A rapid and user-friendly assay to detect the Neutrophil gelatinase-associated lipocalin (NGAL) using up-converting nanoparticles

The sequestration mechanism as a generalizable approach to improve the sensitivity of biosensors and bioassays

Biosensors and bioassays, both of which employ proteins and nucleic acids to detect specific molecular targets, have seen significant applications in both biomedical research and clinical practice. This success is largely due to the extraordinary versatility, affinity, and specificity of biomolecular recognition. Nevertheless, these receptors suffer from an inherent limitation: single, saturable binding sites exhibit a hyperbolic relationship (the "Langmuir isotherm") between target concentration and receptor occupancy, which in turn limits the sensitivity of these technologies to small variations in target concentration. To overcome this and generate more responsive biosensors and bioassays, here we have used the sequestration mechanism to improve the steepness of the input/output curves of several bioanalytical methods. As our test bed for this we employed sensors and assays against neutrophil gelatinase-associated lipocalin (NGAL), a kidney biomarker for which enhanced sensitivity will improve the monitoring of kidney injury. Specifically, by introducing sequestration we have improved the responsiveness of an electrochemical aptamer based (EAB) biosensor, and two bioassays, a paper-based "dipstick" assay and an enzyme-linked immunosorbent assay (ELISA). Doing so we have narrowed the dynamic range of these sensors and assays several-fold, thus enhancing their ability to measure small changes in target concentration. Given that introducing sequestration requires only the addition of the appropriate concentration of a high-affinity "depletant," the mechanism appears simple and easily adaptable to tuning the binding properties of the receptors employed in a wide range of biosensors and bioassays.

Lamprey immunity protein enables early detection and recurrence monitoring for bladder cancer through recognizing Neu5Gc-modified uromodulin glycoprotein in urine

The clinical management of bladder cancer (BCa) is hindered by the lack of reliable biomarkers. We aimed to investigate the potential of lamprey immunity protein (LIP), a lectin that specifically binds to multi-antennary sialylated N-glycolylneuraminic acid (Neu5Gc) structures on UMOD glycoproteins in the urine of BCa patients. Primary BCa patients had higher levels of LIP-bound Neu5Gc in urine than healthy participants and patients receiving postoperative treatment did. In addition, lectin chip assay and mass spectrometry were used to analyze the glycan chain structure, which can recognize the UMOD glycoprotein decorated with multi-antennary sialylated Neu5Gc structures. Furthermore, compared with urine samples from healthy patients (N = 2821, T/C = 0.12 ± 0.09) or benign patients (N = 360, T/C = 0.11 ± 0.08), the range of the urine T/C ratio detected using LIP test paper was 1.97 ± 0.32 in patients with bladder cancer (N = 518) with significant difference (P < 0.0001). Our results indicate that LIP may be a tool for early BCa identification, diagnosis, and monitoring. Neu5Gc-modified UMOD glycoproteins in urine and Neu5Gc-modified N-glycochains and sialyltransferases may function as potential markers in clinical trials.

Nanoparticles in the diagnosis and treatment of vascular aging and related diseases

Aging-induced alternations of vasculature structures, phenotypes, and functions are key in the occurrence and development of vascular aging-related diseases. Multiple molecular and cellular events, such as oxidative stress, mitochondrial dysfunction, vascular inflammation, cellular senescence, and epigenetic alterations are highly associated with vascular aging physiopathology. Advances in nanoparticles and nanotechnology, which can realize sensitive diagnostic modalities, efficient medical treatment, and better prognosis as well as less adverse effects on non-target tissues, provide an amazing window in the field of vascular aging and related diseases. Throughout this review, we presented current knowledge on classification of nanoparticles and the relationship between vascular aging and related diseases. Importantly, we comprehensively summarized the potential of nanoparticles-based diagnostic and therapeutic techniques in vascular aging and related diseases, including cardiovascular diseases, cerebrovascular diseases, as well as chronic kidney diseases, and discussed the advantages and limitations of their clinical applications.

