Polymer Microfibers Incorporated with Silver Nanoparticles: a New Platform for Optical Sensing
- 198 Downloads
The enhanced sensitivity of up-conversion luminescence is imperative for the application of up-conversion nanoparticles (UCNPs). In this study, microfibers were fabricated after co-doping UCNPs with polymethylmethacrylate (PMMA) and silver (Ag) solutions. Transmission losses and sensitivities of UCNPs (tetrogonal-LiYF4:Yb3+/Er3+) in the presence and absence of Ag were investigated. Sensitivity of up-conversion luminescence with Ag (LiYF4:Yb3+/Er3+/Ag) is 0.0095 K−1 and reduced to (LiYF4:Yb3+/Er3+) 0.0065 K−1 without Ag at 303 K under laser source (980 nm). The UCNP microfibers with Ag showed lower transmission losses and higher sensitivity than without Ag and could serve as promising candidate for optical applications. This is the first observation of Ag-doped microfiber via facile method.
KeywordsMicrofibers Up-conversion luminescence Er3+ Ag Transmission losses Sensitivity
Joint committee on powder diffraction standards
Up-conversion nanoparticles microfibers
Trivalent lanthanide ions
Rare earth ions
Transmission electron microscope
Scanning electron microscope
X-ray photoelectron spectroscopy
Fourier transform infrared rays
Thermal gravimetric analysis
Fluorescence intensity ratio
Up-conversion nanoparticles (UCNPs) after co-doping with lanthanides ions have drawn much attention due to application in imaging, laser materials, display technologies, and solar cells [1, 2, 3]. The low fluorescence emission efficiency of UCNPs can be caused by the small absorption coefficients of lanthanide ions. The nanoscale dispersion of metal nanoparticles in polymeric and inorganic substrates has triggered a great interest in novel physical, chemical, and biologic properties of the nanocomposite materials . For potential applications of the further miniaturization of electronic components, optical detectors, chemical and biochemical sensors, and devices are exciting possibilities with metal nanoparticles. Additionally, the semiconductors have been used as sensitizers for widening absorption range, such as CdSe, CdS, PbS, WO3, and Cu2O [5, 6]. Among these semiconductors, Cu2O is an interesting candidate due to its narrow band gap of ~ 2.1 eV, non-toxicity, low cost and abundance but heterostructure of Cu2O/ZnO is a promising material structure. It leads to a functional intergration, novel interface effect's properties of Cu2O and ZnO material. Heterostructure Cu2O/ZnO is a promising material structure which leads to a functional integration of the properties of Cu2O and ZnO also to novel interface effects and phenomena . On the other hand, UCNPs depicts superior properties relative to semiconductor quantum dots for instance the absence of autofluorescence tissue penetrability near-infrared laser excitation, non-blinking, and high chemical stability . The synthesis of lanthanide-doped materials with spherical nanoparticles and nanorods has been studied by many research groups . The issue of UCNPs oxidation occurs at high temperature significantly which reduced their applications. To avoid oxidation, core/shell structure overcomes oxidation whereas SiO2 shell grows around nanocrystals. Nanocrystal integration on chip as microstructure light detector is difficult. Therefore, microtubes, quantum dot-doped nanofibers, and dye-doped polymer nanowires have been employed in microstructural optoelectronics technology after successful investigation . Correspondingly, nanowires, microtubes, and nanofibers have been fabricated and utilized to discuss the thermal sensing behavior by different research groups [11, 12].
