(dpp) 3 ]Cl 2 on the glss deresed rpidly with the inresed temperture, ut on the PhC, the luminesene intensity rrely hnged with the temperture. This indites tht the temperture quenhing of [Ru(dpp) 3 ]Cl 2 n e suppressed onsiderly on the PhC. As is well estlished, the non-rditive trnsition of dye moleules stems from moleule virtion, whih inreses quikly with elevted temperture, induing temperture quenhing of the luminesene. Beuse the dye moleules were dispersed into the gps of the PMMA PhCs, the moleule virtion ould e effetively limited due to the frmework of the PMMA solid. To further determine the rditive nd non-rditive relxtion rtes in different smples, the temperture dependene of the reverse of the dey time onstnt of [Ru(dpp) 3 ]Cl 2 on the PhC nd on the glss re presented in Figure 6. As is well known, the non-rditive relxtion rte improves gretly with inresed temperture due to highly improved moleule virtion. Compred with the non-rditive relxtion rte, the hnge of rditive trnsition rte for the emitters is not ovious. Bsed on the multi-phonon-relxtion theory, the totl [Ru(dpp) 3 ]Cl 2 dey rte (the reverse of the dey time, designted s W Totl ) n e written s follows: 26 W Totl ~W R zw NR ðþ1{e ð1þ {DE=hv where W R is the rditive trnsition rte nd W NR () is the non-rditive relxtion rte t K. Through the lultion, W R ws determined to e ms 21 on the glss nd 92.3 ms 21 on the PhC. W NR () ws determined to e ms 21 on the glss nd

7 PMMA opl PhCs for optil oxygen sensing ms 21 on the PhC. Aording to the theory of the virtul-vity model, the rditive trnsition rte n e written s follows: 27 1= 3 n 2 2neff eff z2 W R &f ðedþ ð2þ where f(ed) is the eletri dipole strength nd n eff is the effetive refrtive index of the medium. The n eff of the PhC smple nd the glss smple re 1.15 nd 1.27, respetively. Through Eqution (2), W R on the glss is pproximtely 1.38 times tht on the PhC, whih is in ordne with the experimentl dt. It is ovious tht the W NR () of [Ru(dpp) 3 ]Cl 2 ws restrined lrgely with the ssistne of PMMA PhC in ontrst with tht on the glss, nd the dependene of the nonrditive rte of [Ru(dpp) 3 ]Cl 2 on temperture ws lulted y Eqution (1) nd is presented in Figure 6. Using the W R nd W NR vlues lulted ove, the internl quntum effiieny of [Ru(dpp) 3 ]Cl 2 on the PhC (g PhC) nd on the glss (g glss ) s funtion of temperture ws determined. At room temperture, g PhC 568.6% nd g glss 512.8%. It is surprising tht the internl quntum effiieny improves 5.36-fold due to lrgely restrined non-rditive relxtion. Beuse of the introdution of the PhC solid skeleton, the non-rditive relxtion n e lrgely l 2 restrined 28,29 nd similr phenomenon ws lso oserved in rre erth ions inserted in inverse opl PhCs. 3 Additionlly, the influene of photolehing ws lso onsidered nd n e ignored due to the short mesurement time (Supplementry Fig. S4). Overll, 32-fold enhnement ws oserved sed on the oupling of [Ru(dpp) 3 ]Cl 2 with 3D PMMA PhCs. In ddition to the exittion field modultion, the suppression of ET etween [Ru(dpp) 3 ]Cl 2 nd non-rditive trnsition of the dye moleules dispersed on the PMMC PhCs lso plyed n importnt role in the luminesene enhnement. Highly improved oxygen sensing properties Bsed on this 32-fold enhnement, the gseous oxygen sensing, intrellulr oxygen sensing nd ell imging properties of [Ru(dpp) 3 ]Cl 2 were studied with the ssistne of PMMA opl PhCs. In trditionl gseous oxygen sensing, the luminesene spetr of the dye with different oxygen onentrtions re displyed in Figure 7. Aording to the spetr, the luminesene intensity of [Ru(dpp) 3 ]Cl 2 on PhC grdully deresed with the inresed oxygen onentrtion. This oxygen optil sensing sheme is sed on the quenhing of [Ru(dpp) 3 ]Cl 2 y moleulr oxygen, so the luminesene intensity n e desried y the Stern Volmer expression. d 2.5 With PhC With PhC 12 Without PhC Without PhC 2. 1 I /I Slope=13.54 Slope= O 2 onentrtion (1%) O 2 onentrtion (1%) 2 Figure 8 Confol imge of the MCF-7 ells on the PhC () nd on the glss (), respetively. ()(I /I21) of [Ru(dpp) 3 ]Cl 2 on the PhC (lk dots), glss (lue dots) nd fitting line (red line). (d) The luminesene intensity of [Ru(dpp) 3 ]Cl 2 in MCF-7 ells with different oxygen onentrtions on the PhC (lk dots) nd on the glss (lue dots), respetively. PhC, photoni rystl.

