Portable Fluorimeter Research Articles

Acoustic pipette and biofunctional elastomeric microparticle system for rapid picomolar-level biomolecule detection in whole blood.

Most biosensing techniques require complex processing steps that generate prolonged workflows and introduce potential points of error. Here, we report an acoustic pipette to purify and label biomarkers in 70 minutes. A key aspect of this technology is the use of functional negative acoustic contrast particles (fNACPs), which display biorecognition motifs for the specific capture of biomarkers from whole blood. Because of their large size and compressibility, the fNACPs robustly trap along the pressure antinodes of a standing wave and separate from blood components in under 60 seconds with >99% efficiency. fNACPs are subsequently fluorescently labeled in the pipette and are analyzed by both a custom, portable fluorimeter and flow cytometer. We demonstrate the detection of anti-ovalbumin antibodies from blood at picomolar levels (35 to 60 pM) with integrated controls showing minimal nonspecific adsorption. Overall, this system offers a simple and versatile approach for the rapid, sensitive, and specific capture of biomolecules.

Towards Onsite Age Estimation of Semen Stains Using Fluorescence Spectroscopy.

The age estimation of biological traces is one of the holy grails in forensic investigations. We developed a method for the age estimation of semen stains using fluorescence spectroscopy in conjunction with a stoichiometric ageing model. The model describes the degradation and generation rate of proteins and fluorescent oxidation products (FOX) over time. The previously used fluorimeter is a large benchtop device and requires system optimization for forensic applications. In situ applications have the advantage that measurements can be performed directly at the crime scene, without additional sampling or storage steps. Therefore, a portable fiber-based fluorimeter was developed, consisting of two optimized light-emitting diodes (LEDs) and two spectrometers to allow the fluorescence protein and FOX measurements. The handheld fiber can be used without touching the traces, avoiding the destruction or contamination of the trace. In this study, we have measured the ageing kinetics of semen stains over time using both our portable fluorimeter and a laboratory benchtop fluorimeter and compared their accuracies for the age estimation of semen stains. Successful age estimation was possible up to 11 days, with a mean absolute error of 1.0 days and 0.9 days for the portable and the benchtop fluorimeters, respectively. These results demonstrate the potential of using the portable fluorimeter for in situ applications.

Crystallization-induced emission enhancement of alkyl chain-dependent pyrene-based luminogens: Visual detection of nitro-explosives

In view of the widespread applications and urgent need for efficient blue emitting materials, the synthesis of such materials has seen renewed interest. In the present work, three alkyl chain-dependent blue emitting pyrene-based luminogens were synthesized and characterized. The experimental results show that these luminogens exhibited high photoluminescence efficiency both in solution (>86%) and in the solid state (>35%). Interestingly, 1,3,6,8-tetrakis (pentylphenyl)pyrene (TPPy), as a photoelectric functional material, was endowed with higher quantum yield (72%) and competitiveness due to a remarkable crystallization-induced emission enhancement (CIEE) property. More importantly, TPPy exhibits high sensitivity and selectivity for ortho-nitroaniline (o-NA) with low limit of detection (9.99 × 10−8 M), which is mainly due to the distinctive odd-even effects of the terminal alkyl chain. The results demonstrate that this type of luminogen can potentially be utilized for practical applications in the field of contaminant or explosive detection as a sensitive and portable fluorimeter.

UV-Excited Fluorescence as a Basis for the In-Situ Identification of Natural Binders in Historical Painting: A Critical Study on Model Samples

The fluorescence emission by aged organic binders used in painting is a well-known phenomenon. Several literature studies were devoted to its investigation, both on pure binders and on their mixtures with some pigments. Nevertheless, a systematic study about the real possibility of exploiting such a phenomenon for the non-invasive identification of binders in ancient paintings is still lacking. In the present work, a prototype portable fluorimeter was used to analyze a significant number of model painting samples containing different binders (drying oils, egg yolk, milk, animal glue, and gum Arabic) mixed with various pigments having different hues. The model samples were naturally aged in a period ranging from fifteen to one year. The effects on the spectral pattern due to the different binders, the recipes used to prepare them, and the pigments mixed with them were examined. The fluorescence spectra were corrected for the absorption of the emitted radiation due to the pigments. Finally, the corrected spectra were treated by principal component analysis to determine if the possibility of distinguishing at least the most fluorescent and common binders, i.e., drying oils and egg, existed. It was shown that, even if the technique cannot be effectively applied in the case of mixed or superimposed binders, it allows to put forward at least a preliminary hypothesis when pure binders are used.

