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An Ultra-Sensitive Plasmonic Nanosensor for Aldehydes Meng Li, Lei Shi, Tao Xie, Chao Jing, Guangli Xiu, and Yi-Tao Long ACS Sens., Just Accepted Manuscript • DOI: 10.1021/acssensors.6b00769 • Publication Date (Web): 16 Jan 2017 Downloaded from http://pubs.acs.org on January 17, 2017
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An Ultra-Sensitive Plasmonic Nanosensor for Aldehydes Meng Li *ab‡, Lei Shi c‡, Tao Xie a, Chao Jing ad, Guangli Xiub, Yi-Tao Long *a a.
Key laboratory for Advanced Materials, School of Chemistry & Molecular Engineering, East China University of Science and Technology, 130 Meilong Road, Shanghai, 200237, P. R. China.s b. State Environmental Protection Key Laboratory of Risk Assessment and Control on Chemical Processes, East China University of Science and Technology, Shanghai 200237, P.R. China c. Shanghai Qingpu Water Authority. 35 Xidayingangyi Road, Shanghai, 201799, P. R. China d. Physik-Department E20, Technische Universität München, James-Franck-Str.1 D-85748 Garching Supporting Information Placeholder ABSTRACT: Glucose is the most common but important aldehydes, and it is necessary to create biosensors with high
sensitivity and anti-interference to detect it. Under the existence of silver ions and aldehyde compounds, single gold nanoparticles and fresh formed silver atoms could respectively act as core and shell, which finally form a core-shell structure. By observing the reaction between glucose and Tollens' reagent, metallic silver was found to be reduced on the surface of gold nanoparticles and formed Au@Ag nanoparticles that leading to a direct wavelength shift. Based on this principle and combined with in situ plasmon resonance scattering spectra, plasmonic nanosensor was successfully applied in identifying aldehyde compounds with excellent sensitivity and specificity. This ultra-sensitive sensor was successfully further utilized to detect blood glucose in mice serum samples, exhibiting good anti-interference ability and great promising for future clinical application.
KEYWORDS glucose sensor, plasmonic, nanoparticles, ultra-sensitive, anti-interference
Since gold nanoparticles (GNPs) are extremely sensitive and extensive indicators, their applications include colorimetric, electro-optical conversion, chemical and biological sensing1, 2. Due to the electron oscillations induced by the incident light, GNPs display strong plasmon scattering light that could reflect a tiny fluctuation in the surroundings or composition of the particle itself3, 4. Their excellent optical property indicated that GNPs could be utilized as plasmonic sensors at single nanoparticle level with ultra-high sensitivity, also applied in catalysis and chemical reaction monitoring5, 6. To amplify the spectral response of GNPs, several strategies have been adopted and the simplest method was to change its morphology, such as forming satellite nanoparticles or bimetallic nanomaterial7, 8. Some colorimetric sensors based on GNPs were developed to detect glucose, and the most common one was the Au@Ag core-shell nanoparticles. With the existence of glucose and glucose oxidase (GOx), the reaction product H2O2 would etch silver shell and lead to a distinct color change of the solution9,10. But the preparation of Au@Ag nanoparticles seems complicated and too much reagent would introduce into the sensing system, which might cause interference. A reverse route to form Au@Ag, instead of dissolving silver shell, would be easy to operate and control.