However, metal nanoparticles (MNPs) have been considered to enhance UCNPs efficiency. Different strategies including chemical modification, crystal structure, and local field adjustment of metal have been proposed to improve the efficiency and sensitivity . Investigations on rare earth ion-doped luminescence materials for luminescence enhancement of metal nanostructure such as Er3+/Yb3+ co-doped bismuth-germinate glasses containing Ag nanoparticles and Er3+/Yb3+ co-doped β-NaLuF4 nanocrystals which are spin-coated over gold NPs have been reported with inconsistent results and high sensitivity . Moreover, aggregation-induced emission (AIE) is a distinctive fluorescence phenomenon which suggested that few dyes can emit stronger fluorescence in their solid state than in dispersion solution [15, 16, 17]. Different mechanism including J-aggregate formation, conformational planarization, and twisted intramolecular charge transfer for the AIE phenomenon has been previously proposed by researchers [18, 19, 20, 21, 22]. Besides, materials with AIE characteristics have attracted more research attention for potential application in various field organic light-emitting diode, chemosensing, and bioimaging [23, 24, 25, 26, 27]. Especially, the preparation of AIE-active fluorescent organic nanoparticles has attracted attention recently. These materials containing AIE dyes could emit strong luminescence in physiological solution which effectively conquers the aggregation-caused quenching effect of fluorescent organic nanoparticles based on typical organic dyes [28, 29]. Although many strategies for the preparation of AIE-active fluorescent organic nanoparticles have been developed, the preparation of AIE-active through facile and effective multicomponent reaction (MCR) has received rarely attention due to mismatch with experimental data [30, 31, 32, 33, 34]. So, the unique AIE properties of dyes showed very promising for the fabrication of ultra-bright luminescent polymeric nanoparticles [35, 36].
In maximum experimental study, powder samples were used to perform the spectral measurements that increased the concerns regarding the influence of aggregation inter-reflection. Therefore, it is necessary to establish a facile and simple strategy to overcome the abovementioned drawbacks. Thus, Ag nanoparticles after co-doping with UCNPs and PMMA solution were used in microfibers to enhance the luminescence. However, no results have been described focusing on Ag co-doped UCNPs to microfibers (UCNPs-MF).
LiYF4:Yb3+/Er3+ were synthesized using thermal decomposition method and co-doped with Ag nanoparticles (NPs), and PMMA solution was exploited to fabricate microfibers. Herein, we present a facile method to prepare microfibers from UCNPs/PMMA with and without Ag solutions. Especially, the photoluminescence properties of Ag and absence of Ag co-doped microfibers are studied at various excitation point of microfibers. Moreover, UC luminescence characteristics of a microfiber is investigated by exciting 980 nm diode laser source at different temperature for the purpose of temperature sensing. The dependence of the integrated FIR on temperature is obtained and the experimental data can be fitted well with an exponential function. Thus, a single microfiber having transitions 2H11/2→4I15/2 and 4S3/2→4I15/2 levels at 522 and 541 nm is used to calculate the thermal sensitivities. Moreover, a single microfiber having thermal sensitivities using transitions 2H11/2 → 4I15/2 and 4S3/2 → 4I15/2 levels at 522 and 541 nm will be evaluated.
Experimental and Method Section
The silver (Ag) powder, chloroform, cyclohexane, NaOH, NH4F, and ethanol were purchased from Shanghai Chemical Company, China. These chemicals were of analytic grade and used without further purification.
Preparation of Tetrogonal-LiYF4: Yb3+/Er3+ Nanoparticles
UCNP (tetrogonal-LiYF4:Yb3+/Er3+) was prepared using thermal decomposition technique. The three-necked flasks of 100 mL were used which contain rare earth ions with LnCl3 (Ln=Lu, Yb, Er) having a molar ratio of 78:22:1, respectively. The solution includes 15 mL 1-octadecene (ODE) and 6 mL oleic acid (OA). The mixture was heated up to 150 °C to obtain a pellucid solution and cooled up to room temperature after eliminating oxygen and residual water. Four millimoles of NH4F and 2.5 mmol of NaOH were added slowly into a flask containing 10 mL solution of methanol. To confirm, fluoride was dissolved entirely by stirring process up to 30 min after that prepared solution was heated at 300 °C at a rate of 50 °C/min for 1 h under argon atmosphere. The precipitates were separated at the rate of 4000 rpm and cooled down to room temperature, washed with ethanol, and dried at 60 °C for 12 h.
