A simple micro-batch ion-exchange resin extraction method coupled with reverse-phase HPLC (MBRE-HPLC) to quantify lactoferrin in raw and heat-treated bovine milk

Self-Responsive Fluorescence Aptasensor for Lactoferrin Determination in Dairy Products

In this study, a self-responsive fluorescence aptasensor was established for the determination of lactoferrin (Lf) in dairy products. Herein, the aptamer itself functions as both a recognition element that specifically binds to Lf and a fluorescent signal reporter in conjunction with fluorescent moiety. In the presence of Lf, the aptamer preferentially binds to Lf due to its specific and high-affinity recognition by folding into a self-assembled and three-dimensional spatial structure. Meanwhile, its reduced spatial distance in the aptamer-Lf complex induces a FRET phenomenon based on the quenching of 6-FAM by amino acids in the Lf protein, resulting in a turn-off of the fluorescence of the system. As a result, the Lf concentration can be determined straightforwardly corresponding to the change in the self-responsive fluorescence signal. Under the optimized conditions, good linearities (R2 > 0.99) were achieved in an Lf concentration range of 2~10 μg/mL for both standard solutions and the spiked matrix, as well as with the desirable detection limits of 0.68 μg/mL and 0.46 μg/mL, respectively. Moreover, the fluorescence aptasensor exhibited reliable recoveries (89.5-104.3%) in terms of detecting Lf in three commercial samples, which is comparable to the accuracy of the HPCE method. The fluorescence aptasensor offers a user-friendly, cost-efficient, and promising sensor platform for point-of-need detection.

Assessment of the Conformation Stability and Glycosylation Heterogeneity of Lactoferrin by Native Mass Spectrometry

Lactoferrin (LTF) has diverse biological activities and is widely used in functional foods and active additives. Nevertheless, evaluating the proteoform heterogeneity, conformational stability, and activity of LTF remains challenging during its production and storage processes. In this study, we describe the implementation of native mass spectrometry (nMS), glycoproteomics, and an antimicrobial activity assay to assess the quality of LTF. We systematically characterize the purity, glycosylation heterogeneity, conformation, and thermal stability of LTF samples from different sources and transient high-temperature treatments by using nMS and glycoproteomics. Meanwhile, the nMS peak intensity and antimicrobial activity of LTF samples after heat treatment decreased significantly, and the two values were positively correlated. The nMS results provide essential molecular insights into the conformational stability and glycosylation heterogeneity of different LTF samples. Our results underscore the great potential of nMS for LTF quality control and activity evaluation in industrial production.

A high-throughput differential scanning fluorimetry method for rapid detection of thermal stability and iron saturation in lactoferrin

Thermal stability and iron saturation of lactoferrin (LF) are of great significance not only for the evaluation of the biological activities of LF but also for the optimization of the isolation and drying process parameters. Differential scanning calorimetry (DSC) is a well-established and efficient method for thermal stability and iron saturation detection in LF. However, multiple DSC measurements are typically performed sequentially, thus time-consuming and low throughput. Herein, we introduced the differential scanning fluorimetry (DSF) approach to overcome such limitations. The DSF can monitor LF thermal unfolding with a commonly available real-time PCR instrument and a fluorescent dye (SYPRO orange or Glomelt), and the measured melting temperature of LF is consistent with that determined by DSC. On the basis of that, a new quantification method was established for determination of iron saturation levels using the linear correlation of the degree of ion saturation of LF with DSF measurements. Such DSF method is simple, inexpensive, rapid (<15 min), and high throughput (>96 samples per experiment), and provides a valuable alternative tool for thermal stability detection of LF and other whey proteins.

A comprehensive evaluation of milk protein molecular weight distribution based on exclusion chromatography dataset

Molecular weight is one of the main characteristic parameters of proteins, which is the basis for the functional properties of milk protein. This research aims at establishing molecular weight distribution pattern of milk protein based on exclusion chromatography. The method selected Na3PO4-Na2SO4 (0.1 M, pH 6.7) buffer as the mobile phase and detected at 220 nm by HPLC-UV. The protein molecular weight distributions were determined and compared for human milk, bovine milk, and infant formula. The proportion of macromolecular proteins is much higher in infant formula compared to human or bovine milk. The protein molecular weights of human and bovine milk are significantly different around 90, 20, 14, and 2 kDa. The results provide holistic compare of bovine milk, human milk, and infant formula through protein molecular distribution. The new evaluation indicators for protein will drive technological simulation of infant formula.