Silver mirror reaction is a classic and essential method to distinguish between an aldehyde and a ketone. In the presence of an aldehyde or alpha-hydroxy ketone functional groups, silver ions contained in Tollens' reagent are reduced into metallic silver and formed a mirror on the clean glassware11. Single GNPs were introduced as a medium during the reaction process, when diamminesilver(I) complex ([Ag(NH3)2]+), as the main component that Tollens’ reagent contains, reacted with glucose and then generate Ag0 around the GNPs to form Au@Ag nanoparticles. This concept was previously applied to detect glucose via the color change of solution that could be distinguished directly by the naked eyes12, 13. Instead of detecting UV-Vis spectra of a throng of particles, we in situ monitored the scattering spectra of a single gold nanoparticle. Therefore, the detection limit to glucose could reach to the single-particle level and thus would consume less initial sample amount. Moreover, we could analyze the dark-field image via an MATLAB-based program, the spectra peaks of a batch of nanoparticles could be obtained very quick and applied for further statistics. Therefore, the scattering spectrum of a bare GNP was then tuned by the formation of Au@Ag nanoparticles. In this paper, the plasmon resonance Rayleigh scattering spectra and dark-field microscopy (DFM) were utilized 1 ACS Paragon Plus Environment
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to investigate the growth procedure of single Au@Ag nanoparticle14. While the reaction was processing, the scattering spectra peak of GNPs gradual blue shifted and the spectral shift was related to the concentration of glucose. Through in situ monitoring the scattering spectra of this GNPs-based plasmonic nanosensor, the aldehydes could be quantified depending on the scattering wavelength shifts. Herein, we take the most common but important aldehydes, glucose, as an example to confirm the feasibility of this optical nanosensor. MATERIALS AND METHODS Materials. All reagents were of analytical grade. Hydrogen tetrachloroaurate trihydrate (HAuCl4·3H2O, >99.0%), ammonium hydroxide (NH3·H2O), ascorbic acid and bovine serum albumin (BSA) were acquired from Sigma-Aldrich Co. Ltd (St Louis, MO, United States). Ethanol, acetone, sodium citrate, hydroxylamine hydrochloride, potassium hydroxide (KOH) were purchased from J&K Scientific Ltd. (Shanghai, China). Ultrapure water with a resistivity of 18.2 MΩ cm was produced using a Milli-Q apparatus (Millipore Co., Milford, MA, United States) and used in the preparation of all the solutions. Indium tin oxide (ITO)-coated glass (sheet resistances 20-30 Ω sq-1) was purchased from Shenzhen Laibao Hi-tech Co. Ltd. (Shenzhen, China). Preparation of Tollens’ reagent and citrate gold nanoparticles. Diluted potassium hydroxide (0.8 mol/L) was mixed with 6.0 mL AgNO3 solution (0.1 mol/L) until forming the silver oxide, which precipitated from the solution as brown solid. Then ammonia (15.0 mol/L) was added dropwise to the solution until it becomes clear. The resulting solution contains the [Ag(NH3)2]+ complexes which are the main component. The Tollens’ reagent was freshly prepared just before using and stored in the dark. Gold nanoparticles with average diameters of 60 nm were prepared by the citrate-mediated reduction of HAuCl4. 50 mL of 0.01 wt% HAuCl4 was heated to reflux with vigorous stirring and then 565 µL sodium citrate (1%) was added quickly to the solution. The mixed solution was heating for 15 minutes continuously and stopped, but kept stirring for another 15 minutes. The resulting solution of colloidal particles was filtered and characterized by UV-Vis spectroscopy. Preparation of GNP-modified Slides and Serum Samples. ITO slides were rinsing in an ultrasonic bath with soapy water, acetone, ethanol, distilled water, respectively. Each step lasted for 60 minutes. After ultrasonication, the slides were washed with ultrapure water and dried under a nitrogen stream before immobilization of GNPs. These unstained slides were immersed into diluted aqueous GNP solutions (about 0.02 nmol/L) for 5 minutes. After that, the GNP-modified slides were carefully rinsing with ultrapure water and then placed on the dark-field microscopy platform to record its scatte-
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ring spectra. The total volume of the solution was about 250 µL. In order to prove its practicality, this sensing system was utilized to detect average blood glucose level of mice. Blood samples (100 µL) were collected from the orbital venous plexus of mice under ether anesthesia and then kept on ice for 2 h, centrifuged at 16,000 ×g for 1 min at 4°C, and its supernatant was immediately separated from the pellet. In order to obtain values within the range of the standard curve we previously obtained, the serum samples would be diluted 100,000 fold using a standard protocol for further analysis. During the experiment processing, 50 µL diluted serum sample and freshly prepared Tollens’ reagent were added onto the GNP-modified ITO slides and the final volume of the solution is 250 µL. Dark-field images and scattering spectra of GNPs were both recorded during the sensing process for further statistical analysis. Apparatus. The UV-Vis spectra were recorded using a USB 2000+ spectrometer with an Ocean Optics DTmini-2 halogen resource (Ocean Optics, USA). The dark-field spectrum measurements were carried out on an inverted microscope (eclipse Ti-U, Nikon, Japan) equipped with a dark field condenser (0.8 < NA < 0.95) and a 40× objective lens (NA = 0.8). A 100 W halogen lamp provides a white light source for exciting the GNPs and generating plasmon resonance scattering light. The dark-field color images were captured by using a truecolor digital camera (Nikon DS-fi), The scattering light of the gold nanoparticle was split by a monochromator (Acton SP2300i) equipped with a grating (grating density: 300 L/mm; blazed wavelength: 500 nm) and recorded by a spectrometer CCD (CASCADE 512B, Roper Scientific, PI) to obtain the scattering spectra. The true-color scattering images of gold nanoparticles were taken using a 40× objective lens (NA = 0.8). GNP fictionalized slides were immobilized on a platform. At first, scattering light of single nanoparticle was captured in 200 µL Tollen’s reagent (30.0 µM) as the initial spectral wavelength. Then, the glucose solution was added to the slide. The time-dependent scattering spectra of the single nanoparticle was obtained with the processing of silver mirror reaction. The scattering spectra from the individual nanoparticle was corrected by subtracting the background spectra taken from the adjacent regions without the GNPs and dividing with the calibrated response curve of the entire optical system. The spectra was integrated at 5 seconds.