Development of a Novel Benzimidazole-Based Probe and Portable Fluorimeter for the Detection of Cysteine in Human Urine.

The measurement of cysteine in human urine and live cells is crucial for evaluating biological metabolism, monitoring and maintaining the immune system, preventing tissue/DNA damage caused by free radicals, preventing autoimmune diseases, and diagnosing disorders such as cystinuria and cancer. A method that uses a fluorescence turn-on probe and a portable fluorescence spectrometer device are crucial for highly sensitive, simple, rapid, and inexpensive cysteine detection. Herein, we present the synthesis and application of a benzimidazole-based fluorescent probe (ABIA) along with the design and development of a portable fluorescence spectrometer device (CysDDev) for detecting cysteine in simulated human urine. ABIA showed excellent selectivity and sensitivity in detecting cysteine over homocysteine, glutathione, and other amino acids with the response time of 1 min and demonstrated a detection limit of 16.3 nM using the developed CysDDev. Further, ABIA also demonstrated its utility in detecting intracellular cysteine, making it an excellent probe for bio-imaging assay.

“Aptamer-locker” DNA coupling with CRISPR/Cas12a-guided biosensing for high-efficiency melamine analysis

Herein, we report a method that combined “aptamer-locker” DNA with CRISPR/Cas12a-based biosensing for sensitive and rapid melamine analysis. Three strategies were harnessed for designing the DNA sensors that were well characterized by circular dichroism (CD) spectroscopy and isothermal titration calorimetry (ITC) in the absence and presence of melamine. The detection parameters were optimized to achieve good analytic performance. As a result, a limit of detection (LOD) as low as 38 nM was achieved, which is below the threshold (1.0 mg/kg) of allowable melamine in infant milk products. In addition, the sensors show high selectivity for melamine against other analogues such as cyanuric acid, ammeline and ammelide. Moreover, our method was effective for rapid melamine analysis in whole milk samples, with or without sample pretreatment, in less than 20 min. Adopting a commercially available portable fluorimeter, on-site analysis of melamine in milk was accomplished. The strategies demonstrated here can expand to detect other non-nucleic-acid targets by simply replacing the aptamers.

Inexpensive Near-Infrared Fluorimeters: Enabling Translation of nIR-Based Assays to the Field.

The practical impact of analytical probes that transduce in the near-infrared (nIR) has been dampened by the lack of cost-effective and portable nIR fluorimeters. Herein, we demonstrate straightforward designs for an inexpensive microplate reader and a portable fluorimeter. These instruments require minimally complex machining and fabrication and operate with an open-source programming language (Python). Complete wiring diagrams, assembly diagrams, and scripts are provided. To demonstrate the utility of these two instruments, we performed high-throughput and field-side measurements of soil samples to evaluate the effect of soil management strategies on extracellular proteolytic, cellulolytic, and lignin-modifying activities. This was accomplished with fluorescent enzyme probes that utilized uniquely sensitive transducers exclusive to the nIR spectrum, single-walled carbon nanotubes. We also used the portable fluorimeter to evaluate spatial variations of proteolytic activity within individual field plots, while minimizing the effects of soil storage and handling. These demonstrations indicate the utility of these fluorimeters for translating analytical probes that operate in the nIR beyond the laboratory and into actual use.

One-Step Synthesized ZnO np-Based Optical Sensors for Detection of Aldicarb via a Photoinduced Electron Transfer Route.

