Machine Learning Discrimination and Ultrasensitive Detection of Fentanyl Using Gold Nanoparticle-Decorated Carbon Nanotube-Based Field-Effect Transistor Sensors.

The opioid overdose crisis is a global health challenge. Fentanyl, an exceedingly potent synthetic opioid, has emerged as a leading contributor to the surge in opioid-related overdose deaths. The surge in overdose fatalities, particularly due to illicitly manufactured fentanyl and its contamination of street drugs, emphasizes the urgency for drug-testing technologies that can quickly and accurately identify fentanyl from other drugs and quantify trace amounts of fentanyl. In this paper, gold nanoparticle (AuNP)-decorated single-walled carbon nanotube (SWCNT)-based field-effect transistors (FETs) are utilized for machine learning-assisted identification of fentanyl from codeine, hydrocodone, and morphine. The unique sensing performance of fentanyl led to use machine learning approaches for accurate identification of fentanyl. Employing linear discriminant analysis (LDA) with a leave-one-out cross-validation approach, a validation accuracy of 91.2% is achieved. Meanwhile, density functional theory (DFT) calculations reveal the factors that contributed to the enhanced sensitivity of the Au-SWCNT FET sensor toward fentanyl as well as the underlying sensing mechanism. Finally, fentanyl antibodies are introduced to the Au-SWCNT FET sensor as specific receptors, expanding the linear range of the sensor in the lower concentration range, and enabling ultrasensitive detection of fentanyl with a limit of detection at 10.8 fg mL-1.

Diagnostics of Tuberculosis with Single-Walled Carbon Nanotube-Based Field-Effect Transistors.

Tuberculosis (TB) is still threatening millions of people's lives, especially in developing countries. One of the major factors contributing to the ongoing epidemic of TB is the lack of a fast, efficient, and inexpensive diagnostic strategy. In this work, we developed a semiconducting single-walled carbon nanotube (SWCNT)-based field-effect transistor (FET) device functionalized with anti-Mycobacterium tuberculosis antigen 85B antibody (Ab85B) to detect the major M. tuberculosis-secreted antigen 85B (Ag85B). Through optimizing the device fabrication process by evaluating the mass of the antibody and the concentration of the gating electrolyte, our Ab85B-SWCNT FET devices achieved the detection of the Ag85B spiked in phosphate-buffered saline (calibration samples) with a limit of detection (LOD) of 0.05 fg/mL. This SWCNT FET biosensor also showed good sensing performance in biological matrices including artificial sputum and can identify Ag85B in serum after introducing bovine serum albumin (BSA) into the blocking layer. Furthermore, our BSA-blocked Ab85B-SWCNT FET devices can distinguish between TB-positive and -negative clinical samples, promising the application of SWCNT FET devices in point-of-care TB diagnostics. Moreover, the robustness of this SWCNT-based biosensor to the TB diagnosis in blood serum was enhanced by blocking SWCNT devices directly with a glutaraldehyde cross-linked BSA layer, enabling future applications of these SWCNT-based biosensors in clinical testing.

Dietary long-chain fatty acids promote colitis by regulating palmitoylation of STAT3 through CD36-mediated endocytosis.

The Western diet, characterized by its high content of long-chain fatty acids (LCFAs), is widely recognized as a significant triggering factor for inflammatory bowel disease (IBD). While the link between a high-fat diet and colitis has been observed, the specific effects and mechanisms remain incompletely understood. Our study provides evidence that the diet rich in LCFAs can disrupt the integrity of the intestinal barrier and exacerbate experimental colitis in mice. Mechanistically, LCFAs upregulate the signal transducer and activator of transcription-3 (STAT3) pathway in the inflammatory model, and STAT3 knockout effectively counters the pro-inflammatory effects of LCFAs on colitis. Specifically, palmitic acid (PA), a representative LCFA, enters intestinal epithelial cells via the cluster of differentiation 36 (CD36) pathway and participates in the palmitoylation cycle of STAT3. Inhibiting this cycle using pharmacological inhibitors like 2-Bromopalmitate (2-BP) and ML349, as well as DHHC7 knockdown, has the ability to alleviate inflammation induced by PA. These findings highlight the significant role of dietary LCFAs, especially PA, in the development and progression of IBD. Diet adjustments and targeted modulation offer potential therapeutic strategies for managing this condition. Model of LCFAs involvement in the palmitoylation cycle of STAT3 upon internalization into cells. Following cellular uptake through CD36, LCFAs are converted to palmitoyl-CoA. In the presence of DHHC7, palmitoyl-CoA binds to STAT3 at the C108 site, forming palmitoylated STAT3. Palmitoylation further promotes phosphorylation at the Y705 site of STAT3. Subsequently, palmitoylated STAT3 undergoes depalmitoylation by APT2 and translocates to the nucleus to exert its biological functions.

