View Article Online View Journal Lab on a Chip Devices and applications at the micro- and nanoscale Accepted Manuscript This article can be cited before page numbers have been issued, to do this please use: S. Hu, B. Zhang, S. Zeng, L. Liu, K. Yong, H. Ma and Y. Tang, Lab Chip, 2020, DOI: 10.1039/D0LC00202J. Volume 17 Number 1 This is an Accepted Manuscript, which has been through the 7 January 2017 Pages 1-200 Royal Society of Chemistry peer review process and has been Lab on a Chip accepted for publication. Devices and applications at the micro- and nanoscale Accepted Manuscripts are published online shortly after acceptance, rsc.li/loc before technical editing, formatting and proof reading. Using this free service, authors can make their results available to the community, in citable form, before we publish the edited article. We will replace this Accepted Manuscript with the edited and formatted Advance Article as soon as it is available. 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Nelson et al. shall the Royal Society of Chemistry be held responsible for any errors Charactization of size-dependent mechanical properties of tip-growing cells using a lab-on-a-chip device or omissions in this Accepted Manuscript or any consequences arising from the use of any information it contains. rsc.li/loc Page 1 of 10 Please doLab not on adjust a Chip margins View Article Online DOI: 10.1039/D0LC00202J ARTICLE Microfluidic Chips Enabled One-step Synthetization of Biofunctionalized CuInS2/ZnS Quantum Dots a d e c b a a Received 00th January 20xx, Siyi Hu, Butian Zhang, Shuwen Zeng, Liwei Liu, Ken-Tye Yong,* Hanbin Ma,* Yuguo Tang Accepted 00th January 20xx Biofunctionalized quantum dots (QDs) are effective targeted fluorescent labels for bioimaging. However, conventional DOI: 10.1039/x0xx00000x synthesis of biofunctionalized I-III-VI core-shell CuInS2/ZnS QDs requires complex bench-top operations, results in limited product performance and variety, and is not amenable to a ‘one-step’ approach. In this work, we have successfully demonstrated a fully automated method for preparing denatured bovine serum albumin (dBSA)-CuInS2/ZnS QDs by introducing microfluidic chips (MF) to synthesize biofunctionalized QDs, hence establishing a ‘one-step’ procedure. We have also studied and optimized the reaction synthesis parameters. The emission wavelength of dBSA-CuInS2/ZnS QDs is located in the near-infrared range and can be tuned from 650 to 750 nm by simply varying the reaction parameters. In addition, the ‘one-step’-synthesized dBSA-CuInS2/ZnS QDs have a long average fluorescence lifetime of 153.76 ns at a small particle size of 5±2 nm. To demonstrate the applicability of the ‘one-step’-synthesized dBSA-CuInS2/ZnS QDs in bioimaging studies, we modified the QDs with folic acid and hyaluronic acid, and then performed target bioimaging and cytotoxicity tests on Manuscript macrophages, liver cancer cells and pancreatic cancer cells. The cell images show that the red emission signals originate from the QDs, which indicates that the dBSA-CuInS2/ZnS QDs prepared by the MF approach are suitable optical contrast agents for target bioimaging. This ‘one-step’ MF-based QD synthesis approach could serve as a rapid, cost-effective, and small-scale nanocrystal production platform for complex QD formulations for a wide range of bioapplications. According to related reports, CuInS2 QDs are usually prepared Introduction in the oil phase, and studies of the aqueous phase method are relatively rare. The main barriers to the synthesis of aqueous- Quantum Dots (QDs) have achieved widespread use in phase CuInS QDs are as follows:1) The reaction temperature biomedical applications owing to the rapid development of 2 needs to be very precise; 2) The reaction time needs to be more their synthesis and biofunctionalization methods. In the past Accepted than 4 hours; 3) Cuprous ions are easily oxidized and need to be decade, cadmium-free I-III-VI QDs have been used in bio- handled carefully during the reaction4. However, with the application studies due to their low biotoxicity and 1 development of technology, some of the problems environmentally friendly natures . I-III-VI QDs, such as CuInS2 encountered in the synthesis of QDs can be solved by a new and AgInS2, which are cadmium-free QDs. In particular, CuInS2 method, such as microfluidics technology. QDs not only have low biotoxicity but also possess additional Chip Microfluidics (MF) has become a powerful tool for QD synthesis Published on 13 July 2020. Downloaded by University of Glasgow Library 7/13/2020 9:16:54 AM. chemical and physical properties such as a long and has several advantages over the bench-top(BT) method5, a photoluminescence (PL) lifetime, a large Stokes shift, a high such as minimal use of chemicals, reduced the raw materials, extinction coefficient, and