多巴胺分子是人體中重要的神經傳遞物質，主要控制中樞神經系統，當濃度發生異常時會引起相關疾病(血清中正常濃度範圍約為0.01-1 μM)，例如帕金森氏症、亨丁頓舞蹈症和憂鬱症等。阿黴素是一種以蒽醌為基礎的抗癌藥物，被廣泛用於治療許多癌症，如乳癌，淋巴瘤，血液系統惡性腫瘤等。而當阿黴素在血液中濃度超過正常濃度指標時（0.078 μM）會引發一些副作用或是疾病，因此如何定量這兩種物質在人體中的濃度是現今科學家關注的重點。近年來研究中，矽量子點因受到量子侷限效應的影響具備獨特的光學特性，已被報導可應用於光電元件、感測材料、與生醫相關技術等領域。因此我們可以基於矽量子點的特性作為一種感測材料對其多巴胺分子與阿黴素進行濃度的感測，而在過去傳統合成矽量子點的方法多以水熱法、微波法、蝕刻法為主，其缺點在於操作繁瑣、高溫的製程環境以及冗長的反應時間等，皆違背現今研究致力於綠色製程的理念。因此，本研究主要目的為建構綠能合成以及感測技術，利用大氣常壓微電漿技術以低成本矽烷分子為前驅物合成出具有高經濟價值的矽量子點產物，並利用改變電漿物理參數（合成時間、合成電流）和化學參數（電解液種類、濃度）可成功合成出可調控波長的矽量子點，應用於光致發光感測儀對其多巴胺與阿黴素進行濃度的量測，此外，我們亦探討系統中可能的電漿合成機制與感測機制（螢光共振能量轉移、光誘導電子轉移）。

Recently silicon-based quantum dots (SiQDs), a semiconductor nanocrystals with quantum-confined induced properties, have been used in various field because of its unique electronic, optical, biomedical and mechanical properties. In particular, biosensing applications using SiQDs has received intensive attention owing to the good biocompatibility and low cytotoxicity. Dopamine (DA) is an indispensable catecholamine neurotransmitter which acts as an important role in our central nervous system to control the central nervous system-related diseases. Doxorubicin (DOX) is a kind of anthraquinone-based anticancer drug, which is widely used to treat a lot of cancers such as breast cancer, lymphoma, hematological malignancies, lung cancer and other tumor cells. However, as the concentration of the DA is abnormality in the human blood serum (0.01-1 μM) and the concentration of the DOX exceeds in biological fluid (0.078μM), which is possible to induce some side effects, thence, it is essential for the determination of the concentration.
For SiQD synthesis, the traditional approaches such as hydrothermal and microwave methods, which are time-consuming, high cost and complex reaction procedure. Here, we report a facile and rapid method, a microplasma synthesis of SiQDs for photoluminescence (PL) sensing of DA and DOX . Our study suggests that it is promising to synthesize the SiQDs using microplasmas at ambient conditions. In a typical synthesis, organosilane and sodium hydroxide were used as the precursor and electrolyte. Moreover, we adjust the physical parameters (time and current) and chemical parameters (electrolyte species and electrolyte concentration) to obtain tunable emission of SiQDs successfully. We also propose the possible sensing mechanism for the detection of DA and DOX. (Förster resonance energy transfer (FRET) and Photoinduced electron transfer (PET)). B-SiQDs as a luminescent probe for DA sensing demonstrates that a dual linear relationship of quenching intensity with DA concentration between 0.15-30 μM and 30-75 μM (LOD is 89.2 nM), and R-SiQDs as a luminescent probe for DOX sensing exhibits a linear relationship of quenching intensity with DOX concentration between 0.21-83.3 μM (LOD is 0.193 μM).

[1] T. Takagahara et al., Theory of the quantum confinement effect on excitons in quantum dots of indirect-gap materials, Physical Review B, 46(23), 15578 (1992).
[2] J. P. Wilcoxon et al., Optical and electronic properties of Si nanoclusters synthesized in inverse micelles, Physical Review B, 60(4), 2704 (1999).
[3] G. Sun et al., Intersubband approach to silicon based lasers—circumventing the indirect bandgap limitation, Advances in Optics and Photonics, 3(1), 53-87 (2011).
[4] A. C. Berends et al., Ultrathin one-and two-dimensional colloidal semiconductor nanocrystals: Pushing quantum confinement to the limit, The Journal of Physical Chemistry Letters, 8(17), 4077-4090 (2017).
[5] Y. He, et al., Silicon nanostructures for bioapplications, Nano Today, 5(4), 282-295 (2010).
