An optofluidic system for the concentration gradient screening of oocyte protection drugs.

Oocytes protective drug screening is essential for the treatment of reproductive diseases. However, few studies construct the oocyte in vitro drug screening microfluidic systems because of their enormous size, scarcity, and sensitivity to the culture environment. Here, we present an optofluidic system for oocyte drug screening and state analysis. The system consists of two parts: an open-top drug screening microfluidic chip and an optical Fourier filter analysis part. The open-top microfluidic chip anchors single oocyte with hydrogel and allows nutrient and gas environment updating which is essential for oocyte culturing. The optical filter analysis part is used to accurately analyse the status of oocytes. Based on this system, we found that fluorene-9-bisphenol (BHPF) damaged the oocyte spindle in a dose-dependent manner, a high dose of melatonin (10-3 M) effectively reduces the percentage of abnormally arranged chromosomes of oocytes exposed to 40 µM BHPF. This optofluidic system shows great promise for the culture of oocytes and demonstrates the robust ability for convenient multi-concentration oocytes drug screening. This technology may benefit further biomedicine and reproductive toxicology applications in the lab on a chip community.

Acoustic Assembly and Scanning of Superlens Arrays for High-Resolution and Large Field-of-View Bioimaging.

High-resolution and dynamic bioimaging is essential in life sciences and biomedical applications. In recent years, microspheres combined with optical microscopes have offered a low cost but promising solution for super-resolution imaging, by breaking the diffraction barrier. However, challenges still exist in precisely and parallelly superlens controlling using a noncontact manner, to meet the demands of large-area scanning imaging for desired targets. This study proposes an acoustic wavefield-based strategy for assembling and manipulating micrometer-scale superlens arrays, in addition to achieving on-demand scanning imaging through phase modulation. In experiments, acoustic pressure nodes are designed to be comparable in size to microspheres, allowing spatially dispersed microspheres to be arranged into arrays with one unit per node. Droplet microlenses with various diameters can be adapted in the array, allowing for a wide range of spacing periods by applying different frequencies. In addition, through the continuous phase shifting in the x and y directions, this acoustic superlens array achieves on-demand moving for the parallel high-resolution virtual image capturing and scanning of nanostructures and biological cell samples. As a comparison, this noncontact and cost-effective acoustic manner can obtain more than ∼100 times the acquisition efficiency of a single lens, holding promise in advancing super-resolution microscopy and subcellular-level bioimaging.

Geometric phase-encoded stimuli-responsive cholesteric liquid crystals for visualizing real-time remote monitoring: humidity sensing as a proof of concept.

Liquid crystals are a vital component of modern photonics, and recent studies have demonstrated the exceptional sensing properties of stimuli-responsive cholesteric liquid crystals. However, existing cholesteric liquid crystal-based sensors often rely on the naked eye perceptibility of structural color or the measurement of wavelength changes by spectrometric tools, which limits their practical applications. Therefore, developing a platform that produces recognizable sensing signals is critical. In this study, we present a visual sensing platform based on geometric phase encoding of stimuli-responsive cholesteric liquid crystal polymers that generates real-time visual patterns, rather than frequency changes. To demonstrate this platform's effectiveness, we used a humidity-responsive cholesteric liquid crystal polymer film encoded with a q-plate pattern, which revealed that humidity causes a shape change in the vortex beam reflected from the encoded cholesteric liquid crystal polymers. Moreover, we developed a prototype platform towards remote humidity monitoring benefiting from the high directionality and long-range transmission properties of laser beams carrying orbital angular momentum. Our approach provides a novel sensing platform for cholesteric liquid crystals-based sensors that offers promising practical applications. The ability to generate recognizable sensing signals through visual patterns offers a new level of practicality in the sensing field with stimuli-responsive cholesteric liquid crystals. This platform might have significant implications for a broad readership and will be of interest to researchers working in the field of photonics and sensing technology.

Acoustic quasi-periodic bioassembly based diverse stem cell arrangements for differentiation guidance.