Pesticides are used in agriculture for crop production enhancement by controlling pests, but they have acute toxicological effects on other life forms. Thus, it becomes imperative to detect their concentration in food products in a fast and accurate manner. In this study, ZnO nanoparticles (ZnO nps) have been used as optical sensors for the detection of pesticide Aldicarb via a photoinduced electron transfer (PET) route. ZnO nps were synthesized directly by calcining zinc acetate at 450, 500, and 550 °C for 2 h. ZnO nps were characterized by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), and UV–vis absorption and photoluminescence (PL) spectroscopies to study the phase, crystallinity, shape, morphology, absorbance, and fluorescence of the prepared ZnO nps. XRD and Raman studies confirmed the crystalline nature of ZnO nps. The average crystallite size obtained was 13–20 nm from the XRD study. The SEM study confirmed spherical-shaped ZnO nps with average sizes in the range of 70–150 nm. The maximum absorbance was obtained in the 200–500 nm regions with a prominent peak absorbance at 372 nm from UV–vis spectra. The corresponding band gap for ZnO nps was calculated using Tauc’s plots and was found to be 3.8, 3.67, and 3.45 eV for the 450, 500, and 550 °C calcined samples, respectively. The fluorescence spectra showed an increase in the intensity along with the increase in the size of ZnO nps. The ZnO nps (samples calcined at 500 and 550 °C) exhibited a response toward Aldicarb, owing to their pure phase and higher PL intensity. Both the samples showed systematic detection of Aldicarb in the range of 250 pM to 2 nM (500 °C) and 250 pM to 5 nM (550 °C). Among the various quenching mechanisms, PET was found to be the dominant process for the detection of Aldicarb. This method can be used for the detection of Aldicarb in real (food) samples using a portable fluorimeter.

Procedure to build a signal transfer set, independent of the target analytes, between a portable fluorimeter based on light-emitting diodes and a master fluorimeter

The need of performing “in situ” analytical determinations together with the availability of high-power deep UV-LEDs have led to the use of fluorescence spectroscopy. However, it is necessary to register excitation-emission matrices (EEM) to obtain three-way data which can be decomposed using parallel factor analysis for enabling the unequivocal identification of the analytes. In this context, the feasibility of transferring EEM between a portable fluorimeter based on LEDs and a master fluorimeter based on a xenon source has been recently reported without losing analytical quality.To build the transfer function, the signals of the same N samples must be recorded in the portable and in the master fluorimeter. In literature, these samples always contained the target analytes so the EEM signal transfer methodology is very limited in practice. Therefore, the challenge is to search for a set of samples whose EEM enable to perform the signal transfer without previously knowing the target analytes.The aim of this work is the design of a procedure to build N mixtures of P fluorophores so the N EEM would be optimal for the signal transfer. Five criteria have been defined a priori to identify the quality of a transfer set made up of N EEM. Then, a procedure has been designed to obtain the n mixtures of the P fluorophores “in silico” using the Pareto front of the optimal solutions and a desirability function to choose the desired N EEM.The procedure has been used to find five mixtures of the three chosen fluorophores for the signal transfer (coumarin 120, DL-Tyrosine and DL-Tryptophan) which are chemically different from the analytes of interest (enrofloxacin and flumequine) and are contained in a different matrix. These two analytes are antibiotics which have maximum residue limits set in the EU legislation in force.The correlation coefficients between the experimental reference spectra and the PARAFAC spectral loadings of the data registered with the master fluorimeter were greater than or equal to 0.999 in all cases. On the other hand, the correlation coefficients obtained with the portable fluorimeter ranged from 0.900 to 0.950 once the procedure was applied to the two antibiotics. Therefore, the unequivocal identification of the analytes was ensured.

Pyrene-Based Chemosensor for Picric Acid-Fundamentals to Smartphone Device Design.

Developing a fluorescent probe for the selective and sensitive detection of explosives is a topic of continuous research interest. Additionally, underlying the principles behind the detection mechanism is indeed providing substantial information about the design of an efficient fluorescence probe. In this context, a pyrene-tethered 1-(pyridin-2-yl)imidazo[1,5-a]pyridine-based fluorescent probe (TL18) was developed and employed as a fluorescent chemosensor for nitro explosives. The molecular structure of TL18 was well-characterized by NMR and EI-MS spectrometric techniques. UV-visible absorption, steady-state, and time-resolved fluorescence spectroscopic techniques have been employed to explicate the photophysical properties of TL18. The fluorescent nature of the TL18 probe was explored for detection of nitro explosives. Intriguingly, the TL18 probe was selectively responsive to picric acid over other explosives. The quantitative analysis of the fluorescence titration studies of TL18 with picric acid proved that the probe achieved a detection limit of 63 nM. Further, DFT and QTAIM studies were used to establish the nature of the sensing mechanism of TL18. The hydrogen-bonding interactions are the reason for the imperative sensing property of TL18 for picric acid. Thus, our experimental and theoretical studies provide an adequate and appropriate prerequisite for an efficient fluorescent probe. Furthermore, a smartphone-interfaced portable fluorimeter module is developed to facilitate sensitive and real-time sensing of picric acid. This portable module was capable of detecting picric acid down to 99 nM. Eventually, these studies will have a significant impact on development and application of a new class of chemosensors for detection of explosives.