Neutrophil Gelatinase-Associated Lipocalin (NGAL) in Peritoneal Dialytic Effluent: Preliminary Results on the Comparison between Two Different Methods in Patients with and without Peritonitis

Neutrophil gelatinase-associated lipocalin (NGAL) is a lipocalin involved in the immune response and is significantly high in the peritoneal dialytic effluent (PDE) of peritoneal dialysis (PD) patients with inflammation of the peritoneum membrane (peritonitis). The focus of this study was to match two different techniques for peritoneal NGAL evaluation: NGAL point-of-care test-POCT (NGAL Dipstick—NGALds) versus the laboratory-based NGAL assay and with the white cell count in PDE. In this study, we included 30 PD patients: 17 with peritonitis and 13 without. Peritoneal NGAL was tested by a turbidimetric immunoassay and by NGALds. We noticed a good positive linear correlation between the POCT results and the laboratory-based test and between the peritoneal NGALds and white cell count in PDE (both, p < 0.01). NGALds values resulted in being elevated in patients with peritonitis (300 ng/mL, IQR 300–600) in comparison to patients without (100 ng/mL, IQR 50–150) (p < 0.01). Furthermore, the NGALds test was performed in a median time of 20 mins (IQR 18–21) in comparison with the median time of 65 mins (IQR 55–69) necessary for the laboratory-based test (p < 0.01). The results of the NGALds were coherent with the laboratory-based NGAL and with the white cell count in PDE; furthermore, it was a user-friendly method with real-time findings. NGALds could be an extra tool for the diagnosis of peritonitis, helpful at the bedside of the patient, shortening the length of diagnosis, and if the laboratory-based NGAL test is not accessible.

Development of a europium nanoparticles lateral flow immunoassay for NGAL detection in urine and diagnosis of acute kidney injury

BACKGROUND

AKI is related to severe adverse outcomes and mortality with Coronavirus Disease 2019 (COVID-19) patients, that early diagnosed and intervened is imperative. Neutrophil gelatinase-associated lipocalin (NGAL) is one of the most promising biomarkers for detection of acute kidney injury (AKI), but current detection methods are inadequacy, so more rapid, convenient and accuracy methods are needed to detect NGAL for early diagnosis of AKI. Herein, we established a rapid, reliable and accuracy lateral flow immunoassay (LFIA) based on europium nanoparticles (EU-NPS) for the detection of NGAL in human urine specimens.

METHODS

A double-antibody sandwich immunofluorescent assay using europium doped nanoparticles was employed and the NGAL monoclonal antibodies (MAbs) conjugate as labels were generated by optimizing electric fusion parameters. Eighty-three urine samples were used to evaluate the clinical application efficiency of this method.

RESULTS

The quantitative detection range of NGAL in AKI was 1-3000 ng/mL, and the detection sensitization was 0.36 ng/mL. The coefficient of variation (CV) of intra-assay and inter-assay were 2.57-4.98 % and 4.11-7.83 %, respectively. Meanwhile, the correlation coefficient between europium nanoparticles-based lateral fluorescence immunoassays (EU-NPS-LFIA) and ARCHITECT analyzer was significant (R² = 0.9829, n = 83, p < 0.01).

CONCLUSIONS

Thus, a faster and easier operation quantitative assay of NGAL for AKI has been established, which is very important and meaningful to diagnose the early AKI, suggesting that the assay can provide an early warning of final outcome of disease.

Rapid and sensitive detection of NGAL for the prediction of acute kidney injury via a polydopamine nanosphere/aptamer nanocomplex coupled with DNase I-assisted recycling amplification

Early detection of acute kidney injury (AKI) is important, as early intervention and treatment can prevent further kidney injury and improve kidney health. Neutrophil gelatinase-associated lipocalin (NGAL) has emerged as the earliest and promising non-invasive biomarker of AKI in urine, and has been used as a new predictive biomarker of AKI in the bench-to-bedside journey. In this work, a nanocomplex composed of a polydopamine nanosphere (PDANS) and a fluorophore-labelled aptamer has been constructed for the detection of NGAL using a DNase I-assisted recycling amplification strategy. After the addition of NGAL, the fluorescence intensity increases linearly over the NGAL concentration range from 12.5 to 400 pg mL-1. The limit of detection of this strategy is found to be 6.25 pg mL-1, which is almost 5 times lower than that of the method that does not involve DNase I. The process can be completed within 1 h, indicating a fast fluorescence response. Furthermore, the method using the nanocomplex coupled with DNase I has been successfully utilized for the detection of NGAL in the urine from cisplatin-induced AKI and five-sixths nephrectomized mice, demonstrating its promising ability for the early prediction of AKI. This method also demonstrates the protective effect of the Huangkui capsule on AKI, and provides an effective way to screen potentially protective drugs for renal disease.