[6] F. Peng et al., Silicon nanomaterials platform for bioimaging, biosensing, and cancer therapy, Accounts of Chemical Research, 47(2), 612-623 (2014).
[7] B. Delley et al., Quantum confinement in Si nanocrystals, Physical Review B, 47(3), 1397 (1993).
[8] N. M. Park et al., Quantum confinement in amorphous silicon quantum dots embedded in silicon nitride, Physical Review Letters, 86(7), 1355 (2001).
[9] S. Jagtap et al, A review on the progress of ZnSe as inorganic scintillator, Opto-Electronics Review, 27(1), 90-103 (2019).
[10] L. T. Canham et al., Silicon quantum wire array fabrication by electrochemical and chemical dissolution of wafers, Applied Physics Letters, 57(10), 1046-1048 (1990).
[11] J. L. Heinrich et al., Luminescent colloidal silicon suspensions from porous silicon, Science, 255(5040), 66-68 (1992).
[12] Z. Kang et al., Water‐soluble silicon quantum dots with wavelength‐tunable photoluminescence, Advanced Materials, 21(6), 661-664 (2009).
[13] P. G. Kale et al., Synthesis of Si nanoparticles from freestanding porous silicon (PS) film using ultrasonication, In 2010 35th IEEE Photovoltaic Specialists Conference, 003692-003697 (2010).
[14] S. H. Baek et al., Synthesis of fluorescent silicon quantum dots for ultra-rapid and selective sensing of Cr (VI) ion and biomonitoring of cancer cells, Materials Science and Engineering: C, 93, 429-436 (2018).
[15] T. Gong et al., Solid-state silicon nanoparticles with color-tunable photoluminescence and multifunctional applications, Journal of Materials Chemistry C, 7(20), 5962-5969 (2019).
[16] Z. Zhang et al., One-step hydrothermal synthesis of yellow and green emitting silicon quantum dots with synergistic effect, Nanomaterials, 9(3), 466 (2019).
[17] Y. He et al., One-pot microwave synthesis of water-dispersible, ultraphoto-and pH-stable, and highly fluorescent silicon quantum dots, Journal of the American Chemical Society, 133(36), 14192-14195 (2011).
[18] T. M. Atkins et al., Femtosecond ligand/core dynamics of microwave-assisted synthesized silicon quantum dots in aqueous solution, Journal of the American Chemical Society, 133(51), 20664-20667 (2011).
[19] K. H. Becker et al., Microplasmas and applications, Journal of Physics D: Applied Physics, 39(3), R55 (2006).
[20] D. Mariotti et al., Microplasmas for nanomaterials synthesis, Journal of Physics D: Applied Physics, 43(32), 323001 (2010).
[21] W. H. Chiang et al., Continuous-flow, atmospheric-pressure microplasmas: a versatile source for metal nanoparticle synthesis in the gas or liquid phase, Plasma Sources Science and Technology, 19(3), 034011 (2010).
[22] D. Mariotti et al., Low‐Temperature Atmospheric Pressure Plasma Processes for “Green” Third Generation Photovoltaics, Plasma Processes and Polymers, 13(1), 70-90 (2016).
[23] Chiang, W. H et al., Microplasmas for advanced materials and devices, Advanced Materials, 32(18), 1905508 (2020).
[24] D. Kurniawan et al., Microplasma-enabled colloidal nitrogen-doped graphene quantum dots for broad-range fluorescent pH sensors, Carbon, 167, 675-684 (2020).
[25] T. Nozaki et al., In-flight Microplasma Synthesis of Luminescent Silicon Quantum Dots in Macroscopic Quantities, ECS Transactions, 19(8), 3 (2009).
[26] J. J. Wu et al., Luminescent, water-soluble silicon quantum dots via micro-plasma surface treatment, Journal of Physics D: Applied Physics, 49(8), 08LT02 (2016).
[27] V. Švrček et al., Microplasma-induced surface engineering of silicon nanocrystals in colloidal dispersion, Applied Physics Letters, 97(16), 161502 (2010).
[28] S. Mitra et al., Microplasma‐Induce Liquid Chemistry for Stabilizing of Silicon Nanocrystals Optical Properties in Water, Plasma Processes and Polymers, 11(2), 158-163 (2014).
[29] S. Mitra et al., Improved optoelectronic properties of silicon nanocrystals/polymer nanocomposites by microplasma-induced liquid chemistry, The Journal of Physical Chemistry C, 117(44), 23198-23207 (2013).
[30] Cavalcante et al., Photoluminescence Properties of Nanocrystals (2012).
