Detection of choline and hydrogen peroxide in infant formula milk powder with near infrared upconverting luminescent nanoparticles

Sensitive detection of choline and nicotine in real samples by switching upconversion luminescence

Nicotine (3-(1-methyl-2-pyrrolidinyl)pyridine) is one of the most common addictive substances, causing the trace detection of nicotine to be very necessary. Herein, we designed and prepared a functionalized nanocomposite CS-PAA (NaYF4:19.5%Yb,0.5%Tm@NaYF4-PAA) using a simple method. The nicotine concentration was quantitatively detected through the inhibition of choline oxidase activity by nicotine and the luminescence intensity of CS-PAA being quenched by Fe3+. The mechanism of Fe3+ quenching CS-PAA emission was inferred by luminescence lifetime and UV-vis absorption spectra characterization. During the nicotine detection, both excitation (980 nm) and emission (802 nm) wavelengths of CS-PAA enable the avoidance of the interference of background fluorescence in complicated food objects, thus providing high selectivity and sensitivity with a linear range of 5-750 ng/mL and a limit of detection of 9.3 nM. The method exhibits an excellent recovery and relative standard deviation, indicating high accuracy and repeatability of the detection of nicotine.

Ratiometric luminescence detection of H2O2 in food samples using a terbium coordination polymer sensitized with 3-carboxyphenylboronic acid

A ratiometric luminescent probe was fabricated using adenosine monophosphate (AMP) as a bridging ligand and 3-carboxyphenylboronic acid (3-CPBA) as the sensitizer and functional ligand that allowed the probe to recognize hydrogen peroxide (H2O2). The probe was labeled AMP-Tb/3-CPBA. Adding H2O2 caused the nonluminescent 3-CPBA to be converted into 3-hydroxybenzoic acid, which strongly luminesces at 401 nm. This meant that adding H2O2 decreased the AMP-Tb/3-CPBA luminescence intensity at 544 nm and caused luminescence at 401 nm. The 401 and 544 nm luminescence intensity ratio (I401/I544) was strongly associated with the H2O2 concentration between 0.1 and 60.0 μM, and the detection limit was 0.23 μM. Dual emission reverse-change ratio luminescence sensing using the probe allowed environmental effects to be excluded and the assay to be very selective. We believe that the results pave the way for the development of new functionalized lanthanide coordination polymers for use in luminescence assays.

Application of Nanoparticles in Human Nutrition: A Review

Nanotechnology in human nutrition represents an innovative advance in increasing the bioavailability and efficiency of bioactive compounds. This work delves into the multifaceted dietary contributions of nanoparticles (NPs) and their utilization for improving nutrient absorption and ensuring food safety. NPs exhibit exceptional solubility, a significant surface-to-volume ratio, and diameters ranging from 1 to 100 nm, rendering them invaluable for applications such as tissue engineering and drug delivery, as well as elevating food quality. The encapsulation of vitamins, minerals, and antioxidants within NPs introduces an innovative approach to counteract nutritional instabilities and low solubility, promoting human health. Nanoencapsulation methods have included the production of nanocomposites, nanofibers, and nanoemulsions to benefit the delivery of bioactive food compounds. Nutrition-based nanotechnology and nanoceuticals are examined for their economic viability and potential to increase nutrient absorption. Although the advancement of nanotechnology in food demonstrates promising results, some limitations and concerns related to safety and regulation need to be widely discussed in future research. Thus, the potential of nanotechnology could open new paths for applications and significant advances in food, benefiting human nutrition.

Recent advances in rare earth ion-doped upconversion nanomaterials: From design to their applications in food safety analysis

The misuse of chemicals in agricultural systems and food production leads to an increase in contaminants in food, which ultimately has adverse effects on human health. This situation has prompted a demand for sophisticated detection technologies with rapid and sensitive features, as concerns over food safety and quality have grown around the globe. The rare earth ion-doped upconversion nanoparticle (UCNP)-based sensor has emerged as an innovative and promising approach for detecting and analyzing food contaminants due to its superior photophysical properties, including low autofluorescence background, deep penetration of light, low toxicity, and minimal photodamage to the biological samples. The aim of this review was to discuss an outline of the applications of UCNPs to detect contaminants in food matrices, with particular attention on the determination of heavy metals, pesticides, pathogenic bacteria, mycotoxins, and antibiotics. The review briefly discusses the mechanism of upconversion (UC) luminescence, the synthesis, modification, functionality of UCNPs, as well as the detection principles for the design of UC biosensors. Furthermore, because current UCNP research on food safety detection is still at an early stage, this review identifies several bottlenecks that must be overcome in UCNPs and discusses the future prospects for its application in the field of food analysis.