Arrangement patterns and geometric cues have been demonstrated to influence cell function and fate, which calls for efficient and versatile cell patterning techniques. Despite constant achievements that mainly focus on individual cells and uniform cell patterns, simultaneously constructing cellular arrangements with diverse patterns and positional relationships in a flexible and contact-free manner remains a challenge. Here, stem cell arrangements possessing multiple geometries and structures are proposed based on powerful and diverse pattern-building capabilities of quasi-periodic acoustic fields, with advantages of rich patterns and structures and flexibility in structure modulation. Eight-fold waves' interference produces regular potentials that result in higher rotational symmetry and more complex arrangement of geometric units. Moreover, through flexible modulation of the phase relations among these wave vectors, a wide variety of cellular pattern units are arranged in this potential, such as circular-, triangular- and square-shape, simultaneously. It is proved that these diverse cellular patterns conveniently build human mesenchymal stem cell (hMSC) models, for research on the effect of cellular arrangement on stem cell differentiation. This work fills the gap of acoustic cell patterning in quasi-periodic patterns and shows promising potential in tissue engineering and regenerative medicine.

Heterogeneous tissue construction by on-demand bubble-assisted acoustic patterning.

Highly heterogeneous structures are closely related to the realization of the tissue functions of living organisms. However, precisely controlling the assembly of heterogeneous structures is still a crucial challenge. This work presents an on-demand bubble-assisted acoustic method for active cell patterning to achieve high-precision heterogeneous structures. Active cell patterning is achieved by the combined effect of acoustic radiation forces and microstreaming around oscillating bubble arrays. On-demand bubble arrays allow flexible construction of cell patterns with a precision of up to 45 µm. As a typical example, the in vitro model of hepatic lobules, composed of patterned endothelial cells and hepatic parenchymal cells, was constructed and cultured for 5 days. The good performance of urea and albumin secretion, enzymatic activity and good proliferation of both cells prove the feasibility of this technique. Overall, this bubble-assisted acoustic approach provides a simple and efficient strategy for on-demand large-area tissue construction, with considerable potential for different tissue model fabrication.

Convenient tumor 3D spheroid arrays manufacturing via acoustic excited bubbles for in situ drug screening.

The quick and convenient fabrication of in vitro tumor spheroids models has been pursued for clinical drug discovery and personalized therapy. Here, uniform three-dimensional (3D) tumor spheroids are quickly constructed by acoustically excited bubble arrays in a microfluidic chip and performed drug response testing in situ. In detail, bubble oscillation excited by acoustic waves induces second radiation force, resulting in the cells rotating and aggregating into tumor spheroids, which obtain controllable sizes ranging from 30 to 300 µm. These spherical tumor models are located in microfluidic networks, where drug solutions with gradient concentrations are generated from 0 to 18 mg mL-1, so that the cell spheroids response to drugs can be monitored conveniently and efficiently. This one-step tumor spheroids manufacturing method significantly reduces the model construction time to less than 15 s and increases efficiency by eliminating additional transfer processes. These significant advantages of convenience and high-throughput manufacturing make the tumor models promising for use in tumor treatment and point-of-care diagnosis.

Tunable and Dynamic Optofluidic Microlens Arrays Based on Droplets.

Microlens arrays (MLAs) are acquiring a key role in the micro-optical system, which have been widely applied in the fields of imaging processing, light extraction, biochemical sensing, and display technology. Compared with solid MLAs, liquid MLAs have received extensive attention due to their natural smooth interface and adjustability. However, manufacturing tunable liquid MLAs with ideal structures is still a key challenge for current technologies. In this paper, a novel and simple optofluidic method is demonstrated, enabling the tunable focusing and high-quality imaging of liquid MLAs. Tunable droplets are fabricated and self-assembled into arrays as the MLAs, which can be easily adjusted to focus, form images, and display different focal lengths. Tuning of MLAs' focusing properties (range from 550 to 5370 µm) is demonstrated by changing the refractive index (RI) of the droplets with a fixed size of 200 µm, which can be changed by adjusting the flow rates of the two branch streams. Also, the corresponding numerical apertures of the MLAs range from 0.026 to 0.26. Furthermore, the MLAs' functionality for microparticle imaging applications is also illustrated. Combining the MLAs with a 4× objective, microparticle imaging is magnified two times, and the resolution has also been improved on the original basis. Besides, both the size and RI of the MLAs in an optofluidic chip can be further adjusted to detect samples at different positions. These MLAs have the merits of high optical performance, a simple fabrication procedure, easy integration, and good tunability. Thus, it shows promising opportunities for many applications, such as adaptive imaging and sensing.