A Low-Cost and Portable Smart Instrumentation for Detecting Colorectal Cancer Cells

Fluorescence imaging is a well-known method for monitoring fluorescence emitted from the subject of interest and provides important insights about cell dynamics and molecules in mammalian cells. Currently, many solutions exist for measuring fluorescence, but the application methods are complex and the costs are high. This paper describes the design and development of a low-cost, smart and portable fluorimeter for the detection of colorectal cancer cell expressing IRFP702. A flashlight is used as a light source, which emits light in the visible range and acts as an excitation source, while a photodiode is used as a detector. It also uses a longpass filter to only allow the wavelength of interest to pass from the cultured cell. It eliminates the need of both the dichroic mirror and excitation filter, which makes the developed device low cost, compact and portable as well as lightweight. The custom-built sample chamber is black in color to minimize interference and is printed with a 3D printer to accommodate the detector circuitry. An established colorectal cancer cell line (human colorectal carcinoma (HCT116)) was cultured in the laboratory environment. A near-infrared fluorescent protein IRFP702 was expressed in the colorectal cancer cells that were used to test the proof-of-concept. The fluorescent cancer cells were first tested with a commercial imaging system (Odyssey® CLx) and then with the developed prototype to validate the result in a preclinical setting. The developed fluorimeter is versatile as it can also be used to detect multiple types of cancer cells by simply replacing the filters based on the fluorophore.

Integrating spatial variations in the vineyard to enhance quantitative trait locus (QTL) detection

French vineyards are often located on the least fertile lands, generally more heterogeneous than lands devoted to food crops. The detection of quantitative trait loci (QTLs) is all the more precise, as the number of genotypes studied is high, but increasing the size of experimental plots means taking the risk of exploring more spatial heterogeneity. Designing randomized blocks experiments is a classical way to overcome this difficulty. However, when several hundred genotypes are studied, this not only requires more land but is also time consuming. Another approach is to take into account the spatial heterogeneity when searching for QTLs. We performed QTL detection for variables corrected for spatial heterogeneity in the progeny of a 'Riesling' (RI) × 'Gewurztraminer' (GW) cross to evaluate the potential of such an approach. We show that mapping methods can improve QTL detection for grapevine water status (δ 13 C) and pruning weight. QTLs for vegetative indices measured with the portable fluorimeter Multiplex ® were, however, not better detected after taking into account the spatial heterogeneity. This study shows that QTL detection can be improved when correcting raw data for spatial heterogeneity.

Signal transfer with excitation-emission matrices between a portable fluorimeter based on light-emitting diodes and a master fluorimeter

In this work, the transfer of the excitation-emission matrices between a portable fluorimeter based on LEDs and a master fluorimeter based on a xenon source was carried out. Enrofloxacin was the analyte of interest and it was measured alone or in binary mixtures with flumequine (partially overlapped signals) or with ciprofloxacin (fully overlapped signals). The maintenance and transfer of the unequivocal identification of the fluorophores between both instruments are shown. The precision in the determination performed with the portable fluorimeter approximated to that made with the master fluorimeter using this transfer and it did not introduce bias. The correlation coefficients of the calibrations based on PARAFAC using EEM signals were higher than 0.999, whereas the values of the capability of detection ranged from 14.8 to 26.9 μg L−1 for probabilities of false positive and false negative fixed at 0.05. These results contribute to the effort to perform the fluorimetric detection outside the laboratory and to promote the use of databases of fluorescence spectra for the unequivocal identification in remote of fluorophores of interest and/or regulated.

