Design of Pyrrolic-N-rich Carbon Dots with. Absorption in the First Near Infrared Window for. Photothermal Therapy

Transcription

1 Supporting Information Design of Pyrrolic-N-rich Carbon Dots with Absorption in the First Near Infrared Window for Photothermal Therapy Fitri A. Permatasari, Hiromitsu Fukazawa, Takashi Ogi,*, Ferry Iskandar,, and Kikuo Okuyama Department of Chemical Engineering, Graduate School of Engineering, Hiroshima University, Higashi-Hiroshima , Japan Department of Physics, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Bandung 40132, Indonesia Research Center for Nanoscience and Nanotechnology, Institut Teknologi Bandung, Bandung 40132, Indonesia * Corresponding author: ogit@hiroshima-u.ac.jp S-1

2 Calculation of Photothermal Conversion Efficiency (η) The photothermal conversion efficiency was calculated based on previous report. 1 Details of the calculation are as follows. Consider the total energy balance for this system: dt dt mici Qin, CDs Qin, Qout (1) where m and C are the mass and heat capacity of each component (CDs and water), respectively. dt is the change in solution temperature with laser irradiation time. dt Q in, CDs is the photothermal energy input from light absorption by the CDs: Q in, CDs A I(1 10 ) (2) where I is the laser power, Aλ is the absorbance of the CDs at 655 nm (i.e., the laser wavelength), and η is the efficiency of the conversion of absorbed light energy to thermal energy. Q, is the heat input from light absorption by the oundings (i.e., water and the cuvette); in this was measured independently and found to be 6.4 mw. Q out is the thermal losses due to the natural convection: Q out ha T T ) (3) ( where h is the heat-transfer coefficient, A is the surface area of the cuvette, and T T is the difference between the temperatures of the solution temperature and oundings (air temperature). When the system reaches a steady state, the solution temperature reaches a maximum (T = Tmax); rearranging equations (1), (2), and (3) gives ha( Tmax T ) Qin, (4) I(1 10 ) A To obtain the ha value, assume a dimensionless parameter θ: S-2

3 T T T T (5) max Substituting equation (5) into equation (1), then rearranging equation (1) gives d ha dt mic i i Qin, ha T CDs ( max Q T in, ) (6) After the system reaches a steady state, the laser is switched off, off which means Q Q 0 (7) in, CDs in, Then, substituting equation (7) into equation (6) and rearranging equation (6) gives mici i d dt (8) ha Integrating equation (8) gives mici i t s ln() with s ha (9) The value of ha can therefore be calculated using the linear time data from the plot of the cooling time vs lnθ (Figure 5d). Substituting ha into equation (4) enables calculation of the photothermal conversion efficiency (η) of the CDs. Because the CD concentration is smaller than the water concentration, the water component is more dominant than the CD component: 2-4 τ s = m w C w ha (10) S-3

4 Figure S1. Preparation of CDs synthesized using various nitrogen sources. Molar ratio of citric acid:urea 1:5, temperature 140 C, 30 min. S-4

5 Figure S2. (a) Absorption spectra of CDs diluted 300-fold with ultrapure water. CDs were synthesized using various citric acid:urea molar ratios for 30 min at 140 C; (b) absorption spectra of CDs synthesized using citric acid:urea molar ratio of 1:1 for 30 min at 140 C; and (c) digital micrograph of CDs samples. S-5

6 Figure S3. (a) NIR peak stability of CDs synthesized using various citric acid:urea molar ratios for 30 min at 140 C; (b) NIR peak stabilities of CDs synthesized using citric acid:urea molar ratio of 1:5 at 140 C for various reaction times; and (c) NIR peak stabilities of CDs synthesized using citric acid:urea molar ratio of 1:5 for 30 min at various reaction temperatures. All absorption spectra were recorded within 5 d from synthesis. S-6

7 Figure S4. (a) Absorption spectra of CDs diluted 300-fold with ultrapure water, synthesized using citric acid:urea molar ratio of 1:5 at 140 C and various reaction times; (b) digital micrographs of CD samples (upper side: without UV exposure; lower side: under UV exposure at 365 nm); (c) absorption spectra of CDs diluted 300-fold with ultrapure water, synthesized using citric acid:urea molar ratio of 1:5 for 30 min at various temperatures; and (d) digital micrographs of CD samples. S-7

8 Figure S5. Full-scan XPS survey spectra of CDs-550 (absorption peak centered at 550 nm), CDs-650L (low absorption peak centered at 650 nm), and CDs-650 (high absorption peak centered at 650 nm). S-8

9 Table S1. Atomic percentage of CDs composition that extracted from the full scan XPS spectra. Sample C N O CDs % 2% 40% CDs-650L 49% 13% 39% CDs % 13% 32% Table S2. Deconvolution results for C1s spectra. Sample C C, C=C C N, C O C=N, C=O O=C O, O=C N CDs % 26% 8% 26% CDs-650L 49% 12% 7% 32% CDs % 12% 7% 29% Table S3. Deconvolution results for N1s spectra. Sample Pyridinic N Pyrrolic N Graphitic N CDs-550 2% 18% 80% CDs-650L 2% 64% 33% CDs-650 2% 71% 27% S-9

10 Figure S6. AFM phase imaging of samples: (a) CDs-550 (inset shows CD crystal structure); (b) CDs-650. S-10

11 Figure S7. Absorption spectra of CDs-650 for 5 d after synthesis. S-11

12 Figure S8. Digital images and photoluminescence spectra of 300-fold dilution: (a) CDs-650; (b) CDs-550. S-12

13 Figure S9. Molar extinction coefficient of CDs-650 at various CDs concentration. S-13

14 References (1) Roper, D. K.; Ahn, W.; Hoepfner, M. Microscale Heat Transfer Ttransduced by Surface Plasmon Resonant Gold Nanoparticles. J. Phys. Chem. C, 2007, 111, (2) Liu, Y.; Ai, K.; Liu, J.; Deng, M.; He, Y.; Lu, L. Dopamine-melanin Colloidal Nanospheres: an Efficient Near-infrared Photothermal Therapeutic Agent for In Vivo Cancer Therapy. Adv Mater., 2013, 25, (3) Li, D.; Han, D.; Qu, S.-N.; Liu, L.; Jing, P.-T.; Zhou, D.; Ji, W.-Y.; Wang, X.-Y.; Zhang, T.-F.; Shen, D.-Z. Supra-(carbon nanodots) with a Strong Visible to Near-infrared Absorption Band and Efficient Photothermal Conversion. Light Sci. Appl., 2016, 5, e (4) Sun, S.; Zhang, L.; Jiang, K.; Wu, A.; Lin, H. Toward High-Efficient Red Emissive Carbon Dots: Facile Preparation, Unique Properties, and Applications as Multifunctional Theranostic Agents. Chem. Mater., 2016, 28, S-14