RESULTS AND DISCUSSION Analytical Performance of the Plasmonic Nanosensors. GNPs were sparsely functionalized onto an ITO glass slide and treated with a freshly prepared Tollens' reagent and glucose solution. Their scattering spectra were recorded every 10 minutes by dark-field spectroscopy. To control the consistency of the experiment and
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obtain sensitive signals, the size of GNPs was screened at first. Figure S3 was the plasmon band shift values (∆λmax) of GNPs in different sizes. The results revealed that the GNPs with diameters of 60 nm shifted to the largest extent.
Figure 1. (A) Representative time-dependent single GNP scattering spectra upon introducing 24.0 µM Tollens’ reagent and 90.0 nM glucose, showing that the scattering spectra peaks are blue-shifting (0 ~ 60 min). The insets are the color image of a typical GNP before and after silver mirror reaction, demonstrating its color transition from yellowgreen to cyan. (B) Calibration plot corresponded to the Δλmax shifts of the scattering spectra at different concentrations of glucose. The error bars represent the standard deviation of three measurements.
During the measurement, Tollens’ reagent and glucose were dropped onto the ITO slide in order. The concentration of Tollens' reagent and glucose was 24.0 µmol/L and 90.0 nmol/L, respectively. When the reaction was taking place spontaneously at room temperature, silver ions were reduced as silver atoms and nucleated on the surface of GNPs, so that the color of nanoparticles changed from orange to cyan in dark-field microscopy (insets of Figure 1A). By comparing the intensity normalized scattering spectra, we noticed that the scattering spectra were blue-shifted ca. 22.0 nm from 560 to 538 nm after 60 minutes (Figure 1A). The corresponding time-dependent peak shifts were curved as Figure S4. It is noticeable that ∆λmax increased rapidly with the reaction undergoing and reaching a plateau about 40 minutes later, indicating that the reaction has come to a saturation state. The control experiment was conducted under the same conditions but using deionized water instead of glucose solution. By contrast, individual GNPs were observed to be very stable over the same period, meaning that the existence of glucose was essential for processing the reaction. The relationship between the concentration of glucose and the blueshifts was proved as the calibration plot in Figure 1B. For the glucose ranging from 0 to 160 nM, the ∆λmax value increased with glucose concentration added into the sensing system. The linear regression was fitted as [glucose] = (plasmon band shifts)*5.08 - 21.7 and the detection limit was calculated to be 0.949 nmol/L based on a 3σb/slope, where σb is the standard deviation of three blank samples following the IUPAC criterion. This detection limit was compared favourably with previous reports applying other colorimetric methods15, 16.
To further investigate the silver mirror reaction taking place on GNPs and in situ trace the nanoparticles forming, field-emission scanning electron microscope (FESEM) was utilized to characterize the morphology change. Two particular GNPs were selected as examples. The dark-field images, scattering spectra and corresponding FE-SEM images of these two nanoparticles were recorded before and after the epitaxial growth in Figure S5. The scattering spectra exhibited apparent blueshift, and the color of both two nanoparticles changed from yellow-green to cyan. Moreover, FE-SEM images confirmed the formation of Au@Ag nanoparticles. Evidence of Forming Au@Ag Nanoparticles. The electrochemical stripping analysis was carried out to confirm the existence of silver that has been coated on GNPs. An ITO electrode, which was modified with GNPs first and reacted under Tollens’ reagent and glucose for 60 minutes, was prepared for further potentiometric stripping analysis. The potential for stripping coated silver was set at 0.30 V (vs. Pt wire). About 100 seconds later, the color of these nanoparticles in dark-field microscopy images (Figure 2A and 2B) changed back to yellow-green with brightness decaying, indicating that the size of the nanoparticles became smaller than the ones before stripping. The statistical results were further presented as insets of Figure 2A and 2B via an RGB-ToWavelength MATLAB program17 and the samples used for statistics are more than 1,000 nanoparticles. Comparing the scattering wavelength distribution of the same nanoparticles before and after electrochemical stripping, it is apparent that the scattering peaks of Au@Ag nanoparticles formed after Tollen’s reaction are mostly at 557 nm, while red-shifted to 562 nm after stripping. The results of the stripping experiment demonstrated that silver was dissolved under the potential and Au@Ag nanoparticles mostly changed back to the initial gold nanoparticles. Moreover, real time scattering spectra of a particular nanoparticle was collected, the comparison of these spectra before and after stripping showed the λmax shifted back nearly to the fundamental wavelength of GNPs (Figure 2C). It is clear that there was silver existed and it is the formation of Au@Ag nanoparticles that generated the blueshift after adding glucose18,19. Moreover, it exhibited promising repeatability for the plasmonic nanosensor.