2'-Fucosyllactose restores the intestinal mucosal barrier in ulcerative colitis by inhibiting STAT3 palmitoylation and phosphorylation.

BACKGROUND & AIMS: 2'-Fucosyllactose (2'-FL), the primary constituent of human milk oligosaccharides, has been identified as a potential regulator of inflammation in inflammatory bowel disease. Despite this recognition, the specific mechanisms through which 2'-FL alleviates ulcerative colitis (UC) remain ambiguous. This study seeks to investigate the potential anti-inflammatory properties of 2'-FL concerning intestinal inflammation and uncover the associated mechanisms. METHODS: C57BL/6J mice were orally administered a daily dose of 500 mg/kg 2'-FL for 11 consecutive days, followed by the induction of colitis using 3 % (wt/vol) dextran sulfate sodium (DSS) for the final 6 days. Subsequently, a comprehensive range of techniques, including an Acyl-biotin exchange assay, fluorescein-isothiocyanate-labeled dextran assay, histopathology, ELISA, quantitative real-time PCR, Western blot, immunofluorescence staining, immunohistochemistry staining, Alcian blue-periodic acid schiff staining, TdT-mediated dUTP nick end labeling, transmission electron microscopy, iTRAQ quantitative proteomics, bioinformatics analysis, and the generation of signal transducer and activator of transcription 3 (STAT3) knockout mice, were employed to explore the relevant molecular mechanisms. RESULTS: Administration of 2'-FL significantly ameliorated DSS-induced colitis in mice and enhanced the integrity of the intestinal mucosal barrier. 2'-FL downregulated the phosphorylation of STAT3 and inhibited STAT3-related signaling pathways in colon tissues, which, in turn, reduced inflammatory responses. Interestingly, knockdown of STAT3 attenuated the protective effects of 2'-FL, highlighting that 2'-FL-mediated inflammatory attenuation is dependent on STAT3 expression. Additionally, 2'-FL could influence STAT3 activation by modulating the palmitoylation and depalmitoylation of STAT3. CONCLUSIONS: 2'-FL promotes the recovery of the intestinal mucosal barrier and suppresses inflammation in ulcerative colitis by inhibiting the palmitoylation and phosphorylation of STAT3.

Correlation Analysis Between Disease Activity and Anxiety, Depression, Sleep Disturbance, and Quality of Life in Patients with Inflammatory Bowel Disease.

