Multifunctional Magnetic Particles for Combined Circulating Tumor Cells Isolation and Cellular Metabolism Detection

Research progress on the multi-omics and survival status of circulating tumor cells

In the dynamic process of metastasis, circulating tumor cells (CTCs) emanate from the primary solid tumor and subsequently acquire the capacity to disengage from the basement membrane, facilitating their infiltration into the vascular system via the interstitial tissue. Given the pivotal role of CTCs in the intricate hematogenous metastasis, they have emerged as an essential resource for a deeper comprehension of cancer metastasis while also serving as a cornerstone for the development of new indicators for early cancer screening and new therapeutic targets. In the epoch of precision medicine, as CTC enrichment and separation technologies continually advance and reach full fruition, the domain of CTC research has transcended the mere straightforward detection and quantification. The rapid advancement of CTC analysis platforms has presented a compelling opportunity for in-depth exploration of CTCs within the bloodstream. Here, we provide an overview of the current status and research significance of multi-omics studies on CTCs, including genomics, transcriptomics, proteomics, and metabolomics. These studies have contributed to uncovering the unique heterogeneity of CTCs and identifying potential metastatic targets as well as specific recognition sites. We also review the impact of various states of CTCs in the bloodstream on their metastatic potential, such as clustered CTCs, interactions with other blood components, and the phenotypic states of CTCs after undergoing epithelial-mesenchymal transition (EMT). Within this context, we also discuss the therapeutic implications and potential of CTCs.

Organic metal chalcogenide-assisted metabolic molecular diagnosis of central precocious puberty

Metabolic analysis in biofluids based on laser desorption/ionization mass spectrometry (LDI-MS), featuring rapidity, simplicity, small sample volume and high throughput, is expected to be a powerful diagnostic tool. Nevertheless, the signals of most metabolic biomarkers obtained by matrix-assisted LDI-MS are too limited to achieve a highly accurate diagnosis due to serious background interference. To address this issue, nanomaterials have been frequently adopted in LDI-MS as substrates. However, the "trial and error" approach still dominates the development of new substrates. Therefore, rational design of novel LDI-MS substrates showing high desorption/ionization efficiency and no background interference is extremely desired. Herein, four few-layered organic metal chalcogenides (OMCs) were precisely designed and for the first time investigated as substrates in LDI-MS, which allowed a favorable internal energy and charge transfer by changing the functional groups of organic ligands and metal nodes. As a result, the optimized OMC-assisted platform satisfyingly enhanced the mass signal by ≈10 000 fold in detecting typical metabolites and successfully detected different saccharides. In addition, a high accuracy diagnosis of central precocious puberty (CPP) with potential biomarkers of 12 metabolites was realized. This work is not only expected to provide a universal detection tool for large-scale clinical diagnosis, but also provides an idea for the design and selection of LDI-MS substrates.

Diagnosis of Parkinson's Disease via the Metabolic Fingerprint in Saliva by Deep Learning

Parkinson's disease (PD) is the second cause of the neurodegenerative disorder, affecting over 6 million people worldwide. The World Health Organization estimated that population aging will cause global PD prevalence to double in the coming 30 years. Optimal management of PD shall start at diagnosis and requires both a timely and accurate method. Conventional PD diagnosis needs observations and clinical signs assessment, which are time-consuming and low-throughput. A lack of body fluid diagnostic biomarkers for PD has been a significant challenge, although substantial progress has been made in genetic and imaging marker development. Herein, a platform that noninvasively collects saliva metabolic fingerprinting (SMF) by nanoparticle-enhanced laser desorption-ionization mass spectrometry with high-reproducibility and high-throughput, using ultra-small sample volume (down to 10 nL), is developed. Further, excellent diagnostic performance is achieved with an area-under-the-curve of 0.8496 (95% CI: 0.7393-0.8625) by constructing deep learning model from 312 participants. In conclusion, an alternative solution is provided for the molecular diagnostics of PD with SMF and metabolic biomarker screening for therapeutic intervention.

A nitrogen-doped graphene tube composite based on immobilized metal affinity chromatography for the capture of phosphopeptides

A novel immobilized metal affinity chromatography (IMAC) functional composite, mNi@N-GrT@PDA@Ti⁴⁺, was fabricated based on ultrathin magnetic nitrogen-doped graphene tube (mNi@N-GrT) after chelated Ti⁴⁺ with polydopamine, following as a magnetic solid-phase extraction sorbent for rapidly selective enrichment and mass spectrometry identification of phosphorylated peptides. After optimized, the composite exhibited high specificity in the enrichment of phosphopeptides from the digest mixture of β-casein and bovine serum albumin (BSA). The robust method presented the low detection limits (1 fmol, 200 μL) and excellent selectivity (1:100) in the molar ration mixture of β-casein and BSA digests. Furthermore, the selective enrichment of phosphopeptides in the complex bio-samples, was successfully carried out. The results showed that 28 phosphopeptides were finally detected in mouse brain, and 2087 phosphorylated peptides were identified in the HeLa cells extracts with specific selectivity of 95.6%. The enrichment performance of mNi@N-GrT@PDA@Ti⁴⁺ was satisfactory, suggesting that the functional composite provided a potential application in the enrichment of trace phosphorylated peptides from the complex biological matrix.