On-demand liquid microlens arrays by non-contact relocation of inhomogeneous fluids in acoustic fields.

Microlens arrays (MLAs) are key micro-optical components that possess a high degree of parallelism and ease of integration. However, rapid and low-cost fabrication of MLAs with flexible focusing remains a challenge. Herein, liquid MLAs with dynamic tunability are presented using non-contact acoustic relocation of inhomogeneous fluids. By designing ring-shaped acoustic pressure node (PN) arrays, the denser fluid of miscible liquids is relocated to PNs, and liquid MLAs with ideal morphology are obtained. The experimental results demonstrate that the liquid MLAs possess a powerful reconfigurability with long-term stability and sharp imaging that can conveniently switch between the on and off state and can dynamically magnify by simply adjusting the acoustic amplitude. Moreover, the high biocompatibility inherited from liquids accompanied by the acoustic treatment allows cells to be within working distance of the MLAs without immersion, as would be required for a solid lens. This innovative liquid MLA is inexpensive to manufacture and possesses continuous focus, fast response, and satisfactory bioaffinity, and thus offers promising potential for microfluidic adaptive imaging and biomedical sensing, especially for live cell imaging.

Purification and Identification of a Novel Angiotensin Converting Enzyme Inhibitory Peptide from the Enzymatic Hydrolysate of Lepidotrigla microptera.

In this study, Lepidotrigla microptera were hydrolyzed with four different proteolytic enzymes (Papain, neutrase, flavourzyme, and alcalase), and their distribution of molecular weights and ACE-inhibitory activity were tested. The alcalase hydrolysates showed the maximum ACE-inhibitory activity. A novel ACE-inhibitory peptide was isolated and purified from Lepidotrigla microptera protein hydrolysate (LMPH) using ultrafiltration, gel filtration chromatography, and preparative high performance liquid chromatography (prep-HPLC). The amino acid sequence of the purified peptide was identified as Phe-Leu-Thr-Ala-Gly-Leu-Leu-Asp (DLTAGLLE), and the IC50 value was 0.13 mg/mL. The ACE-inhibitory activity of DLTAGLLE was stable across a range of temperatures (<100 °C) and pH values (3.0−11.0) and retained after gastrointestinal digestion. DLTAGLLE was further identified as a noncompetitive inhibitor by Lineweaver−Burk plot. The molecular docking simulation showed that DLTAGLLE showed a high binding affinity with ACE sites by seven short hydrogen bonds. As the first reported antihypertensive peptide extracted from alcalase hydrolysate of Lepidotrigla microptera, DLTAGLLE has the potential to develop functional food or novel ACE-inhibitor drugs.

Smart acoustic 3D cell construct assembly with high-resolution.

Precise and flexible three-dimensional (3D) cell construct assembly using external forces or fields can produce micro-scale cellular architectures with intercellular connections, which is an important prerequisite to reproducing the structures and functions of biological systems. Currently, it is also a substantial challenge in the bioengineering field. Here, we propose a smart acoustic 3D cell assembly strategy that utilizes a 3D printed module and hydrogel sheets. Digitally controlled six wave beams offer a high degree of freedom (including wave vector combination, frequency, phase, and amplitude) that enables versatile biomimetic micro cellular patterns in hydrogel sheets. Further, replaceable frames can be used to fix the acoustic-built micro-scale cellular structures in these sheets, enabling user-defined hierarchical or heterogeneous constructs through layer-by-layer assembly. This strategy can be employed to construct vasculature with different diameters and lengths, composed of human umbilical vein endothelial cells and smooth muscle cells. These constructs can also induce controllable vascular network formation. Overall, the findings of this work extend the capabilities of acoustic cell assembly into 3D space, offering advantages including innovative, flexible, and precise patterning, and displaying great potential for the manufacture of various artificial tissue structures that duplicatein vivofunctions.

Noninvasive Optical Isolation and Identification of Circulating Tumor Cells Engineered by Fluorescent Microspheres.