Objective: To explore the correlation between disease activity and anxiety, depression, sleep quality, and quality of life in patients with inflammatory bowel disease (IBD). Methods: The disease activity of IBD patients was evaluated by 66 gastroenterologists from 42 hospitals in 22 provinces in China from September 2021 to May 2022. Anxiety, depression, sleep quality and quality of life of IBD patients were investigated and statistically analyzed by different scales, including Generalized Anxiety Disorder 7-item Scale (GAD-7), Patient Health Questionnaire-9 (PHQ-9), Pittsburgh Sleep Quality Index (PSQI), and Inflammatory Bowel Disease Quality-of-Life Questionnaire (IBD-Q). Results: A total of 2478 IBD patients were included, of which 1532 (61.8%) were in active stage and 946 (38.2%) were in remission. The proportions of active IBD with anxiety, depression, sleep disturbance, and poor quality of life were 29.5%, 29.7%, 71.1%, and 50.1%, respectively, while the proportions of remission IBD with anxiety, depression, sleep disturbance, and poor quality of life were 19.1%, 24.4%, 69.3%, and 17.4%, respectively. IBD patients who also had anxiety, depression, sleep disturbances and poor quality of life had 80 cases (8.46%) in remission and 114 cases (7.44%) in active stage, with 54 cases (9.18%) in mild activity, 51 cases (6.95%) in moderate activity and 9 cases (4.49%) in severe activity. IBD patients with different disease activity levels differed in GAD-7 scores, PHQ-9 scores, PSQI scores, and IBD-Q scores (all P<0.001). In IBD patients, anxiety, depression, and sleep disturbance, which interact with each other, can further aggravate their disease activity (all P<0.001). Conclusion: Anxiety, depression, sleep disturbances, and quality of life are strongly correlated with disease activity in IBD patients, and IBD patients with psychological disturbances are most often in the active stage and have a poor quality of life.

Bacterial Vaginosis Monitoring with Carbon Nanotube Field-Effect Transistors.

The ability to rapidly and reliably screen for bacterial vaginosis (BV) during pregnancy is of great significance for maternal health and pregnancy outcomes. In this proof-of-concept study, we demonstrated the potential of carbon nanotube field-effect transistors (NTFET) in the rapid diagnostics of BV with the sensing of BV-related factors such as pH and biogenic amines. The fabricated sensors showed good linearity to pH changes with a linear correlation coefficient of 0.99. The pH sensing performance was stable after more than one month of sensor storage. In addition, the sensor was able to classify BV-related biogenic amine-negative/positive samples with machine learning, utilizing different test strategies and algorithms, including linear discriminant analysis (LDA), support vector machine (SVM), and principal component analysis (PCA). The biogenic amine sample status could be well classified using a soft-margin SVM model with a validation accuracy of 87.5%. The accuracy could be further improved using a gold gate electrode for measurement, with accuracy higher than 90% in both LDA and SVM models. We also explored the sensing mechanisms and found that the change in NTFET off current was crucial for classification. The fabricated sensors successfully detect BV-related factors, demonstrating the competitive advantage of NTFET for point-of-care diagnostics of BV.

A Carbon Nanotube Sensor Array for the Label-Free Discrimination of Live and Dead Cells with Machine Learning.

Developing robust cell recognition strategies is important in biochemical research, but the lack of well-defined target molecules creates a bottleneck in some applications. In this paper, a carbon nanotube sensor array was constructed for the label-free discrimination of live and dead mammalian cells. Three types of carbon nanotube field-effect transistors were fabricated, and different features were extracted from the transfer characteristic curves for model training with linear discriminant analysis (LDA) and support-vector machines (SVM). Live and dead cells were accurately classified in more than 90% of samples in each sensor group using LDA as the algorithm. The recursive feature elimination with cross-validation (RFECV) method was applied to handle the overfitting and optimize the model, and cells could be successfully classified with as few as four features and a higher validation accuracy (up to 97.9%) after model optimization. The RFECV method also revealed the crucial features in the classification, indicating the participation of different sensing mechanisms in the classification. Finally, the optimized LDA model was applied for the prediction of unknown samples with an accuracy of 87.5-93.8%, indicating that live and dead cell samples could be well-recognized with the constructed model.

Knockdown of RIPK2 Inhibits Proliferation and Migration, and Induces Apoptosis via the NF-κB Signaling Pathway in Gastric Cancer.

