Dynamic Nuclear Polarization of Selectively 29Si-Enriched Core@shell Silica Nanoparticles.

29Si silica nanoparticles (SiO2 NPs) are promising magnetic resonance imaging (MRI) probes that possess advantageous properties for in vivo applications, including suitable biocompatibility, tailorable properties, and high water dispersibility. Dynamic nuclear polarization (DNP) is used to enhance 29Si MR signals via enhanced nuclear spin alignment; to date, there has been limited success employing DNP for SiO2 NPs due to the lack of endogenous electronic defects that are required for the process. To create opportunities for SiO2-based 29Si MRI probes, we synthesized variously featured SiO2 NPs with selective 29Si isotope enrichment on homogeneous and core@shell structures (shell thickness: 10 nm, core size: 40 nm), and identified the critical factors for optimal DNP signal enhancement as well as the effective hyperpolarization depth when using an exogenous radical. Based on the synthetic design, this critical factor is the proportion of 29Si in the shell layer regardless of core enrichment. Furthermore, the effective depth of hyperpolarization is less than 10 nm between the surface and core, which demonstrates an approximately 40% elongated diffusion length for the shell-enriched NPs compared to the natural abundance NPs. This improved regulation of surface properties facilitates the development of isotopically enriched SiO2 NPs as hyperpolarized contrast agents for in vivo MRI.

Background free in vivo29Si MR imaging with hyperpolarized PEGylated silicon nanoparticles.

This study demonstrated the potential of 50 nm PEGylated Si NPs for high-resolution in vivo29Si MR imaging, emphasizing their biocompatibility and water dispersibility. The acquisition of in vivo Si MR images using the lowest reported dose after subcutaneous and intraperitoneal administration opens new avenues for future 29Si MR studies.

Polyunsaturated fatty acid biosynthesis pathway determines ferroptosis sensitivity in gastric cancer.

Ferroptosis is an iron-dependent regulated necrosis mediated by lipid peroxidation. Cancer cells survive under metabolic stress conditions by altering lipid metabolism, which may alter their sensitivity to ferroptosis. However, the association between lipid metabolism and ferroptosis is not completely understood. In this study, we found that the expression of elongation of very long-chain fatty acid protein 5 (ELOVL5) and fatty acid desaturase 1 (FADS1) is up-regulated in mesenchymal-type gastric cancer cells (GCs), leading to ferroptosis sensitization. In contrast, these enzymes are silenced by DNA methylation in intestinal-type GCs, rendering cells resistant to ferroptosis. Lipid profiling and isotope tracing analyses revealed that intestinal-type GCs are unable to generate arachidonic acid (AA) and adrenic acid (AdA) from linoleic acid. AA supplementation of intestinal-type GCs restores their sensitivity to ferroptosis. Based on these data, the polyunsaturated fatty acid (PUFA) biosynthesis pathway plays an essential role in ferroptosis; thus, this pathway potentially represents a marker for predicting the efficacy of ferroptosis-mediated cancer therapy.

Utilization of chromogenic enzyme substrates for signal amplification in multiplexed detection of biomolecules using surface mass spectrometry.

MicroRNAs (miRNAs) are important post-transcriptional gene regulators and can serve as potential biomarkers for many diseases. Most of the current miRNA detection techniques require purification from biological samples, amplification, labeling, or tagging, which makes quantitative analysis of clinically relevant samples challenging. Here we present a new strategy for the detection of miRNAs with uniformity over a large area based on signal amplification using enzymatic reactions and measurements using time-of-flight secondary ion mass spectrometry (ToF-SIMS), a sensitive surface analysis tool. This technique has high sequence specificity through hybridization with a hairpin DNA probe and allows the identification of single-base mismatches that are difficult to distinguish by conventional mass spectrometry. We successfully detected target miRNAs in biological samples without purification, amplification, or labeling of target molecules. In addition, by adopting a well-known chromogenic enzymatic reaction from the field of biotechnology, we extended the use of enzyme-amplified signal enhancement ToF (EASE-ToF) to protein detection. Our strategy has advantages with respect to scope, quantification, and throughput over the currently available methods, and is amenable to multiplexing based on the outstanding molecular specificity of mass spectrometry (MS). Therefore, our technique not only has the potential for use in clinical diagnosis, but also provides evidence that MS can serve as a useful readout for biosensing to perform multiplexed analysis extending beyond the limitations of existing technology.

