Minli You

Household Fluorescent Lateral Flow Strip Platform for Sensitive and Quantitative Prognosis of Heart Failure Using Dual-Color Upconversion Nanoparticles

Heart failure (HF) is the end-stage of cardiovascular diseases, which is associated with a high mortality rate and high readmission rate. Household early diagnosis and real-time prognosis of HF at bedside are of significant importance. Here, we developed a highly sensitive and quantitative household prognosis platform (termed as UC-LFS platform), integrating a smartphone-based reader with multiplexed upconversion fluorescent lateral flow strip (LFS). Dual-color core-shell upconversion nanoparticles (UCNPs) were synthesized as probes for simultaneously quantifying two target antigens associated with HF, i.e., brain natriuretic peptide (BNP) and suppression of tumorigenicity 2 (ST2). With the fluorescent LFS, we achieved the specific detection of BNP and ST2 antigens in spiked samples with detection limits of 5 pg/mL and 1 ng/mL, respectively, both of which are of one order lower than their clinical cutoff. Subsequently, a smartphone-based portable reader and an analysis app were developed, which could rapidly quantify the result and share prognosis results with doctors. To confirm the usage of UC-LFS platform for clinical samples, we detected 38 clinical serum samples using the platform and successfully detected the minimal concentration of 29.92 ng/mL for ST2 and 17.46 pg/mL for BNP in these clinical samples. Comparing the detection results from FDA approved clinical methods, we obtained a good linear correlation, indicating the practical reliability and stability of our developed UC-LFS platform. Therefore, the developed UC-LFS platform is demonstrated to be highly sensitive and specific for sample-to-answer prognosis of HF, which holds great potential for risk assessment and health monitoring of post-treatment patients at home.

Labeling and long-term tracking of bone marrow mesenchymal stem cells in vitro using NaYF4:Yb3+,Er3+ upconversion nanoparticles

UNLABELLED Mesenchymal stem cells (MSCs) hold great promise as cell therapy candidate in clinics. However, the underlying mechanisms remain elusive due to the lack of effective cell tracking approaches during therapeutic processes. In this study, we successfully synthesized and utilized NaYF4:Yb(3+),Er(3+) upconversion nanoparticles (UCNPs) to label and track rabbit bone marrow mesenchymal stem cells (rBMSCs) during the osteogenic differentiation in vitro. To improve their biocompatibility and cellular uptake, we modified the UCNPs with negatively-charged poly(acrylic acid) and positively-charged poly(allylamine hydrochloride) in turns (i.e., PAH-PAA-UCNPs). The effect of cellular uptake of UCNPs on the osteogenic differentiation of rBMSCs was systematically evaluated, and no significant difference was found between rBMSCs labeled with UCNPs (concentration range of 0-50μg/mL) and UCNPs-free rBMSCs in terms of cell viability, ALP activity, osteogenic protein expressions and production of mineralized nodules. Moreover, the PAH-PAA-UCNPs at a concentration of 50μg/mL exhibited the highest biocompatibility and stability, which could well track rBMSCs during the osteogenesis process. These results would provide a positive reference for the application of these lanthanide-doped UCNPs as fluorescent nanoprobes for stem cell tracking to further understand the mechanism of stem cell fate in tissue engineering and stem cell therapy. STATEMENT OF SIGNIFICANCE Upconversion nanoparticles (UCNPs) have attracted increasing attention as alternative probes for tracking various types of cells including stem cells. The reported fluorapatite-based UCNPs with the needle-like morphology showed a little poor performance on stem cell tracking, which was possibly attributed to the low upconversion efficiency and cell labeling efficiency potentially due to nanomaterial composition, crystal structure and shape. Here, we synthesized the positively-charged NaYF4:Yb(3+),Er(3+) UCNPs with hexagonal phase and sphere-like morphology to enhance their upconversion efficiency, biocompatibility and cellular uptake, leading to a successful tracking of rBMSCs in osteogenesis process without impairing cell viability and differentiation capacity. This study provided a necessary reference for the application of UCNPs in stem cell tracking to better understand the mechanism of stem cell fate in tissue engineering, stem cell therapy, etc.

Pen-on-paper strategy for point-of-care testing: Rapid prototyping of fully written microfluidic biosensor

Paper-based microfluidic biosensors have recently attracted increasing attentions in point-of-care testing (POCT) territories benefiting from their affordable, accessible and eco-friendly features, where technologies for fabricating such biosensors are preferred to be equipment free, easy-to-operate and capable of rapid prototyping. In this work, we developed a pen-on-paper (PoP) strategy based on two custom-made pens, i.e., a wax pen and a conductive-ink pen, to fully write paper-based microfluidic biosensors through directly writing both microfluidic channels and electrodes. Particularly, the proposed wax pen is competent to realize one-step fabrication of wax channels on paper, as the melted wax penetrates into paper during writing process without any post-treatments. The practical applications of the fabricated paper-based microfluidic biosensors are demonstrated by both colorimetric detection of Salmonella typhimurium DNA with detection limit of 1nM and electrochemical measurement of glucose with detection limit of 1mM. The developed PoP strategy for making microfluidic biosensors on paper characterized by true simplicity, prominent portability and excellent capability for rapid prototyping shows promising prospect in POCT applications.

