Cell separation using tilted-angle standing surface acoustic waves.

Separation of cells is a critical process for studying cell properties, disease diagnostics, and therapeutics. Cell sorting by acoustic waves offers a means to separate cells on the basis of their size and physical properties in a label-free, contactless, and biocompatible manner. The separation sensitivity and efficiency of currently available acoustic-based approaches, however, are limited, thereby restricting their widespread application in research and health diagnostics. In this work, we introduce a unique configuration of tilted-angle standing surface acoustic waves (taSSAW), which are oriented at an optimally designed inclination to the flow direction in the microfluidic channel. We demonstrate that this design significantly improves the efficiency and sensitivity of acoustic separation techniques. To optimize our device design, we carried out systematic simulations of cell trajectories, matching closely with experimental results. Using numerically optimized design of taSSAW, we successfully separated 2- and 10-µm-diameter polystyrene beads with a separation efficiency of ∼ 99%, and separated 7.3- and 9.9-µm-polystyrene beads with an efficiency of ∼ 97%. We illustrate that taSSAW is capable of effectively separating particles-cells of approximately the same size and density but different compressibility. Finally, we demonstrate the effectiveness of the present technique for biological-biomedical applications by sorting MCF-7 human breast cancer cells from nonmalignant leukocytes, while preserving the integrity of the separated cells. The method introduced here thus offers a unique route for separating circulating tumor cells, and for label-free cell separation with potential applications in biological research, disease diagnostics, and clinical practice.

A lyophilized sterically stabilized liposome-containing docetaxel: in vitro and in vivo evaluation.

OBJECTIVES: In this study, an improved lyophilized PEGylated liposomal formulation of docetaxel (DOC) has been developed. METHODS: PEGylated docetaxel liposome (PL-DOC) was prepared by thin-film evaporation method and lyophilization. The effect of various components of the lipids and their compatibility with DOC on the entrapment efficiency (EE) of liposome was investigated. The lyophilized PL-DOC was characterized by morphology, particle size, zeta potential, EE, release in vitro and stability. Pharmacokinetics and biodistribution in vivo of lyophilized PL-DOC were also investigated. RESULTS: The optimal liposome formulation was egg phosphatidylcholine (EPC):cholesterol (CH):DSPE-PEG2000:DOC = 56:40:4:4 (molar ratio). Sucrose and mannitol were chosen as cryoprotectant in the lyophilization (cryoprotectant-to-lipid (C/L) mass ratio = 8:1). The size of lyophilized PL-DOC was 152.3 ± 1.0 nm with negative charge and the EE was 89.75 ± 1.79%. Compared with nonlyophilized PL-DOC, the lyophilized PL-DOC was more stable at 4 °C for six months. The lyophilized PL-DOC also showed the good stability after reconstituted by 5% glucose injection. In vitro release study of PL-DOC showed that PL-DOC had a sustained release effect. After i.v. administration at the dose of 10 mg/kg in rats, a significant increase in the AUC0-∞, MRT0-∞ and t1/2 was observed in PL-DOC group compared with conventional docetaxel liposome (CL-DOC) and DOC injection (DOC-I) group. Biodistribution studies in mice showed that PL-DOC significantly decreased the uptake by the organs of mononuclear phagocytic system (MPS), such as liver and spleen, while prolonging the retention time of DOC in the plasma. CONCLUSION: Our PEGylated liposome formulation reported in this study could potentially produce viable clinical strategies for improved delivery of DOC for the treatment of human cancer.

Glycyrrhetinic Acid Liposomes Containing Mannose-Diester Lauric Diacid-Cholesterol Conjugate Synthesized by Lipase-Catalytic Acylation for Liver-Specific Delivery.

Mannose-diester lauric diacid-cholesterol (Man-DLD-Chol), as a liposomal target ligand, was synthesized by lipase catalyzed in a non-aqueous medium. Its chemical structure was confirmed by mass spectrometry (MS) and nuclear magnetic resonance (NMR) spectroscopy. Glycyrrhetinic acid (GA) liposomes containing Man-DLD-Chol (Man-DLD-Chol-GA-Lp) were prepared by the film-dispersion method. We evaluated the characterizations of liposomes, drug-release in vitro, the hemolytic test, cellular uptake, pharmacokinetics, and the tissue distributions. The cellular uptake in vitro suggested that the uptake of Man-DLD-Chol-modified liposomes was significantly higher than that of unmodified liposomes in HepG2 cells. Pharmacokinetic parameters indicated that Man-DLD-Chol-GA-Lp was eliminated more rapidly than GA-Lp. In tissue distributions, the targeting efficiency (Te) of Man-DLD-Chol-GA-Lp on liver was 54.67%, relative targeting efficiency (RTe) was 3.39, relative uptake rate (Re) was 4.78, and peak concentration ratio (Ce) was 3.46. All these results supported the hypothesis that Man-DLD-Chol would be an efficient liposomal carrier, and demonstrated that Man-DLD-Chol-GA-Lp has potential as a drug delivery for liver-targeting therapy.