Fabrication of Ag Co-doped Fibers
Results and Discussion
Structure and Transmission Properties
To better understand the formation mechanism of Ag-doped microfibers, the thermal gravimetric analysis (TGA, NETZSCH) was conducted under a dry airflow from 293–393 K temperature. It is observed in Fig. 5b that a microfiber shows roughly two degradation steps. The first weight loss below 333 K could be attributed to loss of absorbed moisture/with the evaporation of trapped solvent (H2O or CHCl3) which is independent of sample composition. In graph, second weight loss happens from 333 K to 393 K which clearly represents the polymeric degradation process. Hence, Ag co-doped microfibers are polymer-based fibers which cannot stand with the temperature above 332 K .
Energy Levels and Thermal Effects
The sensitivity values of optical temperature sensors in different host materials
Intensity-dependent temperature sensitivity (K-1)
2H11/2,4S3/2 → 4I15/2
2H11/2,4S3/2 → 4I15/2
2H11/2,4S3/2 → 4I15/2
4G11/2,2H9/2 → 4I15/2
2H11/2,4S3/2 → 4I15/2
2H11/2,4S3/2 → 4I15/2
2H11/2,4S3/2 → 4I15/2
This may be linked to the highest sensitivity among other host materials, as displayed in Table 1. Furthermore, we observed that sensitivity of LiYF4:Yb3+/Er3+/Ag at 303 K is also higher than LiYF4:Yb3+/Er3+ manifested to a highly efficient photon to plasmon conversion of Ag nanoparticles in microfibers. The Ag co-doped microfibers are intrinsically immune to photobleaching which provided high stability dopant for optical sensing. It suggests that Ag co-doped fibers due to significant sensing properties are suitable for temperature recognition. As a result, the utilization of Ag nanoparticles in a microfiber is beneficial to increase the luminescence and to tailor thermal sensing properties, suggesting a promising sensitive temperature sensor.
In summary, tetrogonal-LiYF4:Yb3+/Er3+ were prepared via thermal decomposition method and fibers were fabricated after co-doping PMMA solution with Ag and UCNPs. Successful Ag incorporation in UCNPs was supported through SEM, TEM, EDS, XPS, FTIR, and TGA analysis. The Ag co-doped polymer microfibers with a wave-guiding excitation approach and demonstrated potential use in thermal sensor were investigated. The intensity-dependent temperature sensitivity of Ag microfiber (0.0095 K°1) is higher than undoped Ag (0.0065 K°1) at 303 K, proposing Ag-doped microfibers are potential candidates for upgrading intensity-based temperature sensitivity at room temperature, which opens up new opportunities for developing compact photonic and plasmonic devices with low optical power. In the development of a newly employed method of microfibers with specified properties, significant improvements in up-conversion enhancement may be possible, leading to a more efficient up-converter, thereby enabling many of the technological applications of these materials.
We acknowledge the characterization contribution of Engr. Muhammad Zeeshan Farooq from the Department of Material Science and Engineering, Harbin Institute of Technology, China, and the hard work of each member in our group. The authors do not have any kind of funding for this study.
MKS and AR performed the whole experiments and wrote the manuscript. YZ provided the novel idea to carry out the experiment. AA participated in the analyzes of the results and discussion of this study. MI, KQ, MUK, and MJA revised the manuscript and corrected the English. All authors read and approved the final manuscript.
The authors declare that they have no competing interests.