Single patient classifier as a prognostic biomarker in pT1N1 gastric cancer: Results from two large Korean cohorts.

OBJECTIVE: Benefits of adjuvant treatment in pT1N1 gastric cancer (GC) remain controversial. Additionally, an effective biomarker for early GC is the need of the hour. The prognostic and predictive roles of single patient classifier (SPC) were validated in stage II/III GC. In this study, we aimed to elucidate the role of SPC as a biomarker for pT1N1 GC. METHODS: The present retrospective biomarker study (NCT03485105) enrolled patients treated for pT1N1 GC between 1996 and 2012 from two large hospitals (the Y cohort and S cohort). For SPC, mRNA expression of four classifier genes (GZMB, WARS, SFRP4 and CDX1) were evaluated by real-time reverse transcription-polymerase chain reaction assay. The SPC was revised targeting pT1 stages and the prognosis was stratified as high- and low-risk group by the expression of SFRP4, a representative epithelial-mesenchymal transition marker. RESULTS: SPC was evaluated in 875 patients (n=391 and 484 in the Y and S cohorts, respectively). Among 864 patients whose SPC result was available, 41 (4.7%) patients experience GC recurrence. According to revised SPC, 254 (29.4%) patients were classified as high risk [123 (31.5%) and 131 (27.1%) in the Y and S cohorts, respectively]. The high risk was related to frequent recurrence in both Y and S cohort (log-rank P=0.023, P<0.001, respectively), while there was no difference byGZMB and WARS expression. Multivariable analyses of the overall-cohort confirmed the high risk of revised SPC as a significant prognostic factor [hazard ratio (HR): 4.402 (2.293-8.449), P<0.001] of GC. A significant difference was not detected by SPC in the prognosis of patients in the presence and absence of adjuvant treatment (log-rank P=0.670). CONCLUSIONS: The present study revealed the revised SPC as a prognostic biomarker of pT1N1 GC and suggested the use of the revised SPC for early-stage GC as like stage II/III.

Co-expression of cancer driver genes: IDH-wildtype glioblastoma-derived tumorspheres.

BACKGROUND: Driver genes of GBM may be crucial for the onset of isocitrate dehydrogenase (IDH)-wildtype (WT) glioblastoma (GBM). However, it is still unknown whether the genes are expressed in the identical cluster of cells. Here, we have examined the gene expression patterns of GBM tissues and patient-derived tumorspheres (TSs) and aimed to find a progression-related gene. METHODS: We retrospectively collected primary IDH-WT GBM tissue samples (n = 58) and tumor-free cortical tissue samples (control, n = 20). TSs are isolated from the IDH-WT GBM tissue with B27 neurobasal medium. Associations among the driver genes were explored in the bulk tissue, bulk cell, and a single cell RNAsequencing techniques (scRNAseq) considering the alteration status of TP53, PTEN, EGFR, and TERT promoter as well as MGMT promoter methylation. Transcriptomic perturbation by temozolomide (TMZ) was examined in the two TSs. RESULTS: We comprehensively compared the gene expression of the known driver genes as well as MGMT, PTPRZ1, or IDH1. Bulk RNAseq databases of the primary GBM tissue revealed a significant association between TERT and TP53 (p < 0.001, R = 0.28) and its association increased in the recurrent tumor (p < 0.001, R = 0.86). TSs reflected the tissue-level patterns of association between the two genes (p < 0.01, R = 0.59, n = 20). A scRNAseq data of a TS revealed the TERT and TP53 expressing cells are in a same single cell cluster. The driver-enriched cluster dominantly expressed the glioma-associated long noncoding RNAs. Most of the driver-associated genes were downregulated after TMZ except IGFBP5. CONCLUSIONS: GBM tissue level expression patterns of EGFR, TERT, PTEN, IDH1, PTPRZ1, and MGMT are observed in the GBM TSs. The driver gene-associated cluster of the GBM single cells were enriched with the glioma-associated long noncoding RNAs.