Nanoparticle applications in food - a review

The use of nanotechnology in the food industry raises uncertainty in many respects. For years, achievements of nanotechnology have been applied mainly in biomedicine and computer science, but recently it has also been used in the food industry. Due to the extremely small (nano) scale, the properties and behavior of nanomaterials may differ from their macroscopic counterparts. They can be used as biosensors to detect reagents or microorganisms, monitor bacterial growth conditions, increase food durability e.g. when placed in food packaging, reducing the amount of certain ingredients without changing the consistency of the product (research on fat substitutes is underway), improve the taste of food, make some nutrients get better absorbed by the body, etc. There are companies on the market that are already introducing nanoparticles into the economy to improve their functionality, e.g. baby feeding bottles. This review focuses on the use of nanoparticles in the food industry, both organic (chitosan, cellulose, proteins) and inorganic (silver, iron, zinc oxide, titanium oxide, etc.). The use of nanomaterials in food production requires compliance with all legal requirements regarding the safety and quantity of nano-processed food products described in this review. In the future, new methods of testing nanoparticles should be developed that would ensure the effectiveness of compounds subjected to, for example, nano-encapsulation, i.e. whether the encapsulation process had a positive impact on the specific properties of these compounds. Nanotechnology has revolutionized our approach towards food engineering (from production to processing), food storage and the creation of new materials and products, and the search for new product applications.

Choline Oxidase-Integrated Copper Metal-Organic Frameworks as Cascade Nanozymes for One-Step Colorimetric Choline Detection

Choline is an important factor for regulating human health and is widely present in various foods. In this work, a sensor strategy based on a choline oxidase-integrated copper(II) metal-organic framework with peroxidase-like activity is constructed for one-step cascade detection of choline. The one-step cascade strategy can avoid intermediate product transferring in general multi-step reactions, and the multi-enzyme activities can be well exerted under one condition, thus exhibiting excellent catalytic activity and enhanced stability. In the integrated system, choline is catalyzed by ChO_x to produce betaine and H₂O₂, which eventually got converted to hydroxyl radicals by the peroxidase nanozyme, oxidized the chromogenic substrate ABTS, and produced an observable absorption peak at 420 nm. A new choline detection method was thus established and showed a satisfactory linear relationship at 6-300 μM, which has been used for the choline analysis in milk.

Metalloporphyrin and gold nanoparticles modified hollow zeolite imidazole Framework-8 with excellent peroxidase like activity for quick colorimetric determination of choline in infant formula milk powder

Metalloporphyrin and gold nanoparticles (AuNPs) were fixed on the surface of hollow zeolite imidazole framework-8 (HZIF-8) by cation exchange and cross-linking reaction. The obtained hybrid nanozyme, Au/HZIF-8@TCPP(Fe), was fully characterized by TEM, HRTEM, EDS element mapping and XPS. Then, its peroxidase-like activity was explored with Km of 1.74 mM and Vmax of 9.60 × 10^-8 M·S^-1 towards H₂O₂, indicating excellent catalytic activity. Based on cascade reaction between choline oxidase and Au/HZIF-8@TCPP(Fe), a quick colorimetric method was established for choline detection in infant formula milk powder. After comprehensive verification, this method presented the merits of simple operation, satisfied detection limit (0.05 mM), wide linear range (0.05-2.0 mM), high accuracy (recovery of 92.2%-105.2%) and nice selectivity. This colorimetric method was applied to the determination of choline in milk powders of five brands. Our study could offer valuable reference for finding highly efficient nanozyme and constructing novel optical biosensors.

Rational design of a selective and sensitive "turn-on" fluorescent probe for monitoring and imaging hydrogen peroxide in living cells

As one type of reactive oxygen species (ROS), hydrogen peroxide (H2O2) plays a key role in regulating a variety of cellular functions. Herein, a fluorescent probe N-Py-BO was well designed and synthesized and its ability for detecting H2O2 by fluorescence intensity was evaluated. In the design, the arylboronate ester group was acted as a reaction site for H2O2. Upon reaction with H2O2 under physiological conditions, the boronate moiety in the probe was oxidized, followed by detachment from the probe and as a result, a "turn-on" fluorescence response for H2O2 was acquired. Due to the D-A structure formation between N,N'-dimethylaminobenzene and the -CN group and the linkage by thiophene and C[double bond, length as m-dash]C bonds to increase the conjugate length, this probe showed a remarkable red shift of emission wavelength (650 nm) as well as a large Stokes shift (214 nm). An excellent linear relation with concentrations of H2O2 ranging from 2.0 to 200 μM and a good selectivity over other biological species were obtained. Importantly, taking advantage of the low toxicity and good biocompatibility, the developed probe was successfully applied to monitoring and imaging H2O2 and its level fluctuation in living cells, which provided a powerful tool for evaluation of cellular oxidative stress and understanding the pathophysiological process of H2O2-related diseases.