RIPK2 is a 62 kDa protein and a member of the receptor interacting protein kinases (RIPK) family. It was previously demonstrated that RIPK2 might play a role in promoting malignant tumor progression; however, the precise function of RIPK2 in the onset and progression of gastric cancer (GC) remains unclear. In the current study, we investigated the role of RIPK2 in GC. First, we explored the expression levels of RIPK2 in multiple cancers, including GC, using a bioinformatics approach. We constructed the RIPK2-associated protein-protein interaction network using the search tool for the retrieval of interacting genes/proteins for gene ontology and Kyoto encyclopedia of genes and genomes analysis. Next, we compared the RIPK2 expression levels between GC cells and normal gastric mucosal epithelial cell (GES-1) using reverse transcription quantitative PCR analysis. We downregulated the expression of RIPK2 in GC cells to determine the effects of RIPK2 on cell growth, migration, and apoptosis. Finally, we used western blotting to investigate the RIPK2 downstream signaling pathway involved in the regulation of GC progression. Our results showed that RIPK2 was overexpressed in various tumor tissues, including GC, compared to non-cancer tissues. Moreover, RIPK2 expression was significantly upregulated in all four GC cell lines (MGC-803,SGC-7901, HGC-27 and AGS) comparing the GES-1 cells. Silencing of RIPK2 suppressed GC cell growth by inhibiting migration, and inducing apoptosis through the nuclear factor-κB (NF-κB) signaling pathway. In summary, we demonstrate that RIPK2 plays an important role in modulating GC cell proliferation, migration, and apoptosis through the NF-κB signaling pathway. Therefore, RIPK2 functions as a potential oncogene. We believe that RIPK2 can be used as a candidate biomarker, as well as a diagnostic tool, and the therapeutic target for GC.

Ubiquitin-Specific Protease 25 Aggravates Acute Pancreatitis and Acute Pancreatitis-Related Multiple Organ Injury by Destroying Tight Junctions Through Activation of The STAT3 Pathway.

Ubiquitin-specific protease 25 (USP25) plays an important role in inflammation and immunity. However, the role of USP25 in acute pancreatitis (AP) is still unclear. To evaluate the role of USP25 in AP, we conducted research on clinical AP patients, USP25wild-type(WT)/USP25 knockout (USP25-/-) mice, and pancreatic acinar cells. Our results showed that serum USP25 concentration was higher in AP patients than in healthy controls and was positively correlated with disease severity. AP patients' serum USP25 levels after treatment were significantly lower than that at the onset of AP. Moreover, USP25 expression was upregulated in cerulein-induced AP in mice, while USP25 deficiency attenuates AP and AP-related multiple organ injury. In vivo and in vitro studies showed that USP25 exacerbates AP by promoting the release of pro-inflammatory factors and destroying tight junctions of the pancreas. We showed that USP25 aggravates AP and AP-related multiple organ injury by activating the signal transducer and activator of transcription 3 (STAT3) pathway. Targeting the action of USP25 may present a potential therapeutic option for treating AP.

Personalizing prognostic prediction in early-onset Colorectal Cancer.

Accurately estimating prognosis based on clinicopathologic variables could improve risk stratification for patients with early-onset colorectal cancer (EOCRC). Our primary goal was to create and validate a survival nomogram with adequate performance for predicting overall survival (OS) in patients with EOCRC. Least absolute shrinkage and selection operator (LASSO) Cox regression analysis was applied to identify clinical features statistically related to OS. Then we established and internally validated a survival nomogram based on surveillance, epidemiology and end results (SEER) database (N=23813). A cohort of 77 patients with EOCRC from Renmin Hospital of Wuhan University (RHWU) was employed to detect the external validity of the survival nomogram. Moreover, we compared the predictive accuracy of survival nomogram with TNM stage, and also compared the OS between endoscopy and surgery groups before and after propensity score matching (PSM) among EOCRC patients with early stage (Tis-T1N0M0). We selected seven informative indexes (N stage, M stage, perineural invasion, chemotherapy, surgery primary site, summary stage and tumor grade) for the construction of the survival nomogram. Then the survival nomogram exhibited good discrimination with C-index of 0.829, 0.841 and 0.796 in the SEER training, SEER validation and RHWU validation sets, respectively. Calibration curves showed good concordance between the survival nomogram predictions and actual outcomes for 1-year, 3-year and 5-year OS. Furthermore, the survival nomogram was superior to risk stratification by TNM stage in predicting OS among patients with EOCRC. Early-stage patients treated with endoscopy showed similar survival to those with surgery before and after PSM. We proposed a survival nomogram based on the extensively used parameters to precisely predict OS in EOCRC patients. This survival nomogram will contribute to aid oncologists better risk stratification and prognostication for patients with EOCRC.