8 8 PMMA opl PhCs for optil oxygen sensing Figure 7 shows the highly liner reltionship etween (I /I21) nd the oxygen onentrtion. The sensitivity (I /I 2 ) ws determined to e 3.8 for the PhC smple nd 3.3 for the glss smple. The non-rditive relxtion n e lrgely restrined due to the introdution of PhC solid skeleton, nd more eletrons in the triplet exittion stte n e quenhed y oxygen, so the sensitivity of the PhC smple is higher thn tht of glss smple. It should e highlighted tht ompred with the other study on oxygen sensing using Ru(dpp) 3, the sensitivity of the PhC smple is not outstnding, ut the quntum effiieny of the PhC smple is the highest one (68.6%). Aording to Wng s review, 25 t low oxygen onentrtion, the signl hnge is mximl nd lmost liner. Figure 6 nd 6d shows the luminesene intensity of [Ru(dpp) 3 ]Cl 2 on the PhC nd on the glss, respetively nd it ws lmost liner when the oxygen onentrtion rnged from % to 3%. Through the lultion, the LOD (3S/N: S, stndrd devition; N, slope) 31 for oxygen on the PhC nd on the glss re 5 ppm nd 497 ppm, respetively. Interestingly, the smples of the [Ru(dpp) 3 ]Cl 2 on the PhC demonstrte muh lower LOD of oxygen thn tht on the glss. Figure 8 nd 8 displys the luminesene imges of MCF-7 ells in ir with nd without the ssistne of PMMA PhC, respetively. It is ovious tht with the ssistne of PMMA PhC, the luminesene imge of MCF-7 ells eme more distint nd right ompred with those without the ssistne of PMMA PhC. Beuse the [Ru(dpp) 3 ]Cl 2 moleules re dispersed in the ytoplsm nd the size of MCF-7 ells is pproximtely severl mirons, [Ru(dpp) 3 ]Cl 2 nd PMMA PhC hve fr-field intertions. In this sitution, PMMA PhC ted s reflet sustrte nd only 1.7-fold enhnement ws otined. Figure 8 shows the highly liner reltionship etween (I / I21) nd the oxygen onentrtion. The sensitivity (I /I 2 ) ws determined to e 3.4 for the PhC smple nd 3.5 for the glss smple. The sensitivity ws lmost the sme euse the intertion etween the oxygen nd [Ru(dpp) 3 ]Cl 2 moleules ws similr (oth in the ytoplsm). Figure 8d displys the luminesene intensity of [Ru(dpp) 3 ]Cl 2 in MCF-7 ells with different oxygen onentrtions on the PhC (lk dots) nd on the glss (lue dots), respetively. Through the lultion, the LOD for oxygen in MCF-7 ells is 6 ppm with the ssistne of PhC, whih is lower thn tht without the ssistne of PhC (11 ppm). In ddition, the ytotoxiity test ws onduted to verify the ioomptiility of the PMMA PhCs. Figure 9 shows the ell viility of PMMA PhCs on MCF-7 ells t vrious hours. It is evident Cell viility (%) Time (h) Figure 9 Cell viility of PMMA PhCs on MCF-7 ells t different hours. PMMA, poly(methyl methrylte). PhC, photoni rystl. tht the ell viility is over 9% fter 24 h, inditing tht the toxiity of the PMMA PhCs is miniml. In study 32 using polystyrene nnoprtiles loded with modified Ru(dpp) 3 s optil oxygen sensing proe, the sensing nd imging of intrellulr oxygen following two-photon exittion were suessfully hieved. The kground sorption nd luminesene of the iomtter eme weker through ner-infrred exittion. In the present work, we foused more on employing the PhC struture for oxygen sensing nd imging. Using unmodified [Ru(dpp) 3 ]Cl 2 s the proe, through the ssistne of PhC struture, 1.7-fold enhnement ws hieved for the ell imging rightness, nd intrellulr oxygen sensing t n oxygen onentrtion from % to 2% ws otined. Additionlly, the LOD ws improved through the ssistne of the PhC struture. CONCLUSIONS In summry, 32-fold enhnement ws oserved s [Ru(dpp) 3 ]Cl 2 ws spin-oted onto PMMA PhCs, whih is the lrgest enhnement using 3D PhCs until now. Its origin ws minly ttriuted to the suppression of ET etween [Ru(dpp) 3 ]Cl 2 moleules nd non-rditive trnsition nd the enhnement of the exittion field. 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