Metal-mediated Fe3O4@polydopamine-aptamer capture nanoprobe coupling multifunctional MXene@Au@Pt nanozyme for direct and portable photothermal analysis of circulating breast cancer cells

Breast cancer (BC) is the most common cancer in the world and circulating tumor cells (CTCs) are reliable biomarkers for early breast cancer diagnosis in a non-invasive manner. However, effective isolation and sensitive detection of BC-CTCs by portable devices in human blood samples are extremely challenging. Herein, we proposed a highly sensitive and portable photothermal cytosensor for direct capture and quantification of BC-CTCs. To achieve efficient isolation of BC-CTCs, aptamer functionalized Fe₃O₄@PDA nanoprobe was facilely prepared through Ca²⁺-mediated DNA adsorption. To further detect the captured BC-CTCs with high sensitivity, multifunctional two-dimensional Ti₃C₂@Au@Pt nanozyme was synthesized, which not only possessed superior photothermal effect but also exhibited high peroxidase-like activity for catalyzing 3,3',5,5'-tetramethylbenzidine (TMB) to produce TMB oxide (oxTMB) with a strong photothermal characteristic, combining with Ti₃C₂@Au@Pt to synergistically amplify the temperature signal. Moreover, numerous Ti₃C₂@Au@Pt nanocomposites would be selectively attained on the BC-CTCs surface through multi-aptamer recognition and binding strategy, which further enhanced the specificity and facilitated signal amplification. Therefore, direct separation and highly sensitive detection of BC-CTCs was successfully achieved in human blood samples. More significantly, the controlled release of the captured BC-CTCs without affecting cell viability could be straightforwardly realized by a simple strand displacement reaction. Thus, with the distinct features of portability, high sensitivity, and easy operation, the current method holds great promise for early diagnosis of breast cancer.

Deep Learning of Dual Plasma Fingerprints for High-Performance Infection Classification

Infection classification is the key for choosing the proper treatment plans. Early determination of the causative agents is critical for disease control. Host responses analysis can detect variform and sensitive host inflammatory responses to ascertain the presence and type of the infection. However, traditional host-derived inflammatory indicators are insufficient for clinical infection classification. Fingerprints-based omic analysis has attracted increasing attention globally for analyzing the complex host systemic immune response. A single type of fingerprints is not applicable for infection classification (area under curve (AUC) of 0.550-0.617). Herein, an infection classification platform based on deep learning of dual plasma fingerprints (DPFs-DL) is developed. The DPFs with high reproducibility (coefficient of variation <15%) are obtained at low sample consumption (550 nL native plasma) using inorganic nanoparticle and organic matrix assisted laser desorption/ionization mass spectrometry. A classifier (DPFs-DL) for viral versus bacterial infection discrimination (AUC of 0.775) and coronavirus disease 2019 (COVID-2019) diagnosis (AUC of 0.917) is also built. Furthermore, a metabolic biomarker panel of two differentially regulated metabolites, which may serve as potential biomarkers for COVID-19 management (AUC of 0.677-0.883), is constructed. This study will contribute to the development of precision clinical care for infectious diseases.

Construction of a ternary component chip with enhanced desorption efficiency for laser desorption/ionization mass spectrometry based metabolic fingerprinting

Introduction: In vitro metabolic fingerprinting encodes diverse diseases for clinical practice, while tedious sample pretreatment in bio-samples has largely hindered its universal application. Designed materials are highly demanded to construct diagnostic tools for high-throughput metabolic information extraction. Results: Herein, a ternary component chip composed of mesoporous silica substrate, plasmonic matrix, and perfluoroalkyl initiator is constructed for direct metabolic fingerprinting of biofluids by laser desorption/ionization mass spectrometry. Method: The performance of the designed chip is optimized in terms of silica pore size, gold sputtering time, and initiator loading parameter. The optimized chip can be coupled with microarrays to realize fast, high-throughput (∼second/sample), and microscaled (∼1 μL) sample analysis in human urine without any enrichment or purification. On-chip urine fingerprints further allow for differentiation between kidney stone patients and healthy controls. Discussion: Given the fast, high throughput, and easy operation, our approach brings a new dimension to designing nano-material-based chips for high-performance metabolic analysis and large-scale diagnostic use.

Cell membrane-coated nanoparticles for the treatment of bacterial infection

Despite the enormous success of antibiotics in antimicrobial therapy, the rapid emergence of antibiotic resistance and the complexity of the bacterial infection microenvironment make traditional antibiotic therapy face critical challenges against resistant bacteria, antitoxin, and intracellular infections. Consequently, there is a critical need to design antimicrobial agents that target infection microenvironment and alleviate antibiotic resistance. Cell membrane-coated nanoparticles (CMCNPs) are biomimetic materials that can be obtained by wrapping the cell membrane vesicles directly onto the surface of the nanoparticles (NPs) through physical means. Incorporating the biological functions of cell membrane vesicles and the superior physicochemical properties of NPs, CMCNPs have shown great promise in recent years for targeting infections, neutralizing bacterial toxins, and designing bacterial infection vaccines. This review highlights topics where CMCNPs present great value in advancing the treatment of bacterial infections, including drug delivery, detoxification, and vaccination. Lastly, we discuss the future hurdles and prospects of translating this technique into clinical practice, providing a comprehensive review of the technological developments of CMCNPs in the treatment of bacterial infections. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Infectious Disease Therapeutic Approaches and Drug Discovery > Emerging Technologies Nanotechnology Approaches to Biology > Nanoscale Systems in Biology.