Quantitative and ultrasensitive in situ immunoassay technology for SARS-CoV-2 detection in saliva.

The coronavirus disease 2019 (COVID-19) pandemic has become an immense global health crisis. However, the lack of efficient and sensitive on-site testing methods limits early detection for timely isolation and intervention. Here, we present a quantitative and ultrasensitive in situ immunoassay technology for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) detection in saliva (QUIT SARS-CoV-2). Our nanoporous membrane resonator generates a rapid oscillating flow to purify and concentrate fully intact SARS-CoV-2 virus in saliva by 40-fold for in situ detection of viral antigens based on chemiluminescent immunoassay within 20 min. This method can not only achieve a detection sensitivity below 100 copies/ml of virus, comparable to the bench-top PCR equipment; it can also improve detection specificity via direct monitoring of viral loads. The integrated portable QUIT SARS-CoV-2 system, which enables rapid and accurate on-site viral screening with a high-throughput sample pooling strategy, can be performed in primary care settings and substantially improve the detection and prevention of COVID-19.

Plastic-based acoustofluidic devices for high-throughput, biocompatible platelet separation.

Platelet separation is a crucial step for both blood donation and treatment of essential thrombocytosis. Here we present an acoustofluidic device that is capable of performing high-throughput, biocompatible platelet separation using sound waves. The device is entirely made of plastic material, which renders the device disposable and more suitable for clinical use. We used this device to process undiluted human whole blood, and we demonstrate a sample throughput of 20 mL min-1, a platelet recovery rate of 87.3%, and a red/white blood cell removal rate of 88.9%. We preserved better platelet function and integrity for isolated platelets than those which are isolated using established methods. Our device features advantages such as rapid fabrication, high throughput, and biocompatibility, so it is a promising alternative to existing platelet separation approaches.

Pharmacokinetics and tissue distribution of docetaxel liposome mediated by a novel galactosylated cholesterol derivatives synthesized by lipase-catalyzed esterification in non-aqueous phase.

The purpose of this study is to synthesize a novel galactosylated cholesterol derivative, cholesterol-diethenyl decanedioate-lactitol (CHS-DD-LA) through lipase-catalyzed esterification in non-aqueous and to evaluate the preparation, pharmacokinetics and biodistribution of docetaxel (DOC) liposomes modified with CHS-DD-LA (G-DOC-L), which may actively gather at the liver compared with the conventional DOC liposomes (DOC-L) and commercial dosage form of DOC injection (DOC-i). A rapid and simple liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay was developed for the determination of the DOC concentration in plasma and tissues with Taxol as the internal standard (IS). To measure the liver-targeting effect of the G-DOC-L, relative uptake rate (Re), peak concentration ratio (Ce), targeting efficiency (Te) and relative targeting efficiency (RTe) were reduced as the evaluation parameters. The results showed that the entrapment efficiency, particle size and Zeta potential of G-DOC-L was 76.8 ± 3.5%, 95.6 nm and 27.19 mV, respectively. After i.v. administration at the dose of 2.5 mg/kg in rats, a decrease in the AUC, MRT and an increase in CL (p < 0.05) were observed in the G-DOC-L group compared with DOC-L. All these results suggested that galactose-anchored liposomes could rapidly be removed from the circulation in vivo. The tissue distribution of G-DOC-L was widely different from that of DOC-L. The Re of G-DOC-L, DOC-L on liver was 4.011, 0.102; Ce was 3.391, 0.111; Te was 55.01, 3.08, respectively, demonstrating that G-DOC-L had an excellent effect on liver-targeting, which may help to improve the therapeutic effect of hepatic diseases.

The effects of fluid shear stress on proliferation and osteogenesis of human periodontal ligament cells.

Shear stress is one of the main stress type produced by speech, mastication or tooth movement. The mechano-response of human periodontal ligament (PDL) cells by shear stress and the mechanism are largely unknown. In our study, we investigated the effects of fluid shear stress on proliferation, migration and osteogenic potential of human PDL cells. 6dyn/cm(2) of fluid shear stress was produced in a parallel plate flow chamber. Our results demonstrated that fluid shear stress rearranged the orientation of human PDL cells. In addition, fluid shear stress inhibited human PDL cell proliferation and migration, but increased the osteogenic potential and expression of several growth factors and cytokines. Our study suggested that shear stress is involved in homeostasis regulation in human PDL cells. Inhibiting proliferation and migration potentially induce PDL cells to respond to mechanical stimuli in order to undergo osteogenic differentiation.