L-glutamine as a T2 exchange contrast agent.

PURPOSE: The potential of L-glutamine as a T2 exchange contrast agent in MRI was investigated. METHODS: The T2 relaxation rate of L-glutamine solutions prepared in various concentrations was measured at 9.4 T. A series of T2 -weighted images in a mouse cancer model was acquired with an L-glutamine solution infusion. RESULTS: The T2 relaxivity caused by the exchange (R2ex ) at 37°C was 0.069 s-1 mM-1 and 0.102 s-1 mM-1 for glutamine and glutamate solutions at pH = 7.2, respectively. The R2ex of glutamine at pH = 6.1-6.7 was in the 0.097-0.1 s-1 mM-1 range. No significant dependence of T1 on the concentration of glutamine was observed. The dynamic measurement of T2 -weighted images in vivo showed that the glutamine uptake was primarily observed at the localized part of the tumor CONCLUSION: L-glutamine can be used as a T2 exchange contrast agent and images of glutamine uptake in vivo can be acquired.

Deconvolution of diffuse gastric cancer and the suppression of CD34 on the BALB/c nude mice model.

BACKGROUND: Gastric cancer is a considerable burden for worldwide patients. And diffuse gastric cancer is the most insidious subgroup with poor survival. The phenotypic characterization of the diffuse gastric cancer cell line can be useful for gastric cancer researchers. In this article, we aimed to characterize the diffuse gastric cancer cells with MRI and transcriptomic data. We hypothesized that gene expression pattern is associated with the phenotype of the cells and that the heterogeneous enhancement pattern and the high tumorigenicity of SNU484 can be modulated by the perturbation of the highly expressed gene. METHODS: We evaluated the 9.4 T magnetic resonance imaging and transcriptomic data of the orthotopic mice models from diffuse gastric cancer cells such as SNU484, Hs746T, SNU668, and KATO III. We included MKN74 as an intestinal cancer control cell. After comprehensive analysis integrating MRI and transcriptomic data, we selected CD34 and validated the effect by shRNA in the BALB/c nude mice models. RESULTS: SNU484, SNU668, Hs746T, and MKN74 formed orthotopic tumors by the 5 weeks after cell injection. The diffuse phenotype was found in the SNU484 and Hs746T. SNU484 was the only tumor showing the heterogeneous enhancement pattern on T2 images with a high level of CD34 expression. Knockdown of CD34 decreased the round-void shape in the H&E staining (P = 0.028), the heterogeneous T2 enhancement, and orthotopic tumorigenicity (100% vs 66.7%). The RNAseq showed that the suppressed CD34 is associated with the downregulated gene-sets of the extracellular matrix remodeling. CONCLUSION: Suppression of CD34 in the human-originated gastric cancer cell suggests that it is important for the round-void histologic shape, heterogeneous enhancement pattern on MRI, and the growth of gastric cancer cell line.

Contrast-enhanced ultrasound liver imaging reporting and data system for diagnosing hepatocellular carcinoma: A meta-analysis.