Lactoferrin in breast milk-based powders

This study aimed to determine lactoferrin (LF) in breast milk-based powders and formulas. Lactoferrin is an important whey protein in all mammalian milks and is responsible in large part for the known antimicrobial effects of human milk in particular. As breast feeding is not always possible, formulas based on cows milk have been developed in order to meet the nutritional needs of the newborn, while more recently human breast milk-based powders have been introduced to offer the biological functionality of human milk to pre-term and critically ill babies. In the present work, the amount of LF in commercial breast milk-based powders was tested by a validated RF-HPLC method for the determination of LF in breast milk in order to examine both the applicability of the method but at a second level the amount of LF in these commercial products. The detection of LF was possible but the complexity of the matrix lead us to the use the standard addition methodology in order to achieve quantification. The results indicated that breast milk-based powders had higher amount of LF than cows milk-based formulas, both non-fortified and fortified.

Synthesis of a Cation-Exchange Resin by Inverse Suspension Polymerization for Lactoferrin Extraction from Whey

Lactoferrin (LF), the main iron-binding protein of milk, has important nutritional, biological, and pharmaceutical properties. It is an essential nutritional component of newborn diets and also for adult health. Small amounts of lactoferrin can be found in whey, a nutritionally and biologically useful byproduct of the dairy industry. Although the amount of lactoferrin in whey is less than that in other sources like milk and bovine colostrum, the extraction of LF from this underused source has many economic and environmental benefits. The most common technique for the isolation of LF from dairy products is the use of cation-exchange resins. Here, we present the synthesis of a strong cation-exchange resin for the extraction of high-purity lactoferrin from whey. This resin was synthesized by inverse suspension copolymerization of aqueous solutions of sodium 2-acrylamido-2-methyl-1-propanesulfonate and N,N-methylenebisacrylamide in corn oil. The adsorption efficiency of this resin showed selective extraction of lactoferrin from four different whey sources. The adsorption efficiency of lactoferrin from these whey samples ranged from 93.8 to 97.4%.

Lactoferrin: Antimicrobial impacts, genomic guardian, therapeutic uses and clinical significance for humans and animals

Lactoferrin (LF) is a protein found in several bodily fluids, such as milk. This protein has a diverse range of functions and is evolutionarily conserved. Lactoferrin is a multifunction protein with distinct biological abilities affecting mammals' immune structures. Reports indicated that the daily uptake of LF from dairy products is unsatisfactory in detecting further health-promoting abilities. Research has shown that it protects against infection, mitigates cellular senescence, and improves nutritional quality. Additionally, LF is being studied as a potential treatment for various diseases and conditions, including gastrointestinal issues and infections. Studies have also demonstrated its effectiveness against various viruses and bacteria. In this article, we'll look closer at the structure of LF and its various biological activities, including its antimicrobial, anti-viral, anti-cancer, anti-osteoporotic, detoxifying, and immunomodulatory properties. More specifically, the protective effect of LF against oxidative DNA damage was also clarified through its ability to abolish DNA damaging issues without interfacing with host genetic material. Fortification with LF protects mitochondria dysfunction syndromes via sustaining redox status and biogenesis and suppressing apoptosis and autophagy singling. Additionally, we'll examine the potential benefits of lactoferrin and provide an overview of recent clinical trials conducted to examine its use in laboratory and living models.

Study of SI-traceable purity assessment of bovine lactoferrin using mass balance approach and amino acid-based isotope dilution liquid chromatography-mass spectrometry

The accurate measurement of bovine lactoferrin (bLF) attracts wide attention in food and nutraceutical applications as its important physiological and nutritional functions. We present SI traceable procedures for assessing bLF purity using mass balance method and amino acid (AA)-based isotope dilution mass spectrometry (IDMS). The mass balance method was revealed with a purity of 0.938 ± 0.011 g/g by deducting all aspects of impurities, including related structure impurities of 4.60%, ignition residue of 0.28%, Cl^- of 1.10%, SO₄^2- of 0.13%, and moisture of 0.17%. The AA-based IDMS quantitative result was 0.937 ± 0.027 g/g. Hydrolysis conditions were optimized and methodology validation including, accuracy, precision, were studied. Good consistency was achieved between the two independent strategies and bLF purity assigned via the weighted mean value of their results was 0.938 ± 0.015 g/g. These analyses are expected to be applicable to proteins quantification and development of LF certified reference materials.

An Efficient Heparin Affinity Column Purification Method Coupled with Ultraperformance Liquid Chromatography for the Quantification of Native Lactoferrin in Breast Milk

Lactoferrin (LF) is a bioactive multifunctional protein and found in the highest amounts in human milk. Several methods can be used to quantify LF. However, quantification of native LF has garnered relatively little interest to date. This study aimed to develop a novel efficient two-step method for quantifying native LF in breast milk. During the analysis, LF was first extracted with phosphate buffer (pH 5.0), purified using a heparin affinity column. Subsequently, LF was detected using ultraperformance liquid chromatography (UPLC) at a wavelength of 201 nm. A linear calibration curve was obtained in the range of 5–200 mg/L. The limit of detection and limit of quantitation were 1 mg/L and 5 mg/L, respectively, indicating that the validated method could be employed to quantify LF in breast milk. Compared with previous HPLC methods, this method demonstrated several remarkable advantages, including simple operation, low-cost detection, and high accuracy. Hence, the results demonstrate an efficient method that can be employed commercially to purify and analyze LF in human milk samples.