Impacts of Type 2 Diabetes on Disease Severity, Therapeutic Effect, and Mortality of Patients With COVID-19.

PURPOSE: Coronavirus disease 2019 (COVID-19) has become a topic of concern worldwide; however, the impacts of type 2 diabetes mellitus (T2DM) on disease severity, therapeutic effect, and mortality of patients with COVID-19 are unclear. METHODS: All consecutive patients with COVID-19 admitted to the Renmin Hospital of Wuhan University from January 11 to February 6, 2020, were included in this study. RESULTS: A total of 663 patients with COVID-19 were included, while 67 patients with T2DM accounted for 10.1% of the total. Compared with patients with COVID-19 without T2DM, those with T2DM were older (aged 66 years vs 57 years; P < 0.001) and had a male predominance (62.7% vs 37.3%; P = 0.019) and higher prevalence of cardiovascular diseases (61.2% vs 20.6%; P < 0.001) and urinary diseases (9% vs 2.5%; P = 0.014). Patients with T2DM were prone to developing severe (58.2% vs 46.3%; P = 0.002) and critical COVID-19 (20.9% vs 13.4%; P = 0.002) and having poor therapeutic effect (76.1% vs 60.4%; P = 0.017). But there was no obvious difference in the mortality between patients with COVID-19 with and without T2DM (4.5% vs 3.7%; P = 0.732). Multivariate logistic regression analysis identified that T2DM was associated with poor therapeutic effect in patients with COVID-19 (odd ratio [OR] 2.99; 95% confidence interval [CI], 1.07-8.66; P = 0.04). Moreover, having a severe and critical COVID-19 condition (OR 3.27; 95% CI, 1.02-9.00; P = 0.029) and decreased lymphocytes (OR 1.59; 95% CI, 1.10-2.34; P = 0.016) were independent risk factors associated with poor therapeutic effect in patients with COVID-19 with T2DM. CONCLUSIONS: T2DM influenced the disease severity and therapeutic effect and was one of the independent risk factors for poor therapeutic effect in patients with COVID-19.

Do underlying cardiovascular diseases have any impact on hospitalised patients with COVID-19?

OBJECTIVES: An outbreak of the highly contagious severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has sickened thousands of people in China. The purpose of this study was to explore the early clinical characteristics of COVID-19 patients with cardiovascular disease (CVD). METHODS: This is a retrospective analysis of patients with COVID-19 from a single centre. All patients underwent real-time reverse transcription PCR for SARS-CoV-2 on admission. Demographic and clinical factors and laboratory data were reviewed and collected to evaluate for significant associations. RESULTS: The study included 541 patients with COVID-19. A total of 144 (26.6%) patients had a history of CVD. The mortality of patients with CVD reached 22.2%, which was higher than that of the overall population of this study (9.8%). Patients with CVD were also more likely to develop liver function abnormality, elevated blood creatinine and lactic dehydrogenase (p<0.05). Symptoms of sputum production were more common in patients with CVD (p=0.026). Lymphocytes, haemoglobin and albumin below the normal range were pervasive in the CVD group (p<0.05). The proportion of critically ill patients in the CVD group (27.8%) was significantly higher than that in the non-CVD group (8.8%). Multivariable logistic regression analysis revealed that CVD (OR: 2.735 (95% CI 1.495 to 5.003), p=0.001) was associated with critical COVID-19 condition, while patients with coronary heart disease were less likely to reach recovery standards (OR: 0.331 (95% CI 0.125 to 0.880), p=0.027). CONCLUSIONS: Considering the high prevalence of CVD, a thorough CVD assessment at diagnosis and early intervention are recommended in COVID-19 patients with CVD. Patients with CVD are more vulnerable to deterioration.