[31] Freeman, R., Nucleic acid/quantum dots (QDs) hybrid systems for optical and photoelectrochemical sensing, ACS Applied Materials & Interfaces, 5(8), 2815-2834 (2013).
[32] Zu et al., The quenching of the fluorescence of carbon dots: a review on mechanisms and applications, Microchimica Acta, 184(7), 1899-1914 (2017).
[33] Hussain et al., An introduction to fluorescence resonance energy transfer (FRET), arXiv preprint arXiv:0908.1815 (2009).
[34] T. Chen et al., Application of Förster Resonance Energy Transfer (FRET) technique to elucidate intracellular and In Vivo biofate of nanomedicines, Advanced Drug Delivery Reviews, 143, 177-205 (2019).
[35] S. Silvi et al., Luminescent sensors based on quantum dot–molecule conjugates, Chemical Society Reviews, 44(13), 4275-4289 (2015).
[36] C. M. Gonzalez et al., Detection of high-energy compounds using photoluminescent silicon nanocrystal paper based sensors, Nanoscale, 6(5), 2608-2612 (2014).
[37] S. Content et al., Detection of nitrobenzene, DNT, and TNT vapors by quenching of porous silicon photoluminescence, Chemistry-A European Journal, 6(12), 2205-2213 (2000).
[38] Y. B. Ruan et al., Highly sensitive naked-eye and fluorescence “turn-on” detection of Cu2+ using Fenton reaction assisted signal amplification, Chemical Communications, 46(48), 9220-9222 (2010).
[39] Y. Yi et al., Label-free Si quantum dots as photoluminescence probes for glucose detection, Chemical Communications, 49(6), 612-614 (2013).
[40] J. Zhao et al., Label-free silicon quantum dots as fluorescent probe for selective and sensitive detection of copper ions, Talanta, 125, 372-377 (2014).
[41] R. Ban et al., A highly sensitive fluorescence assay for 2, 4, 6-trinitrotoluene using amine-capped silicon quantum dots as a probe, Analytical Methods, 7(5), 1732-1737 (2015).
[42] D. L. Robinson et al., Monitoring rapid chemical communication in the brain, Chemical Reviews, 108(7), 2554-2584 (2008).
[43] S. E. Hyman et al., Addiction and the brain: the neurobiology of compulsion and its persistence, Nature Reviews Neuroscience, 2(10), 695-703 (2001).
[44] D. Wu et al., Sensitive determination of norepinephrine, epinephrine, dopamine and 5‐hydroxytryptamine by coupling HPLC with [Ag (HIO6)2]5- luminol chemiluminescence detection, Biomedical Chromatography, 30(9), 1458-1466 (2016).
[45] J. M. Zen et al., A selective voltammetric method for uric acid and dopamine detection using clay-modified electrodes, Analytical Chemistry, 69(24), 5087-5093 (1997).
[46] X. Zhang et al., Highly sensitive and selective detection of dopamine using one-pot synthesized highly photoluminescent silicon nanoparticles, Analytical Chemistry, 87(6), 3360-3365 (2015).
[47] Z. Liu et al., A dopamine-modulated nitrogen-doped graphene quantum dot fluorescence sensor for the detection of glutathione in biological samples, New Journal of Chemistry, 40(10), 8911-8917 (2016).
[48] J. Zhao et al., Graphene quantum dots as effective probes for label-free fluorescence detection of dopamine, Sensors and Actuators B: Chemical, 223, 246-251 (2016).
[49] X. Chen et al., Fluorescence detection of dopamine based on nitrogen-doped graphene quantum dots and visible paper-based test strips, Analytical Methods, 9(15), 2246-2251(2017).
[50] Y. Ma et al., Doping effect and fluorescence quenching mechanism of N-doped graphene quantum dots in the detection of dopamine, Talanta, 196, 563-571 (2019).
[51] R. Das et al., Highly sensitive and selective label-free detection of dopamine in human serum based on nitrogen-doped graphene quantum dots decorated on Au nanoparticles: mechanistic insights through microscopic and spectroscopic studies, Applied Surface Science, 490, 318-330 (2019).
[52] A. Kumar et al., Single-step synthesis of N-doped carbon dots and applied for dopamine sensing, in vitro multicolor cellular imaging as well as fluorescent ink, Journal of Photochemistry and Photobiology A: Chemistry, 406, 113019 (2021).
[53] N. Chavoshi et al., Fluorescent Carbon Dots Prepared from Hazelnut Kohl as an Affordable Probe for Determination of Dopamine, Journal of Fluorescence, 31(2), 455-463(2021).