Metabolic Molecular Diagnosis of Inflammatory Bowel Disease by Synergistical Promotion of Layered Titania Nanosheets with Graphitized Carbon

Due to inefficient diagnostic methods, inflammatory bowel disease (IBD) normally progresses into severe complications including cancer. Highly efficient extraction and identification of metabolic fingerprints are of significance for disease surveillance. In this work, we synthesized a layered titania nanosheet doped with graphitized carbon (2D-GC-mTNS) through a simple one-step assembly process for assisting laser desorption ionization mass spectrometry (LDI-MS) for metabolite analysis. Based on the synergistic effect of graphitized carbon and mesoporous titania, 2D-GC-mTNS exhibits good extraction ability including high sensitivity (< 1 fmol µL^-1) and great repeatability toward metabolites. A total of 996 fingerprint spectra were collected from hundreds of native urine samples (including IBD patients and healthy controls), each of which contained 1220 m/z metabolite features. Diagnostic model was further established for precise discrimination of patients from healthy controls, with high area under the curve value of 0.972 and 0.981 toward discovery cohort and validation cohort, respectively. The 2D-GC-mTNS promotes LDI-MS to be close to clinical application, with rapid speed, minimum sample consumption and free of sample pretreatment.

Supplementary Information

The online version contains supplementary material available at 10.1007/s43657-022-00055-0.

One-Chip Isolation of Drug-Resistant Acute Myeloid Leukemia Cells with CXCR4-Targeted Magnetic Fluorescent Nanoprobes

Drug resistance and relapse lead to high mortality in acute myeloid leukemia, and studies have shown that CXCR4 overexpression is highly correlated with poor prognosis and drug resistance in leukemia cells. Isolation and detection of AML cells with CXCR4 overexpression will be crucial to the treatment of AML. In this paper, magnetic nanoparticles were firstly prepared successfully by high-temperature thermal decomposition method, and then characterized by TEM, VSM and DLS. Subsequently CXCR4-targeted magnetic fluorescent nanoprobes conjugated with antibody 12G5 were constructed by stepwise coupling. In cell experiments, the obtained probes demonstrated excellent targeting efficacy to CXCR4 overexpressed AML cells HL-60. In addition, HL-60 cells labelled with the magnetic probes can be magnetic isolated successfully in one microfluidics chip, with efficiency of 82.92 ± 7.03%. Overall, this method utilizes the superiority of superparamagnetic nanomaterials and microfluidic technology to achieve the enrichment and capture of drug-resistant cells in a microfluidic chip, providing a new idea for the isolation and detective of drug-resistant acute myeloid leukemia cells.

Inorganic Matrices Assisted Laser Desorption/Ionization Mass Spectrometry for Metabolic Analysis in Bio-fluids

Metabolic analysis in bio-fluids interprets the end products in the bio-process, emerging as an irreplaceable disease diagnosis and monitoring platform. Laser desorption/ionization mass spectrometry (LDI MS) based metabolic analysis exhibits great potential for clinical applications in terms of high throughput, rapid signal readout, and minimal sample preparation. There are two essential elements to construct the LDI MS-based metabolic analysis: 1) well-designed nanomaterials as matrices; 2) machine learning algorithms for data analysis. This review highlights the development of various inorganic matrices to comprehend the advantages of LDI MS in metabolite detection and the recent diagnostic applications based on target metabolite detection and untargeted metabolic fingerprints in biological fluids.

Monolithic Gold Nanoparticles/Thiol-β-cyclodextrin-Functionalized TiO2 Nanowires for Enhanced SALDI MS Detection and Imaging of Natural Products

Surface-assisted laser desorption/ionization mass spectrometry (SALDI MS) has been successfully applied in the analysis of various small molecules. In this work, gold nanoparticles/thiol-β-cyclodextrin-functionalized TiO₂ nanowires (AuNPs/SH-β-CD-TiO₂ NWs) were prepared to enhance the performance of SALDI MS and mass spectrometry imaging (MSI). A monolithic TiO₂ film was first grown on an indium tin oxide (ITO) glass slide via a modified sol-gel method and treated in an alkaline environment to form nanowires. TiO₂ NWs were chemically modified by SH-β-CD for immobilizing AuNPs densely and strongly. Compared with the conventional organic matrix 2,5-dihydroxybenzoic acid (DHB), the prepared AuNPs/SH-β-CD-TiO₂ NWs showed superior performances on detection sensitivity, repeatability, and analyte coverage. Analytes typically detectable with negative-ion matrix-assisted laser desorption/ionization (MALDI) MS could also be observed using AuNPs/SH-β-CD-TiO₂ NWs in the positive ion mode. Its successful usage efficiently enhanced the SALDI MS detection of various small molecules such as carbohydrates, fatty acids, and bile acids in the positive ion mode. The developed SALDI substrate was further used to characterize and discriminate the natural and in vitro cultured Calculus Bovis, as well as natural and artificial Moschus. Furthermore, the spatial distribution of several natural products in spearmint leaves and potato tubers was explored by tissue imprinting and deposition on the AuNPs/SH-β-CD-TiO₂ NW surface for SALDI MSI in dual-polarity mode, respectively. The wide application and satisfied detection sensitivity make AuNPs/SH-β-CD-TiO₂ NWs ideal for SALDI MS and MSI of various natural products.

Nanostructured Substrates as Matrices for Surface Assisted Laser Desorption/Ionization Mass Spectrometry: A Progress Report from Material Research to Biomedical Applications

Within the past two decades, the escalation of research output in nanotechnology fields has boosted the development of novel nanoparticles and nanostructured substrates for use as matrices in surface assisted laser desorption/ionization mass spectrometry (SALDI-MS). The application of nanomaterials as matrices, rather than organic matrices, offers remarkable characteristics that allow the analysis of small molecules with fewer matrix interfering peaks, and share higher detection sensitivity, specificity, and reproducibility. The technological advancement of SALDI-MS has in turn, propelled the application of the analytical technique in the field of biomedical analysis. In this review, the properties and fabrication methods of nanostructured substrates in SALDI-MS such as metallic-, carbon-, and silicon-based nanostructures, quantum dots, metal-organic frameworks, and covalent-organic frameworks are described. Additionally, the latest progress (most within 5 years) of biomedical applications in small molecule, large biomolecule, and MS imaging analysis including metabolite profiling, drug monitoring, bacteria identification, disease diagnosis, and therapeutic evaluation are demonstrated. Key parameters that govern nanomaterial's SALDI efficiency in biomolecule analysis are also discussed. Finally, perspectives of the future development are given to provide a better advancement and promote practical application in clinical MS.