adjustable PL potential in the visible- decreased reaction time, the possibility of carrying out several near-infrared region1-3. reactions at once, precisely controlled reaction conditions, on rapid heat transfer due to the large surface-to-volume ratios of the MF channels, and high integration6, 7. The first nanoparticle synthesis by MF chips was reported by Prof. Andrew deMello’s a. CAS Key Laboratory of Bio-medical Diagnostics, Suzhou Institute of Biomedical 8 group in 2002 ; they applied continuous flow-based MF chips to Lab Engineering and Technology, Chinese Academy of Sciences, No.88 Keling Road, Suzhou, Jiangsu, 215163, P.R. China. successfully synthesize CD’s nanoparticles. Since then, many b. School of Electrical and Electronic Engineering, Nanyang Technological University, kinds of metallic9, 10, metal oxide 11, magnetic12 and Quantum Singapore 639798, Singapore. 13-17 c. Key Laboratory of Optoelectronic Devices and Systems of Guangdong Province, dots nanoparticles have been successfully prepared by MF College of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, chips. China. Among the abovementioned materials, colloidal QDs have d. MOE Key Laboratory of Fundamental Physical Quantities Measurement, PGMF and School of Physics, Huazhong University of Science and Technology, Wuhan attracted much attention from researchers in the field of MF 430074, P. R. China. due to their unique physicochemical properties, and these QDs e. XLIM Research Institute, UMR 7252 CNRS/University of Limoges, Limoges, 87060, 18 France have many applications in the biomedical field . For the bio- * Corresponding author: [email protected] ; [email protected] . application of QDs, researchers have always modified the QDs Electronic Supplementary Information (ESI) available: [details of any supplementary 19 information available should be included here]. See DOI: 10.1039/x0xx00000x with biofunctional molecules to make them biocompatible ; Please do not adjust margins Please doLab not on adjust a Chip margins Page 2 of 10 ARTICLE Journal Name the whole process in the conventional BT method is very shape, wave shape and serpentine shape microchannel.View Article Online We complicated20. However, very little success has been realized by applied serpentine shape to preheat theDOI: reaction 10.1039/D0LC00202J precursor applying the BT method to synthesize biofunctionalized QDs in solution and to react the growth of QDs after nucleation. The Y- a single step21. Thus, MF chips with the advantage of high shape microchannels are used for mixing of precursor solution integrability can be modified with different functional units to and nucleation of QDs. And the wave shape microchannel is simultaneously synthesize and biofunctionalized nanomaterials mainly used to rapidly flow the solution of QDs after nucleation, 22 in a one-step experiment . through this channel to achieve the stirring function, so that the In this work, we report the use of a MF chip for the one-step QDs after nucleation can be dispersed in the reaction system to synthesis of biofunctionalized core/shell heavy metal-free achieve well dispersion of the final product. denatured bovine serum albumin (dBSA)-CuInS2/ZnS QDs. We have studied and optimized the reaction synthesis parameters. The emission wavelength of dBSA-CuInS2/ZnS QDs is located in the near-infrared range and can be tuned from 650 to 750 nm by simply varying the reaction parameters. The prepared QDs were then characterized by TEM, lifetime decay, and agarose gel electrophoresis. Because of the excellent liquid handling capabilities of the MF approach, the prepared QDs exhibit a high photostability and colloidal stability. To demonstrate the Figure 2. (a) the simulation model and the simulation result of applicability of the ‘one-step’-synthesized dBSA-CuInS2/ZnS QDs in bioimaging studies, we modified the QDs with folic acid the reaction temperature of 160°C and the flow rate of 0.2 (FA) and hyaluronic acid (HA) and then performed target ml/min, (b)The simulation study of the concentration bioimaging and cytotoxicity tests on macrophages, liver cancer distribution of the QDs synthesized by the microfluidic chips cells and pancreatic cancer cells. with different reaction temperature (100°C, 120°C, 140°C, 160°C and 180°C) and flow rate (0.1, 0.2, 0.3, 0.4 and 0.5 Manuscript ml/min). Results and discussion In this work, we first did the simulation study to investigate the influence of the flow rate and reaction temperature on the growth rate of QDs in the microfluidics chips. By using the Reaction Engineering (re), Chemistry(chem), transport of diluted species (tds), and laminar flow (spf) models in Comsol Multiphysics 5.4, the relationship between the yield of QDs and reaction condition (i.e. the flow rate and reaction temperature in the microfluidics chip) can be theoretically predicted.