Circulating tumor cells (CTCs) are rare, meaning that current isolation strategies can hardly satisfy efficiency and cell biocompatibility requirements, which hinders clinical applications. In addition, the selected cells require immunofluorescence identification, which is a time-consuming and expensive process. Here, we developed a method to simultaneously separate and identify CTCs by the integration of optical force and fluorescent microspheres. Our method achieved high-purity separation of CTCs without damage through light manipulation and avoided additional immunofluorescence staining procedures, thus achieving rapid identification of sorted cells. White blood cells (WBCs) and CTCs are similar in size and density, which creates difficulties in distinguishing them optically. Therefore, fluorescent PS microspheres with high refractive index (RI) are designed here to capture the CTCs (PS-CTCs) and increase the average index of refraction of PS-CTCs. In optofluidic chips, PS-CTCs were propelled to the collection channel from the sample mixture, under the radiation of light force. Cells from the collection outlet were easily identified under a fluorescence microscope due to the fluorescence signals of PS microspheres. This method provides an approach for the sorting and identification of CTCs, which holds great potential for clinical applications in early diagnosis of disease.

Digital optofluidic compound eyes with natural structures and zooming capability for large-area fluorescence sensing.

Compound eyes are ubiquitous natural biosensors that possess high temporal resolution and large fields of view (FOVs). While for solid materials based artificial imaging systems, flexible zooming ability while keeping the constant FOV is still challenging, as well as the low-cost fabrication. Herein, liquid compound eyes with natural structures are presented that synthesize optofluidics and bionics in a non-trivial manner, which enables the deformation-free zooming and flexible cell fluorescence sensing. Experimental results indicate that the innovatively manufactured bionic template possesses low roughness and uniform lens configuration with more than two thousands units, which endows the eyes with high-quality and low aberration imaging ability. Besides, digital controlled miscible liquids switching enables the focus of ommatidia simultaneously be adjusted from 150 µm to 5 mm with 100° view angle, and without bending the microlens curvature, to avoid FOV changing and image aberration. Due to large FOV and tunable ability, large-area cell fluorescence signal arrays and dynamic cell motion are imaged using this liquid compound eyes. This work presents novel strategy for compound lens manufacture at low-cost, and proposes deformation-free and continuous focus-tuning strategy, offering potentials for numerous applications, including biomedical sensing and adaptive imaging with large FOV.

Touchable cell biophysics property recognition platforms enable multifunctional blood smart health care.

As a crucial biophysical property, red blood cell (RBC) deformability is pathologically altered in numerous disease states, and biochemical and structural changes occur over time in stored samples of otherwise normal RBCs. However, there is still a gap in applying it further to point-of-care blood devices due to the large external equipment (high-resolution microscope and microfluidic pump), associated operational difficulties, and professional analysis. Herein, we revolutionarily propose a smart optofluidic system to provide a differential diagnosis for blood testing via precise cell biophysics property recognition both mechanically and morphologically. Deformation of the RBC population is caused by pressing the hydrogel via an integrated mechanical transfer device. The biophysical properties of the cell population are obtained by the designed smartphone algorithm. Artificial intelligence-based modeling of cell biophysics properties related to blood diseases and quality was developed for online testing. We currently achieve 100% diagnostic accuracy for five typical clinical blood diseases (90 megaloblastic anemia, 78 myelofibrosis, 84 iron deficiency anemia, 48 thrombotic thrombocytopenic purpura, and 48 thalassemias) via real-world prospective implementation; furthermore, personalized blood quality (for transfusion in cardiac surgery) monitoring is achieved with an accuracy of 96.9%. This work suggests a potential basis for next-generation blood smart health care devices.

On-chip rapid drug screening of leukemia cells by acoustic streaming.

Rapid and personalized single-cell drug screening testing plays an essential role in acute myeloid leukemia drug combination chemotherapy. Conventional chemotherapeutic drug screening is a time-consuming process because of the natural resistance of cell membranes to drugs, and there are still great challenges related to using technologies that change membrane permeability such as sonoporation in high-throughput and precise single-cell drug screening with minimal damage. In this study, we proposed an acoustic streaming-based non-invasive single-cell drug screening acceleration method, using high-frequency acoustic waves (>10 MHz) in a concentration gradient microfluidic device. High-frequency acoustics leads to increased difficulties in inducing cavitation and generates acoustic streaming around each single cell. Therefore, single-cell membrane permeability is non-invasively increased by the acoustic pressure and acoustic streaming-induced shear force, which significantly improves the drug uptake process. In the experiment, single human myeloid leukemia mononuclear (THP-1) cells were trapped by triangle cell traps in concentration gradient chips with different cytarabine (Ara-C) drug concentrations. Due to this dual acoustic effect, the drugs affect cell viability in less than 30 min, which is faster than traditional methods (usually more than 24 h). This dual acoustic effect-based drug delivery strategy has the potential to save time and reduce the cost of drug screening, when combined with microfluidic technology for multi-concentration drug screening. This strategy offers enormous potential for use in multiple drug screening or efficient drug combination screening in individualized/personalized treatments, which can greatly improve efficiency and reduce costs.