Glandular orientation and shape determined by computational pathology could identify aggressive tumor for early colon carcinoma: a triple-center study.

BACKGROUND: Identifying the early-stage colon adenocarcinoma (ECA) patients who have lower risk cancer vs. the higher risk cancer could improve disease prognosis. Our study aimed to explore whether the glandular morphological features determined by computational pathology could identify high risk cancer in ECA via H&E images digitally. METHODS: 532 ECA patients retrospectively from 2 independent data centers, as well as 113 from The Cancer Genome Atlas (TCGA), were enrolled in this study. Four tissue microarrays (TMAs) were constructed across ECA hematoxylin and eosin (H&E) stained slides. 797 quantitative glandular morphometric features were extracted and 5 most prognostic features were identified using minimum redundancy maximum relevance to construct an image classifier. The image classifier was evaluated on D2/D3 = 223, D4 = 46, D5 = 113. The expression of Ki67 and serum CEA levels were scored on D3, aiming to explore the correlations between image classifier and immunohistochemistry data and serum CEA levels. The roles of clinicopathological data and ECAHBC were evaluated by univariate and multivariate analyses for prognostic value. RESULTS: The image classifier could predict ECA recurrence (accuracy of 88.1%). ECA histomorphometric-based image classifier (ECAHBC) was an independent prognostic factor for poorer disease-specific survival [DSS, (HR = 9.65, 95% CI 2.15-43.12, P = 0.003)]. Significant correlations were observed between ECAHBC-positive patients and positivity of Ki67 labeling index (Ki67Li) and serum CEA. CONCLUSION: Glandular orientation and shape could predict the high risk cancer in ECA and contribute to precision oncology. Computational pathology is emerging as a viable and objective means of identifying predictive biomarkers for cancer patients.

Decreased Serum Bilirubin Levels and Increased Uric Acid Levels are Associated with Ulcerative Colitis.

BACKGROUND In recent years, emerging evidence has suggested that ulcerative colitis occurs as a consequence of an imbalance between oxidative stress and antioxidant capacity. The objective of this study was to investigate whether serum total bilirubin and serum uric acid levels were associated with ulcerative colitis. MATERIAL AND METHODS We conducted a retrospective case-control study which included 170 patients with ulcerative colitis and 200 healthy individuals. Concentrations of serum total bilirubin and serum uric acid were obtained from biochemical information and segregated into quartiles. Logistic regression analysis was adopted to explore the correlations between levels of the 2 biochemical markers and the risk of ulcerative colitis. RESULTS Compared with healthy controls, patients with ulcerative colitis exhibited lower levels of serum bilirubin (9.30 umol/L versus 12.49 umol/L respectively, P<0.001). Multivariate logistic regression showed that the lowest quartile of total serum bilirubin was independently associated with the occurrence of ulcerative colitis (OR=2.56, 95%CI: 1.54-4.25, P<0.001). Similarly, ulcerative colitis patients exhibited higher concentrations of serum uric acid (338 umol/L versus 300 umol/L respectively, P=0.041). Multivariate logistic regression showed that the highest quartile of serum uric acid was independently associated with ulcerative colitis risk (OR=1.20, 95%CI: 1.05-1.77, P=0.045). Furthermore, a negative association was observed between serum total bilirubin and serum uric acid in patients with ulcerative colitis. CONCLUSIONS Lower levels of serum total bilirubin and higher levels of serum uric acid are associated with ulcerative colitis patients compared to healthy controls.

Ulcerative colitis with Guillain-Barré syndrome: A case report.