BACKGROUND & AIMS: Contrast-enhanced ultrasound (CEUS) Liver Imaging Reporting and Data System (LI-RADS) is a comprehensive system for standardizing CEUS at high risk for hepatocellular carcinoma (HCC). We performed a meta-analysis to determine the diagnostic performance of the CEUS LR-5 for HCC and the pooled proportions of HCCs in each CEUS LI-RADS category. METHODS: We searched multiple databases for studies reporting the diagnostic accuracy of the CEUS LI-RADS. Random-effects model was used to determine summary estimates of the diagnostic performance of CEUS LR-5 and the pooled proportions of HCCs in each CEUS LI-RADS category. Risk of bias and concerns regarding applicability were evaluated with the Quality Assessment of Diagnostic Accuracy Studies-2 tool. RESULTS: Eleven studies were included in the final analysis, which consisted of 5535 observations with 3983 HCCs. The pooled per-observation sensitivity and specificity of the CEUS LR-5 for diagnosing HCC were 69% (95% confidence interval [CI], 64%-73%) and 92% (95% CI, 83%-96%) respectively. The pooled proportions of HCCs were 0% (95% CI, 0-0%) for LR-1, 1% (95% CI, 0%-4%) for CEUS LR-2, 26% (95% CI, 14%-39%) for CEUS LR-3, 77% (95% CI, 68%-86%) for CEUS LR-4, 97% (95% CI, 95%-98%) for CEUS LR-5, 57% (95% CI, 44%-69%) for CEUS LR-M and 100% (95% CI, 93%-100%) for CEUS LR-5V or TIV. CONCLUSIONS: The CEUS LR-5 category showed moderate sensitivity and high specificity for diagnosing HCC. The proportion of HCCs was higher in the higher CEUS LI-RADS categories.

Predictive test for chemotherapy response in resectable gastric cancer: a multi-cohort, retrospective analysis.

BACKGROUND: Adjuvant chemotherapy after surgery improves survival of patients with stage II-III, resectable gastric cancer. However, the overall survival benefit observed after adjuvant chemotherapy is moderate, suggesting that not all patients with resectable gastric cancer treated with adjuvant chemotherapy benefit from it. We aimed to develop and validate a predictive test for adjuvant chemotherapy response in patients with resectable, stage II-III gastric cancer. METHODS: In this multi-cohort, retrospective study, we developed through a multi-step strategy a predictive test consisting of two rule-based classifier algorithms with predictive value for adjuvant chemotherapy response and prognosis. Exploratory bioinformatics analyses identified biologically relevant candidate genes in gastric cancer transcriptome datasets. In the discovery analysis, a four-gene, real-time RT-PCR assay was developed and analytically validated in formalin-fixed, paraffin-embedded (FFPE) tumour tissues from an internal cohort of 307 patients with stage II-III gastric cancer treated at the Yonsei Cancer Center with D2 gastrectomy plus adjuvant fluorouracil-based chemotherapy (n=193) or surgery alone (n=114). The same internal cohort was used to evaluate the prognostic and chemotherapy response predictive value of the single patient classifier genes using associations with 5-year overall survival. The results were validated with a subset (n=625) of FFPE tumour samples from an independent cohort of patients treated in the CLASSIC trial (NCT00411229), who received D2 gastrectomy plus capecitabine and oxaliplatin chemotherapy (n=323) or surgery alone (n=302). The primary endpoint was 5-year overall survival. FINDINGS: We identified four classifier genes related to relevant gastric cancer features (GZMB, WARS, SFRP4, and CDX1) that formed the single patient classifier assay. In the validation cohort, the prognostic single patient classifier (based on the expression of GZMB, WARS, and SFRP4) identified 79 (13%) of 625 patients as low risk, 296 (47%) as intermediate risk, and 250 (40%) as high risk, and 5-year overall survival for these groups was 83·2% (95% CI 75·2-92·0), 74·8% (69·9-80·1), and 66·0% (60·1-72·4), respectively (p=0·012). The predictive single patient classifier (based on the expression of GZMB, WARS, and CDX1) assigned 281 (45%) of 625 patients in the validation cohort to the chemotherapy-benefit group and 344 (55%) to the no-benefit group. In the predicted chemotherapy-benefit group, 5-year overall survival was significantly improved in those patients who had received adjuvant chemotherapy after surgery compared with those who received surgery only (80% [95% CI 73·5-87·1] vs 64·5% [56·8-73·3]; univariate hazard ratio 0·47 [95% CI 0·30-0·75], p=0·0015), whereas no such improvement in 5-year overall survival was observed in the no-benefit group (72·9% [66·5-79·9] in patients who received chemotherapy plus surgery vs 72·5% [65·8-79·9] in patients who only had surgery; 0·93 [0·62-1·38], p=0·71). The predictive single patient classifier groups (chemotherapy benefit vs no-benefit) could predict adjuvant chemotherapy benefit in terms of 5-year overall survival in the validation cohort (pinteraction=0·036 in univariate analysis). Similar results were obtained in the internal evaluation cohort. INTERPRETATION: The single patient classifiers validated in this study provide clinically important prognostic information independent of standard risk-stratification methods and predicted chemotherapy response after surgery in two independent cohorts of patients with resectable, stage II-III gastric cancer. The single patient classifiers could complement TNM staging to optimise decision making in patients with resectable gastric cancer who are eligible for adjuvant chemotherapy after surgery. Further validation of these results in prospective studies is warranted. FUNDING: Ministry of ICT and Future Planning; Ministry of Trade, Industry, and Energy; and Ministry of Health and Welfare.