Porous Inorganic Materials for Bioanalysis and Diagnostic Applications

Porous inorganic materials play an important role in adsorbing targeted analytes and supporting efficient reactions in analytical science. The detection performance relies on the structural properties of porous materials, considering the tunable pore size, shape, connectivity, etc. Herein, we first clarify the enhancement mechanisms of porous materials for bioanalysis, concerning the detection sensitivity and selectivity. The diagnostic applications of porous material-assisted platforms by coupling with various analytical techniques, including electrochemical sensing, optical spectrometry, and mass spectrometry, etc., are then reviewed. We foresee that advanced porous materials will bring far-reaching implications in bioanalysis toward real-case applications, especially as diagnostic assays in clinical settings.

Dual-modality loop-mediated isothermal amplification for pretreatment-free detection of Septin9 methylated DNA in colorectal cancer

Currently, the determination of DNA methylation is still a challenge due to the limited efficiency of enrichment, bisulfite modification, and detection. In this study, a dual-modality loop-mediated isothermal amplification integrated with magnetic bead isolation is  proposed for the determination of methylated Septin9 gene in colorectal cancer. Magnetic beads modified with anti-methyl cytosine antibody were prepared for fast enrichment of methylated DNA through specific immunoaffinity (30 min). One-pot real-time fluorescence and colorimetric loop-mediated isothermal amplification were simultaneously developed for detecting methylated Septin9 gene (60 min). The real-time fluorescence generating by SYTO-9 dye (excitation: 470 nm and emission: 525 nm) and pH indicator (neutral red) was used for quantitative and visualized detection of methylated DNA. This method was demonstrated to detect methylated DNA from HCT 116 cells ranging from 2 to 0.02 ng/μL with a limit of detection of 0.02 ± 0.002 ng/μL (RSD: 9.75%). This method also could discriminate methylated Septin9 in 0.1% HCT 116 cells (RSD: 6.60%), suggesting its high specificity and sensitivity. The feasibility of this assay was further evaluated by clinical plasma samples from 20 colorectal cancer patients and 20 healthy controls, which shows the potential application in simple, low cost, quantitative, and visualized detection of methylated nucleic acids.

Material-assisted mass spectrometric analysis of low molecular weight compounds for biomedical applications

Low molecular weight compounds play an important role in encoding the current physiological state of an individual. Laser desorption/ionization mass spectrometry (LDI MS) offers high sensitivity with low cost for molecular detection, but it is not able to cover small molecules due to the drawbacks of the conventional matrix. Advanced materials are better alternatives, showing little background interference and high LDI efficiency. Herein, we first classify the current materials with a summary of compositions and structures. Matrix preparation protocols are then reviewed, to enhance the selectivity and reproducibility of MS data better. Finally, we highlight the biomedical applications of material-assisted LDI MS, at the tissue, bio-fluid, and cellular levels. We foresee that the advanced materials will bring far-reaching implications in LDI MS towards real-case applications, especially in clinical settings.

Highly Integrated Cell-Imprinted Biomimetic Interface for All-in-One Diagnosis of Heterogeneous Circulating Tumor Cells

Single-cell capture and in situ analysis of circulating tumor cells (CTCs) in blood are of great significance for early cancer diagnosis, prognosis, and individualized treatment. However, designing an all-in-one platform that enables not only efficiently specific isolation of CTCs but also in situ analysis of heterogeneity and drug screening is challenging. Here, a cell-imprinted alginate hydrogel (CIAH) interface with all-in-one functions was developed for the capture, in situ analysis, and drug-response study at a single-cell level. Based on the equivalent morphology and "specific odor" left by template cells and supplemented by natural antibody, the CIAH interface exhibited outstanding performance in isolating CTCs from samples suffering from cancers. Beyond capture, the CIAH interface was also able to serve as a high-throughput platform for subpopulation analysis and drug response of heterogeneous CTCs. We demonstrated that the highly integrated multifunctional CIAH interface is a promising new tool for single-cell profiling of phenotypic heterogeneity and guiding of personalized anticancer therapy.

Immunoengineered magnetic-quantum dot nanobead system for the isolation and detection of circulating tumor cells

Background

Highly efficient capture and detection of circulating tumor cells (CTCs) remain elusive mainly because of their extremely low concentration in patients’ peripheral blood.

Methods

We present an approach for the simultaneous capturing, isolation, and detection of CTCs using an immuno-fluorescent magnetic nanobead system (iFMNS) coated with a monoclonal anti-EpCAM antibody.

Results

The developed antibody nanobead system allows magnetic isolation and fluorescent-based quantification of CTCs. The expression of EpCAM on the surface of captured CTCs could be directly visualized without additional immune-fluorescent labeling. Our approach is shown to result in a 70–95% capture efficiency of CTCs, and 95% of the captured cells remain viable. Using our approach, the isolated cells could be directly used for culture, reverse transcription-polymerase chain reaction (RT-PCR), and immunocytochemistry (ICC) identification. We applied iFMNS for testing CTCs in peripheral blood samples from a lung cancer patient.