Figure 2. Dark-field images of (A) formed Au@Ag nanoparticles and (B) nanoparticles after electrochemical strip-
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ping. Insets are histograms of nanoparticles diameter and lines represent the density. (C) Scattering spectra of single Au@Ag nanoparticle I) before and II) after stripping.
However, when glucose was in extremely high concentration, the nucleation of free-standing silver nanoparticles would also emerge, owing to the direct nucleation process of silver nanocrystals in solution20. Figure S6 exhibited the DFM images before and after adding 10.0 µM glucose into the sensing system. More and more bright spots, which were considered as the dissociative silver nanoparticles, gradually appeared in the visual view. At the same time, the color of GNPs modified on the ITO glass was also found to be changed to cyan at the same time. This phenomenon might be directed by the abundance of glucose that favors nucleation, which generates silver nanocrystals in solution instead of epitaxial growth on the surface of GNPs. It is concluded that low concentration reductant could guarantee a slow rate of crystallization, so that these freshly emerged silver nanoparticles would nucleate on the surface of GNPs and cause blue-shifts of its scattering spectra, which was because of the hybridization of the dielectric constants of silver and gold. But an abundance of glucose would produce free silver nanocrystals and influence the detection. Serum Samples Analysis. This GNP-based nanosensor could be applied to detect blood glucose level in real samples. Considering other reductants contained in blood might affect sensing glucose, the influence of ascorbic acid, which is the most common reductant in blood, albumins and sodium chloride were investigated. The mean value of average blood glucose level in healthy people is about 5.5 mmol/L, while ascorbic acid is between 34 ~ 85 µmol/L (almost 1% of glucose), albumin concentrations in serum is approximately 0.52 mmol/L and sodium is nearly 140 mmol/L21-24. Therefore, interference of 1.0 nmol/L ascorbic acid, 10.0 nmol/L BSA and 1.0 µmol/L NaCl were considered and there were no apparent scattering wavelength shifts observed under the same experimental conditions (representative spectra were imaged in Figure S7). Moreover, the wavelengths of about 1,000 nanoparticles were gathered via the RGB-To-Wavelength MATLAB program, and the change before and after these reagents was analyzed using the statistical method (Table S1) that showed p-value < 0.05. The results exhibited that these representative reagents in blood serum would not affect the detecting of glucose, and also indicated that this plasmonic nanosensor introduced here could be applied for further analysis.
Figure 3. (A) Representative time-dependent single GNP scattering spectra upon introducing 24.0 µmol/L Tollens’ reagent into mice serum (diluted by 100,000 fold). The insets display color change of one single GNP in dark-field microscopy and the calibration plot corresponded to the Δλmax shifts of the scattering spectra at different concentrations of glucose. The error bars represent the standard deviation of three measurements. (B) Corresponding statistical scattering wavelength distribution of nanoparticles modified on ITO slide.
Before detection, blood serum sample of mice was diluted 100,000 fold according to a standard protocol and the volume used for sensing is about 50 µL. After GNPs were modified onto ITO electrode and their scattering spectra were monitored during the entire period of sensing. After adding Tollens' reagent and a serum sample for about 40 minutes, the final shift is about 7 nm and most nanoparticles were changed to cyan (Figure S8), which is the same with the previous experiments. A representing scattering spectra shift was recorded as Figure 3A and the corresponding statistical results of all nanoparticles were analyzed in Figure 3B, the total number of statistics is around 1,000 nanoparticles. The real sample analysis results proved that glucose in mice serum sample reacted with Tollens' reagent and formed Au@Ag nanoparticles. According to the linear fitting, the concentration of glucose in this serum sample was calculated as 13.8 nmol/L while the standard concentration is 14.0 nmol/L, demonstrating that this nanosensor is suitable for real sample detection with high accuracy and sensitivity.