Xurography-based microfluidic algal biosensor and dedicated portable measurement station for online monitoring of urban polluted samples

A critical need exists to develop rapid, in situ, and real-time tools to monitor the impact of pollution discharge toxicity on aquatic ecosystems. The present paper deals with the development of a novel, simple-to-use, low-cost, portable, and user-friendly algal biosensor. In this study, a complete and autonomous portable fluorimeter was developed to assess the A-chlorophyll fluorescence of microalgae, inserted by capillarity into low-cost and disposable xurography-based microfluidic chips. Three microalgae populations were used to develop the biosensor: Chlorella vulgaris, Pseudokirchneriella subcapitata, and Chlamydomonas reinhardtii. Biosensor feasibility and sensitivity parameters, such as algal concentration and light intensity, were optimized beforehand to calibrate the biosensor sensitivity with Diuron, a pesticide known to be very toxic for microalgae. Finally, the biosensor was employed in 10 aqueous urban polluted samples (7 urban wet-weather discharges and 3 wastewater) in order to prove its reliability, reproducibility, and performance in the detection of toxic discharges in the field.

Development of a biosensor protein bullet as a fluorescent method for fast detection of Escherichia coli in drinking water.

Drinking water can be exposed to different biological contaminants from the source, through the pipelines, until reaching the final consumer or industry. Some of these are pathogenic bacteria and viruses which may cause important gastrointestinal or systemic diseases. The microbiological quality of drinking water relies mainly in monitoring three indicator bacteria of faecal origin, Escherichia coli, Enterococcus faecalis and Clostridium perfringens, which serve as early sentinels of potential health hazards for the population. Here we describe the analysis of three chimeric fluorescent protein bullets as biosensor candidates for fast detection of E. coli in drinking water. Two of the chimeric proteins (based on GFP-hadrurin and GFP-pb5 chimera proteins) failed with respect to specificity and/or sensitivity, but the GFP-colS4 chimera protein was able to carry out specific detection of E. coli in drinking water samples in a procedure encompassing about 8 min for final result and this biosensor protein was able to detect in a linear way between 20 and 103 CFU of this bacterium. Below 20 CFU, the system cannot differentiate presence or absence of the target bacterium. The fluorescence in this biosensor system is provided by the GFP subunit of the chimeric protein, which, in the case of the better performing sensor bullet, GFP-colS4 chimera, is covalently bound to a flexible peptide bridge and to a bacteriocin binding specifically to E. coli cells. Once bound to the target bacteria, the excitation step with 395 nm LED light causes emission of fluorescence from the GFP domain, which is amplified in a photomultiplier tube, and finally this signal is converted into an output voltage which can be associated with a CFU value and these data distributed along mobile phone networks, for example. This method, and the portable fluorimeter which has been developed for it, may contribute to reduce the analysis time for detecting E. coli presence in drinking water.

Retail Sugar From One Zambian Community Does Not Meet Statutory Requirements for Vitamin A Fortification.

Industrial food fortification is a major strategy to improve dietary micronutrient intakes and prevent deficiencies. Zambia introduced mandatory sugar fortification with vitamin A, at a target of 10 mg/kg, in 1998. Representative surveys conducted since that time do not support marked improvement in vitamin A status. To describe vitamin A concentrations in retail sugar, as well as vendor practices, perceptions of fortified foods, and sugar use practices. We conducted a census of sugar vendors in one Zambian community, capturing information on vendors, available brands and packaging options, and storage conditions. We purchased all brands and package types of sugar available at each vendor. In a 15% subsample, we conducted semi-structured interviews with vendor-consumer pairs. We tested 50% of sugar samples at random for vitamin A using an iCheck portable fluorimeter. The distribution of vitamin A in sugar in market samples was highly skewed, with a median of 3.1 mg/kg (25th-75th percentiles: 1.8-5.5) and a range from 0.2 to 29.9 mg/kg. Only 11.3% of samples met the 10 mg/kg statutory requirement. Sugar was primarily repackaged and sold in small quantities, with rapid turnover of stocks. Perceptions of fortification by vendors and consumers were generally positive. Vitamin A in fortified sugar fell well below statutory requirements. Our data point to challenges at regional depot and/or poor adherence to fortification standards at the factory level. A renewed commitment to monitoring and enforcement will be required for Zambia to benefit from a food fortification strategy.