[54] A. Xiangzhao et al., Nanosensor for dopamine and glutathione based on the quenching and recovery of the fluorescence of silica-coated quantum dots, Microchimica Acta, 180(3), 269-277(2013).
[55] Q. Mu et al., Adenosine capped QDs based fluorescent sensor for detection of dopamine with high selectivity and sensitivity, Analyst, 139(1), 93-98 (2014).
[56] G. J. Quigley et al., Molecular structure of an anticancer drug-DNA complex: daunomycin plus d (CpGpTpApCpG), Proceedings of the National Academy of Sciences, 77(12), 7204-7208 (1980).
[57] J. I. Jung et al., Thoracic manifestations of breast cancer and its therapy, Radiographics, 24(5), 1269-1285 (2004).
[58] S. R. Urva et al., Sensitive high performance liquid chromatographic assay for assessment of doxorubicin pharmacokinetics in mouse plasma and tissues, Journal of Chromatography B, 877(8-9), 837-841 (2009).
[59] I. Sardi et al., Detection of doxorubicin hydrochloride accumulation in the rat brain after morphine treatment by mass spectrometry, Cancer Chemotherapy and Pharmacology, 67(6), 1333-1340 (2011).
[60] Y. Guo et al., Electrochemical sensor for ultrasensitive determination of doxorubicin and methotrexate based on cyclodextrin‐graphene hybrid nanosheets, Electroanalysis, 23(10), 2400-2407 (2011).
[61] K. Y. Huang et al., Gold nanocluster-based fluorescence turn-off probe for sensing of doxorubicin by photoinduced electron transfer, Sensors and Actuators B: Chemical, 296, 126656 (2019).
[62] M. Yang et al., Polyethyleneimine-functionalized carbon dots as a fluorescent probe for doxorubicin hydrochloride by an inner filter effect, Optical Materials, 112, 110743 (2021).
[63] X. Gao et al., Detection of DNA via the fluorescence quenching of Mn-doped ZnSe D-dots/doxorubicin/DNA ternary complexes system, Journal of Fluorescence, 22(1), 103-109 (2012).
[64] X. Gao et al., CuInS2 quantum dots/poly (l-glutamic acid)–drug conjugates for drug delivery and cell imaging, Analyst, 139(4), 831-836 (2014).
[65] F. Chekin et al., Graphene-modified electrodes for sensing doxorubicin hydrochloride in human plasma, Analytical and Bioanalytical Chemistry, 411(8), 1509-1516 (2019).
[66] D. Li et al., A facile synthesis of hybrid silicon quantum dots and fluorescent detection of bovine hemoglobin, New Journal of Chemistry, 43(48), 19338-19343 (2019).
[67] W. Cheng et al., Calculations on the size effects of Raman intensities of silicon quantum dots, Physical Review B, 65(20), 205305 (2002).
[68] G. Faraci et al., Quantum size effects in Raman spectra of Si nanocrystals, Journal of Applied Physics, 109(7), 074311 (2011).
[69] Y. Zhang et al., Photoluminescence of silicon quantum dots in nanospheres, Nanoscale, 4(24), 7760-7765 (2012).
[70] A. A. Bagabas et al., A study of laser-induced blue emission with nanosecond decay of silicon nanoparticles synthesized by a chemical etching method, Nanotechnology, 20(35), 355703.
[71] J. H. Warner et al., Water‐soluble photoluminescent silicon quantum dots, Angewandte Chemie International Edition, 44(29), 4550-4554 (2005).
[72] J. Wu et al., One-step synthesis of fluorescent silicon quantum dots (Si-QDs) and their application for cell imaging, RSC Advances, 5(102), 83581-83587 (2015).
[73] L. Luo et al., Fluorescent silicon nanoparticles-based ratiometric fluorescence immunoassay for sensitive detection of ethyl carbamate in red wine, Sensors and Actuators B: Chemical, 255, 2742-2749 (2018).
[74] S. Soulé et al., Thermoresponsive gold nanoshell@ mesoporous silica nano-assemblies: an XPS/NMR survey, Physical Chemistry Chemical Physics, 17(43), 28719-28728 (2015).
[75] J. S. Yang et al., Microplasma-enhanced synthesis of colloidal graphene quantum dots at ambient conditions, Carbon, 153, 315-319 (2019).
[76] A. Thiha et al., Microplasma direct writing for site-selective surface functionalization of carbon microelectrodes, Microsystems & Nanoengineering, 5(1), 1-12 (2019).
[77] D. Kurniawan et al., Microplasma-enabled colloidal nitrogen-doped graphene quantum dots for broad-range fluorescent pH sensors, Carbon, 167, 675-684 (2020).
