Collision and Coalescence of Single Attoliter Oil Droplets on a Pipet Nanopore.

We describe the use of a quartz pipet nanopore to study the collision and coalescence of individual emulsion oil droplets and their subsequent nanopore translocation. Collision and coalescence of single toluene droplets at a nanopore orifice are driven primarily by electroosmosis and electrophoresis and lead to the fast growth of a trapped oil droplet. This results in a stepwise current response due to the coalesced oil droplet increasing its volume and its ability to partially block the nanopore's ionic current, allowing us to use the resistive-pulse method to resolve single droplet collisions. Further growth of the trapped oil droplet leads to a complete blockage of the nanopore and a nearly 100% current decay. The trapped oil droplet shows enormous mechanical stability at lower voltages and stays in its trapped status for hundreds of seconds. An increased voltage can be used to drive the trapped droplet into the pipet pore within several milliseconds. Simultaneous fluorescence imaging and amperometry were performed to examine droplet collision, coalescence, and translocation, further confirming the proposed mechanism of droplet-nanopore interaction. Moreover, we demonstrate the unique ability to perform fast voltammetric measurements on a nanopore-supported attoliter oil droplet and study its voltage-driven ion transfer processes.

Anti-Programmed Cell Death (PD)-1 Immunotherapy for Malignant Tumor: A Systematic Review and Meta-Analysis.

This systematic review and meta-analysis evaluated anti-programmed cell death (PD)-1 immunotherapy (nivolumab or pembrolizumab) for overall efficacy, safety, and effective dose relative to standard chemotherapy or other conventional drugs in the treatment of malignant tumors. We searched the following databases, PubMed, Medline, Embase, Cochrane, Wangfang Data, Weipu, and China National Knowledge Infrastructure, and the reference lists of the selected articles for randomized controlled trials (RCTs) of anti-PD-1 therapies in humans. The outcome measures were overall survival, treatment response, and adverse events. Only four randomized controlled trials met our inclusion criteria. Three of these evaluated responses to nivolumab, whereas one tested pembrolizumab. The result of our analysis suggested that nivolumab may improve the overall response rate in treating melanoma relative to chemotherapy and has few associated adverse events. Similarly, in metastatic melanoma patients, nivolumab had a significant advantage over dacarbazine in terms of 1-year survival, progression-free survival, and objective response rate. Regarding dose levels of nivolumab for patients with metastatic renal cell carcinoma, the outcomes in response to 2 and 10 mg/kg were similar, but both had significant advantages over 0.3 mg/kg. In addition, pembrolizumab showed similar outcomes in response to 2- and 10-mg/kg treatment. Anti-PD-1 immunotherapy appears to be safe and effective for patients with melanoma or metastatic renal cell carcinoma. Our meta-analysis is limited, but additional clinical trials are warranted to verify this preliminary evidence of positive outcomes and before anti-PD-1 therapy can be recommended for routine clinical use.