- 1.Elizabeth D, Lambertus H, John R, Roger M (1996) A three-color, solid-state, three-dimensional display. Sci 276:1185–1189Google Scholar
- 5.Xinwei Z, Huiqing F, Yuming T, Mingang Z, Xiaoyan Y (2012) Chemical bath deposition of Cu2O quantum dots onto ZnO nanorod arrays for application in photovoltaic devices. RSC Adv 5(30):23401–23409Google Scholar
- 7.Xin W, Huiqing F, Pengrong R (2103) Self-assemble flower-like SnO2/Ag heterostructures: correlation among composition, structure and photocatalytic activity. Colloids Surf A 419:140–146Google Scholar
- 14.Jun D, Zhenglong Z, Hairong Z, Mentao S (2015) Recent progress on plasmon-enhanced fluorescence. Nanophotonics 4:472–490Google Scholar
- 15.Jianzhao L, Jacky W-Y-L, Ben Z-T (2009) Acetylenic polymers: syntheses, structures, and functions. Chem Rev 11:5799–5867Google Scholar
- 16.Qing W, Qiang H, Meiying L, Dazhuang X, Hongye H, Xiaoyong Z, Yen W (2017) Aggregation-induced emission active luminescent polymeric nanoparticles: non-covalent fabrication methodologies and biomedical applications. Appl Mater Today 9:145–160Google Scholar
- 18.Ruming J, Meiying L, Tingting C, Hongye H, Qiang H, J T YW, Qian-yong C, Xiaoyong Z, Yen W (2018) Facile construction and biological imaging of cross-linked fluorescent organic nanoparticles with aggregation-induced emission feature through a catalyst-free aside-alkyne click reaction. Dyes Pigm 148:52–60CrossRefGoogle Scholar
- 25.Long H, Saijiao Y, Junyu C, Jianwen T, Qiang H, Hongye H, Yuan QW, Feng JD, Xiao YZ, Yen W (2019) A facile surface modification strategy for fabrication of fluorescent silica nanoparticles with the aggregation-induced emission dye through surface-initiated cationic ring opening polymerization. Mater Sci Eng C 94:270–278CrossRefGoogle Scholar
- 26.Ruming J, Meiying L, Hongye H, Liucheng M, Qiang H, Yuanqing W-Q-C, Jianwen T, Xiaoyong Z, Yen W (2018) Facile fabrication of organic dyed polymer nanoparticles with aggregation-induced emission using an ultrasound-assisted multicomponent reaction and their biological imaging. Chem Eng J 519:137–144Google Scholar
- 29.Hongye H, Meiying L, Qing W, Ruming J, Dazhuang X, Qiang H, Yuanqing W, Fengjie D, Xiaoyong Z, Yen W (2018) Facile fabrication of luminescent hyaluronic acid with aggregation-induced emission through formation of dynamic bonds and their theranostic applications. Mater Sci Eng C 91:201–207CrossRefGoogle Scholar
- 30.Ruming J, Han L, Meiying L, Jianwen T, Qiang H, Hongye H, Yuanqing W, Qianyong C, Xiaoyong Z, Yen W (2017) A facile one-pot mannich reaction for the construction of fluorescent polymeric nanoparticles with aggregation-induced emission feature and their biological imaging. Mater Sci Eng C 81:416–421CrossRefGoogle Scholar
- 31.Ruming J, Meiying L, Cong L, Qiang H, Hongye H, Qing W, Yuanqing W, Qianyong C, Xiao YH, Yen W (2017) Facile fabrication of luminescent polymeric nanoparticles containing dynamic linkages via a one-pot multicomponent reaction: synthesis, aggregation-induced emission and biological imaging. Mater Sci Eng C 80:708–714CrossRefGoogle Scholar
- 35.Yanzhu L, Liucheng M, Xinhua L, Meiying L, Dazhuang X, Ruming J, Fengjie D, Yongxiu L, Xiaoyong Z, Yen W (2017) A facile strategy for fabrication of aggregation-induced emission (AIE) active fluorescent polymeric nanoparticles (FPNs) via post modification of synthetic polymers and their cell imaging. Mater Sci Eng C 79:590–595CrossRefGoogle Scholar
- 38.Singho N-D, Lah N-A-C, Johan M-R, Ahmad R (2012) FTIR studies on silver-poly (methylmethacrylate) nanocomposites via in-situ polymerization technique. Int J Electrochem Sci 7:5596–5603Google Scholar
- 46.Muhammad K-S, Yundong Z, Muhammad U-K, Xiao S, Lu L, Hanyang L (2018) Upconversion thermometer through novel PMMA fiber containing nanocrystals. Opt Mater Express 8:332796–332804Google Scholar
Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.