Conclusions

It is suggested that our iFMNS approach would be a promising tool for CTCs enrichment and detection in one step.

Graphic abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-021-00860-1.

The isolation and analysis of fetal nucleated red blood cells using multifunctional microbeads with a nanostructured coating toward early noninvasive prenatal diagnostics

Prenatal diagnostics holds great significance for pregnant women desiring healthy babies. Fetal nucleated red blood cells (fNRBCs), bearing the complete genome of the fetus, have been regarded as an important biomarker for noninvasive prenatal diagnostics (NIPD). The high-performance detection and enrichment of fNRBCs from maternal blood, especially during early pregnancy, is urgently needed for NIPD, which, unfortunately, remains a big challenge for early-pregnancy fNRBC isolation. In this study, we developed an innovative platform based on silica microbeads for fNRBC isolation and release in early pregnancy. Microbeads were coated with self-assembled MnO₂ nanoparticles (SiO₂@MnO₂) and then modified with a specific antibody. Benefiting from the three-dimensional nanostructure of the MnO₂ nanoparticles, the isolation efficiency of the fNRBCs was enhanced. Subsequently, fNRBCs were released via dissolving the MnO₂-nanoparticle coating using oxalic acid. We successfully isolated fNRBCs from the maternal peripheral blood samples of 20 pregnant women in the early pregnancy period, ranging from 41 to 62 gestational days. More importantly, the fetal origin of isolated cells was confirmed via fluorescent in situ hybridization and short tandem repeat analysis. This platform based on SiO₂@MnO₂ microbeads has verified the existence of fNRBCs in early-pregnancy maternal blood and is a promising approach for NIPD in early pregnancy.

Lab in a tube: Isolation, extraction, and isothermal amplification detection of exosomal long noncoding RNA of gastric cancer

Tumor-derived exosomes that inherit molecular information on parental cells hold great promise for cancer diagnostics. Currently, two main technical challenges, time-consuming and labor-intensive isolation of exosome and nucleic acid extraction with limited recovery that have restricted the detection of ultralow abundance exosomal nucleic acids. Here, we proposed a simple, efficient and "lab in a tube" system for the detection of exosomal nucleic acids, which fully integrated exosomes enrichment using immunomagnetic beads (IMB) (10 min), fast exosomes lysis based on NP-40 lysate (5 min) and sensitive loop-mediated isothermal amplification (LAMP) in a tube. This method was demonstrated by detecting two exosomal long noncoding RNA biomarkers of gastric cancer (HOTTIP and lncRNA-GC1) with a dynamic detection ranging from 300 ng/μL to 10 ng/μL, and the detection limit of LAMP was 10 ng/μL. Additionally, this platform exhibited good performance in the analysis of exosomal HOTTIP RNA directly in human serum samples, which has the potential for detection of low-abundance exosomal nucleic acid biomarkers from cancers.

Field-effect transistor bioassay for ultrasensitive detection of folate receptor 1 by ligand-protein interaction

A miniaturized and integrated bioassay was developed based on molybdenum disulfide (MoS₂) field-effect transistor (FET) functionalized with bovine serum albumin-folic acid (BSA-FA) for monitoring FOLR1. We performed the electrical test of FOLR1 within the range 100 fg/mL to 10 ng/mL, and the limit of detection was 0.057 pg/mL. The ultrahigh sensitivity of the bioassay was realized by ligand-protein interaction between FA and FOLR1, with a ligand-protein binding ratio of 3:1. The formation of FA-FOLR1 was confirmed with ELISA. The binding affinity dissociation constant K_D was 12 ± 6 pg/mL. This device can work well for FOLR1 detection in human serum, which presents its promising application in point-of-care diagnosis. This study supports the future applications of such ligand-protein-based bioassays in the clinical practices. Graphical abstract MoS₂-based FET device for detecting folate receptor 1 (FOLR1) was fabricated. The molecular folic acid as a probe can specifically bound to FOLR1 with a high affinity.

Rapid Computer-Aided Diagnosis of Stroke by Serum Metabolic Fingerprint Based Multi-Modal Recognition

Stroke is a leading cause of mortality and disability worldwide, expected to result in 61 million disability-adjusted life-years in 2020. Rapid diagnostics is the core of stroke management for early prevention and medical treatment. Serum metabolic fingerprints (SMFs) reflect underlying disease progression, predictive of patient phenotypes. Deep learning (DL) encoding SMFs with clinical indexes outperforms single biomarkers, while posing challenges with poor prediction to interpret by feature selection. Herein, rapid computer-aided diagnosis of stroke is performed using SMF based multi-modal recognition by DL, to combine adaptive machine learning with a novel feature selection approach. SMFs are extracted by nano-assisted laser desorption/ionization mass spectrometry (LDI MS), consuming 100 nL of serum in seconds. A multi-modal recognition is constructed by integrating SMFs and clinical indexes with an enhanced area under curve (AUC) up to 0.845 for stroke screening, compared to single-modal diagnosis by only SMFs or clinical indexes. The prediction of DL is addressed by selecting 20 key metabolite features with differential regulation through a saliency map approach, shedding light on the molecular mechanisms in stroke. The approach highlights the emerging role of DL in precision medicine and suggests an expanding utility for computational analysis of SMFs in stroke screening.