Functionalized Magnetic PLGA Nanospheres for Targeting and Bioimaging of Breast Cancer.

Superparamagnetic iron oxide nanoparticles (SPIONs) are actively used as highly sensitive imaging probes to provide contrast in MRI. In this study, we propose the use of SPIONs encapsulated with antibody-conjugated poly(lactic-co-glycolic acid) (PLGA) as a potent theragnostic agent. The SPIONs were synthesized by a chemical co-precipitation method of ferric and ferrous ions, and subsequently encapsulated with PLGA by using an emulsification-diffusion method. Herceptin was chemically conjugated to the SPION-encapsulating PLGA nanoparticles to target the human epidermal growth factor receptor 2 (Her2/neu) overexpressing breast cancers. FACS and MR molecular imaging revealed that the Her2/neu overexpressing cell line showed a stronger contrast enhancement than the Her2/neu non-expressing cell lines, and the signal intensity of in vivo MR imaging decreased as the concentration of Herceptin increased. This strategy of encapsulating SPIONs with PLGA will be highly useful in functionalizing magnetic nanoparticles and improving the diagnostic and therapeutic efficacy of a wide array of cancer treatments.

Serially Ordered Magnetization of Nanoclusters via Control of Various Transition Metal Dopants for the Multifractionation of Cells in Microfluidic Magnetophoresis Devices.

A novel method (i.e., continuous magnetic cell separation in a microfluidic channel) is demonstrated to be capable of inducing multifractionation of mixed cell suspensions into multiple outlet fractions. Here, multicomponent cell separation is performed with three different distinguishable magnetic nanoclusters (MnFe2O4, Fe3O4, and CoFe2O4), which are tagged on A431 cells. Because of their mass magnetizations, which can be ideally altered by doping with magnetic atom compositions (Mn, Fe, and Co), the trajectories of cells with each magnetic nanocluster in a flow are shown to be distinct when dragged under the same external magnetic field; the rest of the magnetic characteristics of the nanoclusters are identically fixed. This proof of concept study, which utilizes the magnetization-controlled nanoclusters (NCs), suggests that precise and effective multifractionation is achievable with high-throughput and systematic accuracy for dynamic cell separation.

Success of tumorsphere isolation from WHO grade IV gliomas does not correlate with the weight of fresh tumor specimens: an immunohistochemical characterization of tumorsphere differentiation.

BACKGROUND: A trend of stage-by-stage increase in tumorsphere (TS) formation from glioma samples has been reported. Despite this trend, not all surgical specimens give rise to TSs, even World Health Organization (WHO) grade IV gliomas. Furthermore, it has been reported that differences in overall survival of primary glioblastoma patients depends on the propensity of their tumors to form TSs. However, the weights of fresh specimens vary from one surgical isolate to the next. METHODS: Accordingly, we evaluated the relationship between the weights of surgical specimens in WHO grade IV gliomas with the capacity to isolate TSs. Thirty-five fresh WHO grade IV glioma specimens were separated into two groups, based on whether they were positive or negative for TS isolation, and the relationship between TS isolation and weight of surgical specimens was assessed. RESULTS: We observed no significant difference in the weights of surgical samples in the two groups, and found that the optimal weight of specimens for TSs isolation was 500 mg. CONCLUSION: Thus, contrary to our expectations, the ability to isolate TSs from WHO grade IV glioma specimens was not related to the weight of fresh specimens.