Lactoferrin and Its Detection Methods: A Review

Lactoferrin (LF) is one of the major functional proteins in maintaining human health due to its antioxidant, antibacterial, antiviral, and anti-inflammatory activities. Abnormal levels of LF in the human body are related to some serious diseases, such as inflammatory bowel disease, Alzheimer’s disease and dry eye disease. Recent studies indicate that LF can be used as a biomarker for diagnosis of these diseases. Many methods have been developed to detect the level of LF. In this review, the biofunctions of LF and its potential to work as a biomarker are introduced. In addition, the current methods of detecting lactoferrin have been presented and discussed. We hope that this review will inspire efforts in the development of new sensing systems for LF detection.

Stability-Indicating Analytical Approach for Stability Evaluation of Lactoferrin

Lactoferrin is a multifunctional iron-binding glycoprotein in milk. Due to its potential for the treatment of various diseases, interest in products containing lactoferrin is increasing. However, as a protein, it is prone to degradation, which critically affects the quality of products. Therefore, the main purpose of our work was to develop a stability-indicating analytical approach for stability evaluation of lactoferrin. We were focused on two complementary methods: reversed-phase and size-exclusion chromatography. The stability-indicating nature of the selected methods was confirmed. They were successfully validated by following the ICH guidelines and applied to preliminary lactoferrin stability studies. Up to three degradation products, as well as aggregates and fragments of lactoferrin, were detected in various samples using complementary reversed-phase and size-exclusion chromatographic methods. The analytical approach was additionally extended with three spectroscopic techniques (absorbance, intrinsic fluorescence, and bicinchoninic acid method), which may provide valuable complementary information in some cases. The presented analytical approach allows the stability evaluation of lactoferrin in various samples, including the ability to detect differences in its degradation mechanisms. Furthermore, it has the potential to be used for the quality control of products containing lactoferrin.

Sensitive immunoassays based on specific monoclonal IgG for determination of bovine lactoferrin in cow milk samples

Lactoferrin (LF), a bioactive multifunctional protein of the transferrin family, is found mainly in the secretions of all mammals, especially in milk. In the present study, a hybridoma cell (LF8) secreting IgG against bovine LF was screened, and the purified LF8 mAb showed high specificity and affinity to bovine LF. The linear range of ic-ELISA to detect LF was 9.76 ~ 625 ng/mL, with a limit of detection (LOD) of 0.01 ng/mL. The average recovery of intra- and inter-assay were (104.45 ± 4.12)% and (107.13 ± 4.72)%, respectively. The LOD of colloidal gold- and AuNFs-based strip by naked eye were 9.7 and 2.4 ng/mL, respectively, and the detection time was less than 10 min without any samples pretreatment and expensive equipment. The developed ELISA and lateral flow immunosensors based on specific IgG could be used directly for rapid detection of the bovine LF content in cow milk samples.

Bovine Lactoferrin Quantification in Dairy Products by a Simple Immunoaffinity Magnetic Purification Method Coupled with High-Performance Liquid Chromatography with Fluorescence Detection

This study described a simple, specific, and sensitive method using immunoaffinity magnetic purification coupled with high-performance liquid chromatography-fluorescence (HPLC-FL) detection for determination of bovine lactoferrin (bLf) in dairy products. BLf was selectively extracted from dairy products using immunoaffinity beads and then detected by HPLC-FL with its intrinsic fluorescence. During the analysis, standard solutions of bLf were pretreated with Tween 20, an anti-adsorptive agent, for blocking the nonspecific binding of bLf to polypropylene tubes. The calibration curve was linear over the range of 0.8-30 μg mL^-1. The validated method was successfully applied to measure bLf at the intact level in dairy products.

A rapid HPLC method for the determination of lactoferrin in milk of various species

This Research Communication describes the adaptation and testing of an RP-HPLC method, previously tested for the determination of lactoferrin (LF) in whey, for its applicability to determine milk lactoferrin content. Milk samples of various species, namely, ovine, caprine, bovine, donkey and human milk, were tested. The advantage of this RP-HPLC method includes speed and convenience, as it does not include extensive pretreatment or separation steps. A simple pre-treatment step was added in order to remove fat and proteins of the casein family and the samples were tested. The results varied in terms of elution of the LF peak both between the milk of the different species as well as from the initial application on whey. The peak resolution was satisfactory in the cases of ovine, bovine and donkey milk samples while for caprine and human milk an interference with other peaks was observed. Nevertheless, quantification of LF was found possible for all samples. This new application of the modified method will allow the determination of LF in milk samples of the tested species either for everyday analysis or as a useful qualitative screening for presence or absence of LF.