Zirconia Hybrid Nanoshells for Nutrient and Toxin Detection

Monitoring milk quality is of fundamental importance in food industry, because of the nutritional value and resulting position of milk in daily diet. The detection of small nutrients and toxins in milk is challenging, considering high sample complexity and low analyte abundance. In addition, the slow analysis and tedious sample preparation hinder the large-scale application of conventional detection techniques. Herein, zirconia hybrid nanoshells are constructed to enhance the performance of laser desorption/ionization mass spectrometry (LDI MS). Zirconia nanoshells with the optimized structures and compositions are used as matrices in LDI MS and achieve direct analysis of small molecules from 5 nL of native milk in ≈1 min, without any purification or separation. Accurate quantitation of small nutrient is achieved by introducing isotope into the zirconia nanoshell-assisted LDI MS as the internal standard, offering good consistency to biochemical analysis (BCA) with R²  = 0.94. Further, trace toxin is enriched and identified with limit-of-detection (LOD) down to 4 pm, outperforming the current analytical methods. This work sheds light on the personalized design of material-based tool for real-case bioanalysis and opens up new opportunities for the simple, fast, and cost-effective detection of various small molecules in a broad field.

Machine learning of serum metabolic patterns encodes early-stage lung adenocarcinoma

Early cancer detection greatly increases the chances for successful treatment, but available diagnostics for some tumours, including lung adenocarcinoma (LA), are limited. An ideal early-stage diagnosis of LA for large-scale clinical use must address quick detection, low invasiveness, and high performance. Here, we conduct machine learning of serum metabolic patterns to detect early-stage LA. We extract direct metabolic patterns by the optimized ferric particle-assisted laser desorption/ionization mass spectrometry within 1 s using only 50 nL of serum. We define a metabolic range of 100-400 Da with 143 m/z features. We diagnose early-stage LA with sensitivity~70-90% and specificity~90-93% through the sparse regression machine learning of patterns. We identify a biomarker panel of seven metabolites and relevant pathways to distinguish early-stage LA from controls (p < 0.05). Our approach advances the design of metabolic analysis for early cancer detection and holds promise as an efficient test for low-cost rollout to clinics.

Metabolic Fingerprinting on Synthetic Alloys for Medulloblastoma Diagnosis and Radiotherapy Evaluation

Diagnostics is the key in screening and treatment of cancer. As an emerging tool in precision medicine, metabolic analysis detects end products of pathways, and thus is more distal than proteomic/genetic analysis. However, metabolic analysis is far from ideal in clinical diagnosis due to the sample complexity and metabolite abundance in patient specimens. A further challenge is real-time and accurate tracking of treatment effect, e.g., radiotherapy. Here, Pd-Au synthetic alloys are reported for mass-spectrometry-based metabolic fingerprinting and analysis, toward medulloblastoma diagnosis and radiotherapy evaluation. A core-shell structure is designed using magnetic core particles to support Pd-Au alloys on the surface. Optimized synthetic alloys enhance the laser desorption/ionization efficacy and achieve direct detection of 100 nL of biofluids in seconds. Medulloblastoma patients are differentiated from healthy controls with average diagnostic sensitivity of 94.0%, specificity of 85.7%, and accuracy of 89.9%, by machine learning of metabolic fingerprinting. Furthermore, the radiotherapy process of patients is monitored and a preliminary panel of serum metabolite biomarkers is identified with gradual changes. This work will lead to the application-driven development of novel materials with tailored structural design and establishment of new protocols for precision medicine in near future.

Biomimetic immunomagnetic gold hybrid nanoparticles coupled with inductively coupled plasma mass spectrometry for the detection of circulating tumor cells

Immunomagnetic beads are important tools for the isolation and detection of circulating tumor cells (CTCs). However, the current immunomagnetic bead technique provides poor CTC separation purity due to nonspecific binding of background cells. Furthermore, immunomagnetic beads have not been appropriately functionalized for enabling CTC analysis and quantification. In this work, bimetallic magnetic gold nanoparticles were prepared and coated with leukocyte membranes to form leukocyte membrane-camouflaged nanoparticles. After conjugation with the antibody of epithelial cell adhesion molecule (EpCAM), the biomimetic immunomagnetic gold nanoparticles (CM-Fe₃O₄@Au-Ab) showed a high specific recognition ability on mock (EpCAM-positive) CTCs and a reduced interaction with leukocytes. We subsequently optimized the conditions for CTC separation, including the concentration of nanoparticles and the incubation time. Under the optimized conditions, CM-Fe₃O₄@Au-Ab exhibited high CTC capture efficiency with negligible background cell binding in mock clinical blood samples. More importantly, gold probes were tagged on the surface of these separated CTCs. When coupled with ICP-MS analysis, the number of CTCs and gold signals exhibited a good linear relationship, and a low limit of detection was obtained, enabling us to estimate the number of CTCs in blood samples. Hence, we expected that CM-Fe₃O₄@Au-Ab could provide an opportunity to surmount the limitations of current CTC detection.

FeOOH@Metal-Organic Framework Core-Satellite Nanocomposites for the Serum Metabolic Fingerprinting of Gynecological Cancers

High-throughput metabolic analysis is of significance in diagnostics, while tedious sample pretreatment has largely hindered its clinic application. Herein, we designed FeOOH@ZIF-8 composites with enhanced ionization efficiency and size-exclusion effect for laser desorption/ionization mass spectrometry (LDI-MS)-based metabolic diagnosis of gynecological cancers. The FeOOH@ZIF-8-assisted LDI-MS achieved rapid, sensitive, and selective metabolic fingerprints of the native serum without any enrichment or purification. Further analysis of extracted serum metabolic fingerprints successfully discriminated patients with gynecological cancers (GCs) from healthy controls and also differentiated three major subtypes of GCs. Given the low cost, high-throughput, and easy operation, our approach brings a new dimension to disease analysis and classification.