Failure of a patient-derived xenograft for brain tumor model prepared by implantation of tissue fragments.

BACKGROUND: With the continuing development of new anti-cancer drugs comes a need for preclinical experimental models capable of predicting the clinical activity of these novel agents in cancer patients. However existing models have a limited ability to recapitulate the clinical characteristics and associated drug sensitivity of tumors. Among the more promising approaches for improving preclinical models is direct implantation of patient-derived tumor tissue into immunocompromised mice, such as athymic nude or non-obese diabetic/severe combined immunodeficient (NOD/SCID) mice. In the current study, we attempted to develop patient-derived xenograft (PDX) models using tissue fragments from surgical samples of brain tumors. METHODS: In this approach, tiny tissue fragments of tumors were biopsied from eight brain tumor patients-seven glioblastoma patients and one primitive neuroectodermal tumor patient. Two administration methods-a cut-down syringe and a pipette-were used to implant tissue fragments from each patient into the brains of athymic nude mice. RESULTS: In contrast to previous reports, and contrary to our expectations, we found that none of these fragments from brain tumor biopsies resulted in the successful establishment of xenograft tumors. CONCLUSIONS: These results suggest that fragments of surgical specimens from brain tumor patients are unsuitable for implementation of brain tumor PDX models, and instead recommend other in vivo testing platforms for brain tumors, such as cell-based brain tumor models.

Molecular Imaging of CD44-Overexpressing Gastric Cancer in Mice Using T2 MR Imaging.

Novel diagnostic techniques have been developed in many research area using targetable contrast agents with magnetic resonance imaging (MRI) for cancer diagnosis. For cancer diagnosis, the use of MRI with biocompatible targeting moieties and manganese ferrite nanoparticles (MFNPs) is preferred. Thus, we synthesized MFNPs using a thermal decomposition method which enables sensitive T2 or T2 Turbo Spin Echo (TSE) MRI and coated them with hyaluronic acid (HA). The high targeting ability of HA-MFNPs was observed at MKN-45 cells (gastric cancer cell line) which high-expressing CD44 in contrast with MKN-28 cells which low-expressing CD44. We also prepared the gastric cancer mice model using MKN-45 cells which has the stem-like property was implanted into BALB/c nude mice. And then HA-MFNPs of the T2 contrast enhancement effects and targeting ability were investigated by in vivo MR imaging. As a result of these studies, we conclude that HA coated MFNPs can be effectively used as a novel probes for visualizing gastric cancer stem cells.

Galactosylated magnetic nanovectors for regulation of lipid metabolism based on biomarker-specific RNAi and MR imaging.

The specific delivery of ribonucleic acid (RNA) interfering molecules to disease-related cells is still a critical blockade for in vivo systemic treatment. Here, this study suggests a robust delivery carrier for targeted delivery of RNA-interfering molecules using galactosylated magnetic nanovectors (gMNVs). gMNVs are an organic-inorganic polymeric nanomaterial composed of polycationics and magnetic nanocrystal for delivery of RNA-interfering molecules and tracking via magnetic resonance (MR) imaging. In particular, the surface of gMNVs was modified by galactosylgluconic groups for targeted delivering to asialoglycoprotein receptor (ASGPR) of hepatocytes. Moreover, the small interfering RNAs were used to regulate target proteins related with low-density lipoprotein level and in vivo MR imaging was conducted for tracking of nanovectors. The obtained results show that the prepared gMNVs demonstrate potential as a systemic theragnostic nanoplatform for RNA interference and MR imaging.

Gadolinium-based nanoparticles for highly efficient T1-weighted magnetic resonance imaging.