Biomarkers as point of care tests (POCT) in neonatal sepsis: A state of science review

Lack of a standard definition of neonatal sepsis and a swift diagnostic method has proven detrimental in the management of this serious condition. Biomarkers have emerged as a beacon that might help us detect neonatal sepsis more effectively. The use of point-of-care biomarkers can aid in early diagnosis and timely initiation of treatment. Procalcitonin, presepsin, interleukin-6, highly specific C-reactive protein, and neutrophil gelatinase-associated lipocalin have been proven to aid in early diagnosis and timely initiation of treatment, thereby reducing sepsis-induced morbidity and mortality. These biomarkers have been found to be useful in reducing the duration of hospital stay and monitoring the response to therapy. When used in combination with each other, or with clinical scores, they have been proven to be advantageous over the gold standard by eliminating the waiting time for blood culture results. The use of biomarkers as a point of care investigation holds a future over the traditional method. We present a state of science review of literature summarizing the current status of these biomarkers in neonatal sepsis.

Development of a novel immunoassay for the simple and fast quantitation of neutrophil gelatinase-associated lipocalin using europium(III) chelate microparticles and magnetic beads

Neutrophil gelatinase-associated lipocalin (NGAL) is a promising biomarker for diagnosing acute kidney injury (AKI). Currently, there are few assays for determining NGAL and they are complex, time-consuming or expensive. We aimed to establish an efficient immunoassay to measure NGAL in human urine simply and rapidly. A novel immunoassay for NGAL determination was established by combining a dissociation-enhanced-free time-resolved fluoroimmunoassay (TRFIA) and immunomagnetic separation. Based on a "sandwich"-type immunoassay format, analytes in samples were captured by a pair of monoclonal antibodies (mAb) in which one mAb was coated in magnetic beads and the other mAb was labeled with europium(III) chelate microparticles (CM-EUs) as "fluorescent reporters". NGAL concentrations were determined in a linear range (10-1500 ng mL^-1) with a limit of detection of 0.32 ng mL^-1. The reproducibility, recovery, and specificity of our TRFIA were acceptable. Our method was compared with that of a chemiluminescence immunoassay (CMIA) using 115 urine samples, and the results showed good correlation (R² = 0.8677). We expect our novel method to be useful for the early diagnosis of AKI.

Up-Converting Nanoparticle-Based Immunochromatographic Strip for Multi-Residue Detection of Three Organophosphorus Pesticides in Food

Organophosphorus (OP) pesticides are widely used to control pests because of their high activity. This study described a rapid and sensitive lateral flow immunochromatographic (LFIC) assay based on up-converting nanoparticles (UCNPs) for multi-residue detection of three OP pesticides. The developed assay integrated novel fluorescent material UCNPs labeled with a broad-specific monoclonal antibody. Based on the competitive platform by immobilized antigen in the test zone, the optimized UCNPs-LFIC assay enabled sensitive detection for parathion, parathion-methyl, and fenitrothion with IC50 of 3.44, 3.98, and 12.49 ng/mL (R 2 ≥ 0.9776) within 40 min. The detectable ability ranged from 0.98 to 250 ng/mL. There was no cross-reactivity with fenthion, phoxim, isocarbophos, chlorpyrifos, or triazophos, even at a high concentration of 500 ng/mL. Matrix interference from various agricultural products was also studied in food sample detection. In the spiked test, recoveries of the three OP pesticides ranged from 67 to 120% and relative standard deviations were below 19.54%. These results indicated that the proposed strip assay can be an alternative screening tool for rapid detection of the three OP pesticides in food samples.

The theoretical molecular weight of NaYF 4 :RE upconversion nanoparticles

Upconversion nanoparticles (UCNPs) are utilized extensively for biomedical imaging, sensing, and therapeutic applications, yet the molecular weight of UCNPs has not previously been reported. Herein, we present a theory based upon the crystal structure of UCNPs to estimate the molecular weight of UCNPs: enabling insight into UCNP molecular weight for the first time. We estimate the theoretical molecular weight of various UCNPs reported in the literature, predicting that spherical NaYF4 UCNPs ~ 10 nm in diameter will be ~1 MDa (i.e. 106 g/mol), whereas UCNPs ~ 45 nm in diameter will be ~100 MDa (i.e. 108 g/mol). We also predict that hexagonal crystal phase UCNPs will be of greater molecular weight than cubic crystal phase UCNPs. Additionally we find that a Gaussian UCNP diameter distribution will correspond to a lognormal UCNP molecular weight distribution. Our approach could potentially be generalised to predict the molecular weight of other arbitrary crystalline nanoparticles: as such, we provide stand-alone graphic user interfaces to calculate the molecular weight both UCNPs and arbitrary crystalline nanoparticles. We expect knowledge of UCNP molecular weight to be of wide utility in biomedical applications where reporting UCNP quantity in absolute numbers or molarity will be beneficial for inter-study comparison and repeatability.