Negative depletion mediated brightfield circulating tumour cell identification strategy on microparticle-based microfluidic chip

Background

The most convenient circulating tumor cells (CTCs) identification method is direct analysis of cells under bright field microscopy by which CTCs can be comprehensive studied based on morphology, phenotype or even cellular function. However, universal cell markers and a standard tumour cell map do not exist, thus limiting the clinical application of CTCs.

Results

This paper focuses on an automatic and convenient negative depletion strategy for circulating tumour cell identification under bright field microscopy. In this strategy, immune microparticles (IMPs) are applied to negatively label white blood cells rather than the tumour cells, such that tumour cells can be directly distinguished under brightfield of the microscopy. In this way, all of the heterogeneous tumour cells and their phenotype properties can be retained for further cancer-related studies. In addition, a wedge-shaped microfluidic chip is constructed for heterogeneous CTC pre-purification and enrichment by size, thus significantly decreasing the interference of haematological cells. Additionally, all cell treatments are processed automatically, and the tumour cells can be rapidly counted and distinguished via customized cell analytical software, showing high detection efficiency and automation. This IMPs based negative cell labelling strategy can also be combined with other classic cell identification methods, thus demonstrating its excellent compatibility.

Conclusion

This identification strategy features simple and harmless for tumour cells, as well as excellent accuracy and efficiency. And the low equipment demand and high automation level make it promise for extensive application in basic medical institutions.

Design of Functional Magnetic Nanocomposites for Bioseparation

Magnetic materials have been widely used in bioseparation in recent years due to their good biocompatibility, magnetic properties, and high binding capacity. In this review, we provide a brief introduction on the preparation and bioseparation applications of magnetic materials including the synthesis and surface modification of magnetic nanoparticles as well as the preparation and applications of magnetic nanocomposites in the separation of proteins, peptides, cells, exosomes and blood. The current limitations and remaining challenges in the fabrication process of magnetic materials for bioseparation will be also detailed.

Diagnosis and prognosis of myocardial infarction on a plasmonic chip

Cardiovascular diseases lead to 31.5% of deaths globally, and particularly myocardial infarction (MI) results in 7.4 million deaths per year. Diagnosis of MI and monitoring for prognostic use are critical for clinical management and biomedical research, which require advanced tools with accuracy and speed. Herein, we developed a plasmonic gold nano-island (pGold) chip assay for diagnosis and monitoring of MI. On-chip microarray analysis of serum biomarkers (e.g., cardiac troponin I) afforded up to 130-fold enhancement of near-infrared fluorescence for ultra-sensitive and quantitative detection within controlled periods, using 10 μL of serum only. The pGold chip assay achieved MI diagnostic sensitivity of 100% and specificity of 95.54%, superior to the standard chemiluminescence immunoassay in cardiovascular clinics. Further, we monitored biomarker concentrations regarding percutaneous coronary intervention for prognostic purpose. Our work demonstrated a designed approach using plasmonic materials for enhanced diagnosis and monitoring for prognostic use towards point-of-care testing.

Bead based facile assay for sensitive quantification of native state green fluorescent protein

A facile method for the quantification of native state protein is strongly required to accurately determine the amount of expressed protein of interest. Here we report a simple bead-based assay, which can sensitively quantify the amount of native state green fluorescent protein using Ni-NTA (nickel-nitrilotriacetic acid)-modified microbead particles. The bead-based method is simple and straightforward to perform and it showed a highly sensitive capability to detect the expressed fluorescent protein because of the enriched fluorescent protein on the beads.

Rapid Label-Free Isolation of Circulating Tumor Cells from Patients' Peripheral Blood Using Electrically Charged Fe3O4 Nanoparticles

Isolation of circulating tumor cells (CTCs) in peripheral blood from cancer patients bears critical importance for evaluation of therapeutic efficacy. The current CTC isolation strategies are majorly relying on either protein biomarkers or dimensional features of CTCs. In this study, we present a new methodology for CTC detection and isolation based on the surface charge of cancer cells, a bioelectrical manifestation of the "Warburg effect." Negative surface charge is a direct consequence of glycolysis of cancer cells, which can be utilized as an effective biophysical marker for CTC detection and isolation. Upon cancer cells-nanoparticle interaction via optimum incubation, serum protein-coated electrically charged nanoparticles can trap different cancer cells independent of their epithelial protein expression. In fetal bovine serum , the poly(ethyleneimine)-functionalized Fe₃O₄ nanoparticles, surface-decorated with protein corona, are able to efficiently capture CTCs from blood samples of colorectal cancer patients.  2-8 CTCs has been isolated from 1 mL of blood and identified by immunostaining fluorescence in situ hybridization and immunofluorescence staining in all 25 colorectal cancer patients at varied stages, while only 0-1 CTC was detected from blood samples of 10 healthy donors. Diverse CTC subpopulations of heteroploids and biomarker expression can also be detected in this strategy. The label-free, charge-based CTC method shows promise in cancer diagnosis and prognosis paving a new path for liquid biopsy.

Synthesis of iron oxide nanocube patched Janus magnetic nanocarriers for cancer therapeutic applications

Iron oxide nanocube patched Janus magnetic porous silica nanocarriers are synthesized and it is expected to be used for a new type of multifunctional carriers in image guided cancer therapeutic applications.