Improved LFIAs for highly sensitive detection of BNP at point-of-care

Heart failure (HF) has become a major cause of morbidity and mortality with a significant global economic burden. Although well-established clinical tests could provide early diagnosis, access to these tests is limited in developing countries, where a relatively higher incidence of HF is present. This has prompted an urgent need for developing a cost-effective, rapid and robust diagnostic tool for point-of-care (POC) detection of HF. Lateral flow immunoassay (LFIA) has found widespread applications in POC diagnostics. However, the low sensitivity of LFIA limits its ability to detect important HF biomarkers (e.g., brain natriuretic peptide [BNP]) that are normally present in low concentration in blood. To address this issue, we developed an improved LFIA by optimizing the gold nanoparticle (GNP)–antibody conjugate conditions (e.g., the conjugate pH and the amount of added antibody), the diameter of GNP and the concentration of antibody embedded on the test line and modifying the structure of test strip. Through these improvements, the proposed test strip enabled the detection of BNP down to 0.1 ng/mL within 10–15 min, presenting ~15-fold sensitivity enhancement over conventional lateral flow assay. We also successfully applied our LFIA in the analysis of BNP in human serum samples, highlighting its potential use for clinical assessment of HF. The developed LFIA for BNP could rapidly rule out HF with the naked eye, offering tremendous potential for POC test and personalized medicine.

Capillary blood for point-of-care testing

Abstract Clinically, blood sample analysis has been widely used for health monitoring. In hospitals, arterial and venous blood are utilized to detect various disease biomarkers. However, collection methods are invasive, painful, may result in injury and contamination, and skilled workers are required, making these methods unsuitable for use in a resource-limited setting. In contrast, capillary blood is easily collected by a minimally invasive procedure and has excellent potential for use in point-of-care (POC) health monitoring. In this review, we first discuss the differences among arterial blood, venous blood, and capillary blood in terms of the puncture sites, components, sample volume, collection methods, and application areas. Additionally, we review the most recent advances in capillary blood-based commercial products and microfluidic instruments for various applications. We also compare the accuracy of microfluidic-based testing with that of laboratory-based testing for capillary blood-based disease diagnosis at the POC. Finally, we discuss the challenges and future perspectives for developing capillary blood-based POC instruments.

Antiproliferative Activity and Cellular Uptake of Evodiamine and Rutaecarpine Based on 3D Tumor Models

Evodiamine (EVO) and rutaecarpine (RUT) are promising anti-tumor drug candidates. The evaluation of the anti-proliferative activity and cellular uptake of EVO and RUT in 3D multicellular spheroids of cancer cells would better recapitulate the native situation and thus better reflect an in vivo response to the treatment. Herein, we employed the 3D culture of MCF-7 and SMMC-7721 cells based on hanging drop method and evaluated the anti-proliferative activity and cellular uptake of EVO and RUT in 3D multicellular spheroids, and compared the results with those obtained from 2D monolayers. The drugs’ IC50 values were significantly increased from the range of 6.4–44.1 μM in 2D monolayers to 21.8–138.0 μM in 3D multicellular spheroids, which may be due to enhanced mass barrier and reduced drug penetration in 3D models. The fluorescence of EVO and RUT was measured via fluorescence spectroscopy and the cellular uptake of both drugs was characterized in 2D tumor models. The results showed that the cellular uptake concentrations of RUT increased with increasing drug concentrations. However, the EVO concentrations uptaken by the cells showed only a small change with increasing drug concentrations, which may be due to the different solubility of EVO and Rut in solvents. Overall, this study provided a new vision of the anti-tumor activity of EVO and RUT via 3D multicellular spheroids and cellular uptake through the fluorescence of compounds.

Point-of-Care Periodontitis Testing: Biomarkers, Current Technologies, and Perspectives

Periodontitis has become one of the most universal chronic inflammatory diseases worldwide. Subclinical symptom progression, ultimately leading to permanent damage, calls for early diagnosis and long-term monitoring. However, traditional clinical diagnostic methods are complex and expensive, and cannot meet these requirements. Recently, with more biomarkers and the development of new technologies, various point-of-care testing (POCT) platforms have been developed for periodontitis diagnosis and monitoring. These are easy to perform, rapid, low-cost, and are perfectly suited for high-frequency diagnosis of periodontitis at the point-of-care (POC). We summarize existing biomarkers of different periodontitis stages and recent developed POCT platforms (including lab-on-a-chip, paper-based platforms, and chairside tests), discuss their existing challenges and future potential, and provide some inspiration and guidelines for future POC periodontitis testing.