CONCLUSION In conclusion, we used gold nanoparticle as an ultrasensitive plasmonic nanosensor to detect glucose. Tollens’ reagent was introduced into this sensing system on the basis of silver mirror reaction, and the formation of Au@Ag nanoparticles was proved and characterized. Moreover, scattering spectra shifts are related to the glucose concentration. The detection limit of this GNPbased nanosensor was calculated as low as 0.949 nmol/L and it was also successfully applied to sensing glucose in mice serum samples with excellent anti-interference ability and sensitivity. This plasmonic sensor demonstrated promising applications in detecting other aldehydes in the clinical analysis in the near future.
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ASSOCIATED CONTENT Supporting Information. Characterization of gold nanoparticles, optimization and additional data. The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acssensors.xxxx.
AUTHOR INFORMATION Corresponding Author
*E-mail:
[email protected] *E-mail:
[email protected] Tel: +86-21-65252339, Fax: 86-21-64252339. Author Contributions
‡M. Li and L. Shi contributed equally to this work. Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENT This research was supported by the Science Fund for Creative Research Groups (21421004), the National Natural Science Foundation of China (21327807), the Program of Shanghai Subject Chief Scientist (15XD1501200), the Programme of Introducing Talents of Discipline to Universities (B16017), and the State Key Laboratory of Analytical Chemistry for Life Science Open Foundation (SKLACLS1512).
REFERENCES (1) Elghanian, R.; Storhoff, J. J.; Mucic, R. C.; Letsinger, R. L.; Mirkin, C. A. Selective Colorimetric Detection of Polynucleotides Based on the Distance-Dependent Optical Properties of Gold Nanoparticles. Science 1997, 277 (5329), 1078-1081. (2) Liu, J.; Lu, Y. A Colorimetric Lead Biosensor Using DNAzyme-Directed Assembly of Gold Nanoparticles. J. Am. Chem. Soc. 2003, 125 (22), 6642-6643. (3) Li, K.; Qin, W.; Li, F.; Zhao, X.; Jiang, B.; Wang, K.; Deng, S.; Fan, C.; Li, D. Nanoplasmonic Imaging of Latent Fingerprints and Identification of Cocaine. Angew. Chem. Int. Ed. 2013, 52 (44), 11542-11545. (4) Qin, L.-X.; Li, Y.; Li, D.-W.; Jing, C.; Chen, B.-Q.; Ma, W.; Heyman, A.; Shoseyov, O.; Willner, I.; Tian, H.; Long, Y.-T. Electrodeposition of Single-Metal Nanoparticles on Stable Protein 1 Membranes: Application of Plasmonic Sensing by Single Nanoparticles. Angew. Chem. Int. Ed. 2012, 51 (1), 140-144. (5) Choi, Y.; Park, Y.; Kang, T.; Lee, L. P. Selective and sensitive detection of metal ions by plasmonic resonance energy transfer-based nanospectroscopy. Nat. Nanotechnol.2009, 4 (11), 742-746. (6) Fierro-Gonzalez, J. C.; Gates, B. C. Evidence of active species in CO oxidation catalyzed by highly dispersed supported gold. Catal. Today 2007, 122 (3–4), 201-210. (7) Shi, L.; Jing, C.; Ma, W.; Li, D.-W.; Halls, J. E.; Marken, F.; Long, Y.-T. Plasmon Resonance Scattering Spectroscopy at the Single-Nanoparticle Level: Real-Time Monitoring of a Click Reaction. Angew. Chem. Int. Ed. 2013, 52 (23), 6011-6014.