We developed Pyrene-Gadolinium (Py-Gd) nanoparticles as pH-sensitive magnetic resonance imaging (MRI) contrast agents capable of showing a high-Mr signal in cancer-specific environments, such as acidic conditions. Py-Gd nanoparticles were prepared by coating Py-Gd, which is a complex of gadolinium with pyrenyl molecules, with pyrenyl polyethyleneglycol PEG using a nano-emulsion method. These particles show better longitudinal relaxation time (T1) MR signals in acidic conditions than they do in neutral conditions. Furthermore, the particles exhibit biocompatibility and MR contrast effects in both in vitro and in vivo studies. From these results, we confirm that Py-Gd nanoparticles have the potential to be applied for accurate cancer diagnosis and therapy.

Maleimidyl magnetic nanoplatform for facile molecular MRI.

In this study, we developed the maleimidyl magnetic nanoplatform, which enables functional targeting of a biomarker-specific moiety for molecular imaging via MRI. The maleimide group of the maleimidyl magnetic nanoplatform is conjugated with a thiol group without additional crosslinkers and side products. A physicochemical analysis was conducted to verify the effectiveness of the maleimidyl magnetic nanoplatform, and the existence of the maleimidyl group was investigated using the platform. To prepare biomarker-specific MRI probes, a thiolated aptamer and peptide were immobilized onto the maleimidyl group of the maleimidyl magnetic nanoplatform. The fabricated MRI probes were applied to four cancer cell lines: HT1080, MCF7, MKN45, and HEK293T. To investigate the potential of the molecular MRI probe, the target-biomarker specificity was confirmed without serious cytotoxicity, and in vivo MRI analysis using a xenograft mouse model was demonstrated. We believe these results will be useful for fabricating molecular MRI probes for the diagnosis of cancer.

Artificially engineered magnetic nanoparticles for ultra-sensitive molecular imaging.

Successful development of ultra-sensitive molecular imaging nanoprobes for the detection of targeted biological objects is a challenging task. Although magnetic nanoprobes have the potential to perform such a role, the results from probes that are currently available have been far from optimal. Here we used artificial engineering approaches to develop innovative magnetic nanoprobes, through a process that involved the systematic evaluation of the magnetic spin, size and type of spinel metal ferrites. These magnetism-engineered iron oxide (MEIO) nanoprobes, when conjugated with antibodies, showed enhanced magnetic resonance imaging (MRI) sensitivity for the detection of cancer markers compared with probes currently available. Also, we successfully visualized small tumors implanted in a mouse. Such high-performance, nanotechnology-based molecular probes could enhance the ability to visualize other biological events critical to diagnostics and therapeutics.

Nucleic Acid Amplification Circuit-Based Hydrogel (NACH) Assay for One-Step Detection of Metastatic Gastric Cancer-Derived Exosomal miRNA.

Gastric cancer (GC) is recognized as the fifth most prevalent malignant tumor worldwide. It is characterized by diverse clinical symptoms, treatment responses, and prognoses. In GC prognosis, the promotion of epithelial-mesenchymal transition (EMT) fosters cancer cell invasion and metastasis, thereby triggering the dissemination of tumor cells. This study proposes a nucleic acid amplification circuit-based hydrogel (NACH) assay for identifying exosomal miRNA derived from metastatic GC. The NACH assay employs the rolling circle amplification method and targets miRNA-21, a tumor-related oncogene, and miRNA-99a, which promotes EMT. Specific amplification probes for each target are immobilized within the hydrogel, enabling a streamlined, one-step amplification reaction. The NACH assay exhibits a detection limit of 1 fm for miRNA-21 and miRNA-99a, thereby enabling rapid and highly sensitive on-site detection. Performance evaluation using exosomal miRNA extracted from cell culture media, mouse plasma, and human plasma revealed fluorescence intensity patterns similar to those obtained in qRT-PCR. Furthermore, deploying a custom-developed portable fluorometer for the NACH assay allows for diagnostic performance assessment and point-of-care testing using clinical samples from GC patients. These findings emphasize the potential of the NACH assay to be used as a robust tool for the genetic diagnosis of GC based on exosome detection.