RATIONALE: Ulcerative colitis is a chronic and recurrent inflammatory disease involving the intestine. It is reported that about 40% of patients with ulcerative colitis have extraintestinal manifestations, where as the literature on neurological involvement as extraintestinal manifestation is rather limited. Guillain-Barré syndrome is an abnormal immune-mediated and acute-acquired demyelinating disease that mainly affects the peripheral nervous system and often has a phenomenon of protein-cell separation of cerebrospinal fluid. Here, we report a rare case of ulcerative colitis with Guillain-Barré Syndrome. PATIENT CONCERNS: We described a patient with Guillain-Barré syndrome during the remission period of ulcerative colitis. Clinical manifestations are the numbness of the upper extremities, weakness in the limbs and the inability of the fingers companion. Cerebrospinal fluid (CSF) showed albuminocytological dissociation and electromyography suggested neurogenic lesion. DIAGNOSES: Ulcerative colitis with Guillain-Barré syndrome was diagnosed based on the history of ulcerative colitis, related symptoms, typical cerebrospinal fluid albuminocytological dissociation and evidence of neurogenic injury through electromyography. INTERVENTIONS: The patient was treated with intravenous (IV) methylprednisolone. OUTCOMES: After the treatment of glucocorticoid, the symptoms of the nervous system were disappeared. LESSONS: Neurological involvement of extraintestinal manifestation during the remission period of ulcerative colitis also exists in the clinic. This case highlights the need for diagnostic vigilance in cases of ulcerative colitis involving the peripheral nerves during the remission period. We recommend cerebrospinal fluid examination and electromyography in view of rare but serious possibility of Guillain-Barré syndrome.

Upconversion nanoparticle as elemental tag for the determination of alpha-fetoprotein in human serum by inductively coupled plasma mass spectrometry.

Upconversion nanoparticles (UCNPs) have received increasing attention due to their unique optical properties. Recognizing that UCNPs are lanthanide-doped nanoparticles, we incorporated UCNPs into an immunoassay with inductively coupled plasma mass spectrometry (ICP-MS) detection for the determination of specific proteins, e.g., alpha-fetoprotein (AFP). The sensitivity of the assay was enhanced because of the ICP-MS detection of UCNPs that contained large numbers of lanthanide elemental tags. Conjugates of UCNPs and antibodies were prepared and the morphology of the conjugates was characterized by transmission electron microscopy. After a sandwich immunoreaction, the AFP was determined by the ICP-MS analysis of UCNPs. Under the optimized conditions, a limit of detection (3σ) of 0.31 ng mL-1 based on 89Y signal and 0.22 ng mL-1 based on 174Yb signal was obtained for AFP, with a dynamic range of 0.5-35 ng mL-1 and a relative standard deviation of 4.8% (c = 5 ng mL-1, n = 9). The developed method was applied to the determination of AFP in human serum and the recovery for the spiked sample was in the range of 98.6-123%. The proposed method is simple, rapid, selective and sensitive, and has a good tolerance for the complex biological matrix, indicating great potential for the application of UCNP in biological research as an elemental tag.

Application of inductively coupled plasma mass spectrometry in the study of apoptosis: determination of caspase-3 using a gold nanoparticle tag.

Apoptosis is a main type of cell death in which caspase-3 plays a key role. In this work, a simple, fast and sensitive immunoassay for caspase-3 is established by using inductively coupled plasma mass spectrometry (ICP-MS) detection and signal enhancement gold nanoparticle (Au-NP) labelling of the secondary antibody (IgG). After the immunoreaction of caspase-3, primary antibody and Au-NP labeled IgG, the concentration of caspase-3 was determined by ICP-MS analysis of the Au-NPs released from the immunocomplex. Under the optimized conditions, a limit of detection (LOD, 3σ) of 0.42 ng mL(-1) (0.31 nM) was obtained for caspase-3, with a dynamic range of 1-200 ng mL(-1) and a relative standard deviation of 4.1% (c = 5 ng mL(-1), n = 11). The proposed method has good specificity towards caspase-3. To demonstrate the application potential of the proposed method, the cell lysates of Hg(2+)-induced HepG2 cells were analyzed, and it was found that the concentration of caspase-3 increased when increasing the incubation concentration of Hg(2+). This method is easy, sensitive and selective, and has excellent capability of tolerating a complex biological matrix, indicating the potential of the ICP-MS-based assay in the study of apoptosis.