A Phosphorescence Quenching-Based Intelligent Dissolved Oxygen Sensor on an Optofluidic Platform.

Continuous measurement of dissolved oxygen (DO) is essential for water quality monitoring and biomedical applications. Here, a phosphorescence quenching-based intelligent dissolved oxygen sensor on an optofluidic platform for continuous measurement of dissolved oxygen is presented. A high sensitivity dissolved oxygen-sensing membrane was prepared by coating the phosphorescence indicator of platinum(II) meso-tetrakis(pentafluorophenyl)porphyrin (PtTFPP) on the surface of the microfluidic channels composed of polydimethylsiloxane (PDMS) microstructure arrays. Then, oxygen could be determined by its quenching effect on the phosphorescence, according to Stern-Volmer model. The intelligent sensor abandons complicated optical or electrical design and uses a photomultiplier (PMT) counter in cooperation with a mobile phone application program to measure phosphorescence intensity, so as to realize continuous, intelligent and real-time dissolved oxygen analysis. Owing to the combination of the microfluidic-based highly sensitive oxygen sensing membrane with a reliable phosphorescent intensity detection module, the intelligent sensor achieves a low limit of detection (LOD) of 0.01 mg/L, a high sensitivity of 16.9 and a short response time (22 s). Different natural water samples were successfully analyzed using the intelligent sensor, and results demonstrated that the sensor features a high accuracy. The sensor combines the oxygen sensing mechanism with optofluidics and electronics, providing a miniaturized and intelligent detection platform for practical oxygen analysis in different application fields.

Rapid nitrate determination with a portable lab-on-chip device based on double microstructured assisted reactors.

Determining the nitrate levels is critical for water quality monitoring, and traditional methods are limited by high toxicity and low detection efficiency. Here, rapid nitrate determination was realized using a portable device based on innovative three-dimensional double microstructured assisted reactors (DMARs). On-chip nitrate reduction and chromogenic reaction were conducted in the DMARs, and the reaction products then flowed into a PMMA optical detection chip for absorbance measurement. A significant enhancement of reaction rate and efficiency was observed in the DMARs due to their sizeable surface-area-to-volume ratios and hydrodynamics in the microchannels. The highest reduction ratio of 94.8% was realized by optimizing experimental parameters, which is greatly improved compared to conventional zinc-cadmium based approaches. Besides, modular optical detection improves the reliability of the portable device, and a smartphone was used to achieve a portable and convenient nitrate analysis. Different water samples were successfully analysed using the portable device based on DMARs. The results demonstrated that the device features fast detection (115 s per sample), low reagent consumptions (26.8 µL per sample), particularly low consumptions of toxic reagents (0.38 µL per sample), good reproducibility and low relative standard deviations (RSDs, 0.5-1.38%). Predictably, the portable lab-on-chip device based on microstructured assisted reactors will find more applications in the field of water quality monitoring in the near future.

Identification of Potential Biomarkers of Polycystic Ovary Syndrome via Integrated Bioinformatics Analysis.

Polycystic ovary syndrome (PCOS) is a life-long reproductive, endocrine, and metabolic disorder that affects up to 17% of women of reproductive age. However, the effect of granulosa cells (GCs) transcriptome changes on oocyte capacity and follicular development in patients with PCOS has not been elucidated. This study aims to analyze transcriptome changes in GCs of PCOS from different perspectives and explore potential biomarkers for the diagnosis and treatment of PCOS. The gene expression profiles of GSE34526 and GSE107746 were obtained from the GEO database. Differentially expressed genes (DEGs) and key signaling pathways were identified. Gene Set Enrichment Analysis (GSEA) revealed that Toll-like receptors, NOD-like receptors, and NOTCH signaling pathways were obviously enriched in GCs of PCOS. We further analyzed DEGs from three aspects: transcription factors (TFs), secreted proteins, and follicular development. Compared with normal GCs, the DEGs encoding TFs and secretory proteins in GCs of PCOS remarkably changed. Besides, HAS2 and CBLN1, which are highly expressed in preovulatory follicular GCs and may trigger ovulation, were significantly decreased in GCs of PCOS. This study found candidate genes and signaling pathways in PCOS, providing new insights and foundations for the etiology of PCOS. Besides, HSA2 and CBLN1 may be potential therapeutic biomarkers for ovulation disorders in PCOS.