A facile and high sensitive micro fluorimeter based on light emitting diode and photodiode

A facile and high sensitive micro fluorimeter was developed and evaluated. It employed light emitting diode (LED) as light source, cuvette as detection cell, and photodiode (PD) as optoelectronic detector. Optical and electronic parameters were optimized and demonstrated. A high power LED was chosen, which could irradiate the inner area of the cuvette completely at the same time with divergence angle as small as possible. The optimum LED brought 2.5 times signal-to-noise ratio (SNR) enhancement. Using reflector at the opposite direction of excitation light path doubled SNR. The amplifier circuit of PD was deeply investigated to achieve high sensitivity, low noise, and good stability. The limit of detection (LOD) of fluorescein isothiocyanate (FITC) and chlorophyll at SNR = 3 were 10pM ~ 0.004 ppb and 0.05 ppb, respectively. Basing on the principle structure, a portable fluorimeter for fungimycin detection was developed using a low power UV LED as light source. The LOD for aflatoxin B1 was 0.1 ppb.

To what extent can portable fluorescence spectroscopy be used in the real-time assessment of microbial water quality?

The intrinsic fluorescence of aquatic organic matter emitted at 350nm when excited at 280nm correlates widely with water quality parameters such as biochemical oxygen demand. Hence, in sewage-impacted rivers and groundwater, it might be expected that fluorescence at these wavelengths will also correlate with the microbial water quality. In this paper we use a portable fluorimeter to assess the relationship between fluorescence intensity at this wavelength pair and Escherichia coli enumeration in contrasting river catchments of poor water quality: in KwaZulu-Natal, S. Africa and the West Midlands, UK. Across all catchments we demonstrate a log correlation (r=0.74) between fluorescence intensity and E. coli over a seven-log range in E. coli enumerations on non-perturbed (unfiltered) samples. Within specific catchments, the relationship between fluorescence intensity and E. coli is more variable, demonstrating the importance of catchment-specific interference. Our research demonstrates the potential of using a portable fluorimeter as an initial screening tool for indicative microbial water quality, and one that is ideally suited to simple pollution scenarios such as assessing the impact of faecal contamination in river or groundwater at specific sites.

Application of portable fluorescence spectrophotometry for integrity testing of recycled water dual distribution systems.

Water utilities supplying recycled water to households via a "third-pipe" or "dual reticulation" system have a need for a rapid, portable method to detect cross-connections within potable water reticulation networks. This study evaluates portable fluorimetry as a technique for cross-connection detection in the field. For the first time, an investigation of a full-scale dual reticulation water-recycling network has been carried out to identify cross-connections using a portable fluorimeter. We determined that this can be carried out with a 3 mL water sample, and unlike methods that are currently in use for cross-connection detection, can be achieved quickly without disruption to water flow or availability within the network. It was also revealed that fluorescence trigger values could be established with high levels of confidence by sampling less than 2.5% of the network. Fluorescence analysis was also able to uncover a single, real cross-connection event. As such, this paper is a fundamental demonstration of fluorescence as a reliable, highly portable technique for cross-connection detection within dual reticulation water recycling networks and further establishes the abilities of fluorescence devices as valuable field instruments for water quality monitoring.

In field non-invasive sensing of the nitrogen status in hybrid bermudagrass (Cynodon dactylon × C. transvaalensis Burtt Davy) by a fluorescence-based method

The level of N fertilization and the content of leaf N in Cynodon dactylon × C. transvaalensis Burtt Davy cv. ‘Tifway 419’ bermudagrass were evaluated non-destructively with a fluorescence-based method. It was applied directly into the field by using the Multiplex portable fluorimeter during two consecutive seasons (2010 and 2011). In the 2010 experiment, the nitrogen balance index (NBI1) provided by the sensor was able to discriminate (at P<0.05) six different N levels applied, up to 250kgha−1, with a precision (root mean square error, RMSE) in the rate estimate of 3.29kgha−1. In 2011, the index was insensitive to the N treatment between 150kgha−1 and 250kgha−1 N rates, and its precision was 39.98kgha−1. Calibration of the sensor by using the destructive analysis of turf samplings showed a good linear regression between NBI1 and the leaf N content for both 2010 (R2=0.81) and 2011 (R2=0.93) experiments. This allowed mapping of the leaf N spatial distribution acquired by the sensor in the field with a prediction error of 0.21%. Averaging the overall estimates of leaf N content per N treatment provided an upper limit of 200kgha−1 for the required fertilization, corresponding to a critical level of leaf N of about 2.3%. Our results confirm the usefulness of the new fluorescence-based method and sensor for a precise management of fertilization in turfgrass.