(8) Wang, J.-G.; Fossey, J. S.; Li, M.; Xie, T.; Long, Y.-T. RealTime Plasmonic Monitoring of Single Gold Amalgam Nanoalloy Electrochemical Formation and Stripping. ACS Appl. Mater. Interface 2016, 8 (12), 8305-8314. (9) Zhang, X.; Wei, M.; Lv, B.; Liu, Y.; Liu, X.; Wei, W., Sensitive colorimetric detection of glucose and cholesterol by using Au@Ag core-shell nanoparticles. RSC Adv. 2016, 6 (41), 3500135007. (10) Fei, K.; Xiangshu, H.; Kun, X., Highly sensitive colorimetric detection of glucose in a serum based on DNA-embeded Au@Ag core–shell nanoparticles. Nanotechnology 2015, 26 (40), 405707. (11) Zeng, J.-B.; Fan, S.-G.; Zhao, C.-Y.; Wang, Q.-R.; Zhou, T.Y.; Chen, X.; Yan, Z.-F.; Li, Y.-P.; Xing, W.; Wang, X.-D. A colorimetric agarose gel for formaldehyde measurement based on nanotechnology involving Tollens reaction. Chem. Commun. 2014, 50 (60), 8121-8123. (12) Li, T.; Zhu, K.; He, S.; Xia, X.; Liu, S.; Wang, Z.; Jiang, X., Sensitive detection of glucose based on gold nanoparticles assisted silver mirror reaction. Analyst 2011, 136 (14), 2893-2896. (13) Xianyu, Y.; Sun, J.; Li, Y.; Tian, Y.; Wang, Z.; Jiang, X., An ultrasensitive, non-enzymatic glucose assay via gold nanorod-assisted generation of silver nanoparticles. Nanoscale 2013, 5 (14), 6303-6306. (14) Dmitriev, A. Nanoplasmonic Sensors. 1st ed.; Springer-Verlag New York: 2012. (15) Silva, T. G.; de Araujo, W. R.; Muñoz, R. A. A.; Richter, E. M.; Santana, M. H. P.; Coltro, W. K. T.; Paixão, T. R. L. C., Simple and Sensitive Paper-Based Device Coupling Electrochemical Sample Pretreatment and Colorimetric Detection. Anal. Chem. 2016, 88 (10), 5145-5151. (16) Wang, Q.; Zhang, L.; Shang, C.; Zhang, Z.; Dong, S., Tripleenzyme mimetic activity of nickel-palladium hollow nanoparticles and their application in colorimetric biosensing of glucose. Chem. Commun. 2016, 52 (31), 5410-3. (17) Jing, C.; Gu, Z.; Ying, Y.-L.; Li, D.-W.; Zhang, L.; Long, Y.T. Chrominance to Dimension: A Real-Time Method for Measuring the Size of Single Gold Nanoparticles. Anal. Chem. 2012, 84 (10), 4284-4291. (18) Chirea, M.; Collins, S. S. E.; Wei, X.; Mulvaney, P. Spectroelectrochemistry of Silver Deposition on Single Gold Nanocrystals. J. Phys. Chem. Lett. 2014, 5 (24), 4331-4335. (19) Becker, J.; Zins, I.; Jakab, A.; Khalavka, Y.; Schubert, O.; Sönnichsen, C. Plasmonic Focusing Reduces Ensemble Linewidth of Silver-Coated Gold Nanorods. Nano Lett. 2008, 8 (6), 1719-1723. (20) Rodríguez-Lorenzo, L.; de la Rica, R.; Álvarez-Puebla, R. A.; Liz-Marzán, L. M.; Stevens, M. M. Plasmonic nanosensors with inverse sensitivity by means of enzyme-guided crystal growth. Nat. Mater. 2012, 11 (7), 604-607. (21) Cantarow, A.; Schepartz, B. Biochemistry. 2nd ed.; Philadelphia, Pa. ; London : Saunders: 1957. (22) Lin, S. D.; Su, S. L.; Wang, S. Y.; Tu, S. T.; Hsu, S. R. Using continuous glucose monitoring to assess contributions of premeal and postmeal glucose levels in diabetic patients treated with metformin alone. Diabetes Metab. DOI:http://dx.doi.org/10.1016/j.diabet.2016. 03.002. (23) Shiramoto, M.; Eto, T.; Irie, S.; Fukuzaki, A.; Teichert, L.; Tillner, J.; Takahashi, Y.; Koyama, M.; Dahmen, R.; Heise, T.; Becker, R. H. A. Single-dose new insulin glargine 300 U/ml provides prolonged, stable glycaemic control in Japanese and European people with type 1 diabetes. Diabetes Obes. Metab. 2015, 17 (3), 254-260. (24) Chorfi, Y.; Lanevschi-Pietersma, A.; Girard, V.; Tremblay, A., Evaluation of variation in serum globulin concentrations in dairy cattle. Veterinary Clinical Pathology 2004, 33 (3), 122-127.
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