Versatile biomimetic array assembly by phase modulation of coherent acoustic waves.

A high-throughput cell-assembly method, with the advantages of adjustability, ease of operation, and good precision, is remarkable for artificial tissue engineering. Here, we present a scientific solution by introducing high rotational symmetrical coherent acoustic waves, in order to enable the shape and arrangement of the acoustic potential wells to be flexibly modulated, and therefore to assemble on a large area diverse biomimetic arrays on a microfluidic platform. Ring arrays, honeycomb, and many other biomimetic arrays are achieved by real-time modulation of the wave vectors and phase relation of acoustic beams from six directions. In the experiments, human umbilical vein endothelial cells (HUVECs), arranged in ring structures, tend to connect with the adjacent cells and reach confluency, thus directing the in vitro two-dimensional vascular network formation. Higher rotational symmetry of the six coherent acoustic waves provides much more flexibility and diversity for acoustic cell assembly. With the advantages of efficiency, diversity and adjustability, this acoustic chip is expected to fulfill many applications, such as in biochemistry, bioprinting and tissue engineering related research.

On-chip hydrogel arrays individually encapsulating acoustic formed multicellular aggregates for high throughput drug testing.

Multicellular aggregates in three-dimensional (3D) environments provide novel solid tumor models that can provide insight into in vivo drug resistance. Such models are therefore essential for developing new drugs and preventing the failure of clinical treatments. However, high-throughput cell cluster assembly and fabricating individual 3D environments that mimic the extracellular matrix (ECM) remain significant challenges. To rapidly produce mini 3D multicellular aggregate units, acoustic force assembly combined with ECM mimic hydrogel array encapsulation is developed and then integrated into a diffusion-based microfluidic device for high-throughput drug testing. The active acoustic force gathers human mononuclear leukemia cells (THP-1) into hundreds of multicellular clusters with a controllable size. Instead of continuous bulk materials, photosensitive gelatin methacryloyl (GelMA) hydrogel pillar arrays containing cell clusters at drug concentration gradients are obtained through selective area exposure. Ten azelaic acid (AZA) concentration gradient series are applied to 100 units to simultaneously test the multicellular cluster drug resistance to multiple drug conditions. Real-time green fluorescent protein (GFP) fluorescence is analyzed to monitor cell viability. The results show that cell aggregate activity is inversely related to the drug concentration in the hydrogel pillars, and shows lower sensitivity to drug toxicity than the activity of monolayer cultured cells. The 3D multicellular arrays provide numerous in vitro tumor models and can be directly used for downstream drug testing. This technology inherits the advantages of acoustic assembly, while being more flexible, practical, and high-throughput, and shows significant potential for use in further tumor related research and clinical practice.

A Portable and Accurate Phosphate Sensor Using a Gradient Fabry-Pérot Array.

Here, a portable and accurate phosphate sensor using a gradient Fabry-Pérot array (FPA) is proposed. It can form a bidirectional gradient concentration (absorbance) distribution in the gradient FPA, simplifying the complex operations to get a standard curve and saving time. The gradient FPA can effectively filter out the interference (bubbles, light intensity, and salinity) while improving the absorbance, achieving a highly accurate and stable detection. Besides, the smartphone simplifies data processing and makes sensors more portable. In this work, the detection errors of standard solutions (100, 50, and 30 µM) are 0.39, 1.48, and 1.84%, respectively, and it has also been demonstrated with errors of 2.46 (sample 1, seawater), 2.08 (sample 2, lake water), and 1.83% (sample 3, sewage) for natural samples detection, which is more accurate than a traditional analyzer. The sensor has a good performance when affected by bubbles, light intensity, and salinity. In addition, the detection time is shortened to 80 s, which is more time saving compared with traditional devices, and the limit of detection (LOD) is 0.4 µM. It can be predicted that the novel optofluidic sensor is conducive to build a smart nutrient monitoring system and will be applied in the field of biochemistry and environmental chemistry.