[78] F. Rezaei et al., Investigation of plasma‐induced chemistry in organic solutions for enhanced electrospun PLA nanofibers, Plasma Processes and Polymers, 15(6), 1700226 (2018).
[79] B. B. Sahu et al., Plasma engineering of silicon quantum dots and their properties through energy deposition and chemistry, Physical Chemistry Chemical Physics, 18(37), 25837-25851 (2016).
[80] H. K. Sadhanala et al., Boron-doped carbon nanoparticles: Size-independent color tunability from red to blue and bioimaging applications, Carbon, 96, 166-173 (2016).
[81] Y. Wei et al., Liquid-phase plasma synthesis of silicon quantum dots embedded in carbon matrix for lithium battery anodes, Materials Research Bulletin, 48(10), 4072-4077.
[82] G. Rajender et al., Formation mechanism of graphene quantum dots and their edge state conversion probed by photoluminescence and Raman spectroscopy, Journal of Materials Chemistry C, 4(46), 10852-10865 (2016).
[83] J. C. Vinci et al., Spectroscopic characteristics of carbon dots (C-dots) derived from carbon fibers and conversion to sulfur-bridged C-dots nanosheets, Applied Spectroscopy, 69(9), 1082-1090 (2015).
[84] J. Peng et al., Graphene quantum dots derived from carbon fibers, Nano Letters, 12(2), 844-849.
[85] J. Wu et al., Investigation of the microstructures of graphene quantum dots (GQDs) by surface-enhanced Raman spectroscopy, Nanomaterials, 8(10), 864 (2018).
[86] S. Sivasubramaniam et al., Performance enhancement in silicon solar cell by inverted nanopyramid texturing and silicon quantum dots coating, Journal of Renewable and Sustainable Energy, 6(1), 011204 (2014).
[87] T. S. Basu et al., Single-electron transport through stabilised silicon nanocrystals, Nanoscale, 10(29), 13949-13958 (2018).
[88] K. Chen et al., Experimental evidence of exciton capture by mid-gap defects in CVD grown monolayer MoSe 2, npj 2D Materials and Applications, 1(1), 1-8 (2017).
[89] S. Li et al., Self-trapped excitons in all-inorganic halide perovskites: fundamentals, status, and potential applications, The Journal of Physical Chemistry Letters, 10(8), 1999-2007 (2019).
[90] Y. Wang et al., Thickness-dependent full-color emission tunability in a flexible carbon dot ionogel, The Journal of Physical Chemistry Letters, 5(8), 1412-1420 (2014).
[91] Y. Zhou et al., A novel composite of graphene quantum dots and molecularly imprinted polymer for fluorescent detection of paranitrophenol, Biosensors and Bioelectronics, 52, 317-323 (2014).
[92] Nandiyanto et al., How to read and interpret FTIR spectroscope of organic material, Indonesian Journal of Science and Technology, 4(1), 97-118 (2019).
[93] X. Ji et al., On the pH-dependent quenching of quantum dot photoluminescence by redox active dopamine, Journal of the American Chemical Society, 134(13), 6006-6017 (2012).
[94] C. Zhao et al., Hydrothermal synthesis of nitrogen-doped carbon quantum dots as fluorescent probes for the detection of dopamine, Journal of fluorescence, 28(1), 269-276 (2018).
[95] L. Zhao et al., Doxorubicin induces cardiotoxicity through upregulation of death receptors mediated apoptosis in cardiomyocytes, Scientific Reports, 7(1), 1-11 (2017).
[96] S. Liu et al., Facile synthesis of Cu (II) impregnated biochar with enhanced adsorption activity for the removal of doxycycline hydrochloride from water, Science of the Total Environment, 592, 546-553 (2017).
[97] Z. Xu et al., Molecularly imprinted fluorescent probe based on FRET for selective and sensitive detection of doxorubicin, Materials Science and Engineering: B, 218, 31-39 (2017).
[98] M. Amelia et al., Structural and size effects on the spectroscopic and redox properties of CdSe nanocrystals in solution: the role of defect states, ChemPhysChem, 12(12), 2280-2288 (2011).
[99] M. Kiguchi et al., Compendium of Surface and Interface Analysis, Springer (2018).
[100] R. Ye et al., Bandgap engineering of coal-derived graphene quantum dots, ACS Applied Materials & Interfaces, 7(12), 7041-7048 (2015).
[101] J. Zhan et al., A solvent-engineered molecule fusion strategy for rational synthesis of carbon quantum dots with multicolor bandgap fluorescence, Carbon, 130, 153-163 (2018).