Functional Hybrid Micro/Nanoentities Promote Agro-Food Safety Inspection

The rapid development of nanomaterials has provided a good theoretical basis and technical support to solve the problems of food safety inspection. The combination of functionalized composite nanomaterials and well-known detection methods is gradually applied to detect hazardous substances, such as chemical residues and toxins, in agricultural food products. This review concentrates on the latest agro-food safety inspection techniques and methodologies constructed with the assistance of new hybrid micro/nanoentities, such as molecular imprinting polymers integrated with quantum dots (MIPs@QDs), molecular imprinting polymers integrated with upconversion luminescent nanoparticles (MIPs@UCNPs), upconversion luminescent nanoparticles combined with metal-organic frameworks (UCNPs@MOFs), magnetic metal-organic frameworks (MOFs@Fe₃O₄), magnetic covalent-organic frameworks (Fe₃O₄@COFs), covalent-organic frameworks doped with quantum dots (COFs@QDs), nanobody-involved immunoassay for fast inspection, etc. The presented summary and discussion favor a relevant outlook for further integrating various disciplines, like material science, nanotechnology, and analytical methodology, for addressing new challenges that emerge in agro-food research fields.

Lanthanide ion (Ln3+ )-based upconversion sensor for quantification of food contaminants: A review

The food safety issue has gradually become the focus of attention in modern society. The presence of food contaminants poses a threat to human health and there are a number of interesting researches on the detection of food contaminants. Upconversion nanoparticles (UCNPs) are superior to other fluorescence materials, considering the benefits of large anti-Stokes shifts, high chemical stability, non-autofluorescence, good light penetration ability, and low toxicity. These properties render UCNPs promising candidates as luminescent labels in biodetection, which provides opportunities as a sensitive, accurate, and rapid detection method. This paper intended to review the research progress of food contaminants detection by UCNPs-based sensors. We have proposed the key criteria for UCNPs in the detection of food contaminants. Additionally, it highlighted the construction process of the UCNPs-based sensors, which includes the synthesis and modification of UCNPs, selection of the recognition elements, and consideration of the detection principle. Moreover, six kinds of food contaminants detected by UCNPs technology in the past 5 years have been summarized and discussed fairly. Last but not least, it is outlined that UCNPs have great potential to be applied in food safety detection and threw new insight into the challenges ahead.

Biosensing based on upconversion nanoparticles for food quality and safety applications

Food safety and quality regulations inevitably call for sensitive and accurate analytical methods to detect harmful contaminants in food and to ensure safe food for the consumer. Both novel and well-established biorecognition elements, together with different transduction schemes, enable the simple and rapid analysis of various food contaminants. Upconversion nanoparticles (UCNPs) are inorganic nanocrystals that convert near-infrared light into shorter wavelength emission. This unique photophysical feature, along with narrow emission bandwidths and large anti-Stokes shift, render UCNPs excellent optical labels for biosensing because they can be detected without optical background interferences from the sample matrix. In this review, we show how this exciting technique has evolved into biosensing platforms for food quality and safety monitoring and highlight recent applications in the field.

Double-enzymes-mediated fluorescent assay for sensitive determination of organophosphorus pesticides based on the quenching of upconversion nanoparticles by Fe3

Herein, a new double-enzymes-modulated fluorescent assay based on the quenching of upconversion nanoparticles (UCNPs) by Fe³⁺ was constructed for sensitive determination of OPs. OPs can inhibit the activity of acetylcholinesterase to reduce the production of choline and further lead to the lack of H₂O₂ in the presence of choline oxidase. Therefore, Fe²⁺ cannot be converted into Fe³⁺, resulting in "turn-on" fluorescence of UCNPs. Under optimal conditions, an excellent linear correlation between the inhibition efficiency and the logarithm of the chlorpyrifos concentration was achieved with a detection limit (LOD) of 6.7 ng/mL in the range of 20-2000 ng/mL. The recovery for chlorpyrifos in apples and cucumbers was 89.5-97.1%. The results were consistent with those obtained by GC-MS. Overall, the integration of UCNPs into the double-enzymes-mediated Fe³⁺/Fe²⁺ conversion endows this method with desirable rapidity, sensitivity, selectivity, stability, operational simplicity, and strong anti-interference capability, holding great potential in the application of food safety.

Sensors/nanosensors based on upconversion materials for the determination of pharmaceuticals and biomolecules: An overview

Upconversion materials have been the focus of a large body of research in analytical and clinical fields in the last two decades owing to their ability to convert light between various spectral regions and their particular photophysical features. They emit efficient and sharp ultraviolet (UV) or visible luminescence after excitation with near-infrared (NIR) light. These features overcome some of the disadvantages reported for conventional fluorescent materials and provide opportunities for high sensitivity chemo-and bio-sensing. Here, we review studies that used upconversion materials as sensors for the determination of pharmaceuticals and biomolecules in the last two decades. The articles included in this review were retrieved from the SCOPUS database using the search phrases: "upconversion nanoparticles for determination of pharmaceutical compounds", and "upconversion nanoparticles for determination of biomolecules". Details of each developed upconversion nanoparticles based sensor along with their relevant analytical parameters are reported and carefully explained.