Urine Metabolic Fingerprints Encode Subtypes of Kidney Diseases

Metabolic fingerprints of biofluids encode diverse diseases and particularly urine detection offers complete non-invasiveness for diagnostics of the future. Present urine detection affords unsatisfactory performance and requires advanced materials to extract molecular information, due to the limited biomarkers and high sample complexity. Herein, we report plasmonic polymer@Ag for laser desorption/ionization mass spectrometry (LDI-MS) and sparse-learning-based metabolic diagnosis of kidney diseases. Using only 1 μL of urine without enrichment or purification, polymer@Ag afforded urine metabolic fingerprints (UMFs) by LDI-MS in seconds. Analysis by sparse learning discriminated lupus nephritis from various other non-lupus nephropathies and controls. We combined UMFs with urine protein levels (UPLs) and constructed a new diagnostic model to characterize subtypes of kidney diseases. Our work guides urine-based diagnosis and leads to new personalized analytical tools for other diseases.

Label-Free Detection of Transferrin Receptor by a Designed Ligand-Protein Sensor

Advanced detection of biomarkers in biofluids plays an important role in disease diagnosis and prognosis. Current techniques with pre-labelling suffer from high cost and complicated operation, etc. Herein, we designed a label-free electrochemical biosensor for rapid detection of transferrin receptor with desirable linear range, sensitivity, specificity, reproducibility, and stability for practical applications.

Magnetic Particle Bioconjugates: A Versatile Sensor Approach

: Nanomaterial biosensors have revolutionized the entire scientific, technology, biomedical, materials science, and engineering fields. Among all nanomaterials, magnetic nanoparticles, microparticles, and beads are unique in offering facile conjugation of biorecognition probes for selective capturing of any desired analytes from complex real sample matrices (e.g., biofluids such as whole blood, serum, urine and saliva, tissues, food, and environmental samples). In addition, rapid separation of the particle-captured analytes by the simple use of a magnet for subsequent detection on a sensor unit makes the magnetic particle sensor approach very attractive. The easy magnetic isolation feature of target analytes is not possible with other inorganic particles, both metallic (e.g., gold) and non-metallic (e.g., silica), which require difficult centrifugation and separation steps. Magnetic particle biosensors have thus enabled ultra-low detection with ultra-high sensitivity that has traditionally been achieved only by radioactive assays and other tedious optical sources. Moreover, when traditional approaches failed to selectively detect low-concentration analytes in complex matrices (e.g., colorimetric, electrochemistry, and optical methods), magnetic particle-incorporated sensing strategies enabled sample concentration into a defined microvolume of large surface area particles for a straightforward detection. The objective of this article is to highlight the ever-growing applications of magnetic materials for the detection of analytes present in various real sample matrices. The central idea of this paper was to show the versatility and advantages of using magnetic particles for a variety of sample matrices and analyte types and the adaptability of different transducers with the magnetic particle approaches.

A Magnetic Dynamic Microbiointerface with Biofeedback Mechanism for Cancer Cell Capture and Release

Dynamic biointerfaces with reversible surface bioactivities enable dynamic modulation of cell-material interactions, thus attracting great attention in biomedical science. Herein, we demonstrated a paradigm shift of dynamic biointerfaces from macroscopical substrates to micron-sized particles by reversible engineering of a phenylboronic acid (PBA)-functionalized magnetic microbead with mussel-inspired cancer cell-targeting peptide. Due to reversible catechol-boronate interactions between the peptides and microbeads, the micron-sized dynamic biointerface exhibited sugar-responsive cancer-targeting activity, showing the potential as a microplatform for magnetic and noninvasive isolation of cancer cells through natural biofeedback mechanism (e.g., human glycemic volatility). Our results demonstrated that the dynamic magnetic platform was capable of selective cancer cell capture (∼85%) and sugar-triggered release of them (>93%) in cell culture medium with high efficiency. More importantly, by using this platform, a decent number of target cells (∼23 on average) could be magnetically isolated and identified from artificial CTC blood samples (1 mL) spiked with 100 cancer cells. In view of the biomimetic nature, high capture efficiency, excellent selectivity, and superiority in cell separation and purification processes, the dynamic magnetic microplatform reported here would be a promising and general tool for rare cell detection and separation and cell-based disease diagnosis.

Field-responsive colloidal assemblies defined by magnetic anisotropy

Particle dispersions provide a promising tool for the engineering of functional materials that exploit self-assembly of complex structures. Dispersion made from magnetic colloidal particles is a great choice; they are biocompatible and remotely controllable among many other advantages. However, their dominating dipolar interaction typically limits structural complexity to linear arrangements. This paper shows how a magnetostatic equilibrium state with noncollinear arrangement of the magnetic moments, as reported for ferromagnetic Janus particles, enables the controlled self-organization of diverse structures in two dimensions via constant and low-frequency external magnetic fields. Branched clusters of staggered chains, compact clusters, linear chains, and dispersed single particles can be formed and interconverted reversibly in a controlled way. The structural diversity is a consequence of both the inhomogeneity and the spatial extension of the magnetization distribution inside the particles. We draw this conclusion from calculations based on a model of spheres with multiple shifted dipoles. The results demonstrate that fundamentally new possibilities for responsive magnetic materials can arise from interactions between particles with a spatially extended, anisotropic magnetization distribution.

Janus particles: design, preparation, and biomedical applications

Janus particles with an anisotropic structure have emerged as a focus of intensive research due to their diverse composition and surface chemistry, which show excellent performance in various fields, especially in biomedical applications. In this review, we briefly introduce the structures, composition, and properties of Janus particles, followed by a summary of their biomedical applications. Then we review several design strategies including morphology, particle size, composition, and surface modification, that will affect the performance of Janus particles. Subsequently, we explore the synthetic methodologies of Janus particles, with an emphasis on the most prevalent synthetic method (surface nucleation and seeded growth). Following this, we highlight Janus particles in biomedical applications, especially in drug delivery, bio-imaging, and bio-sensing. Finally, we will consider the current challenges the materials face with perspectives in the future directions.