Enhanced surface acoustic wave cell sorting by 3D microfluidic chip design

We demonstrate an acoustic wave driven microfluidic cell sorter that combines advantages of multilayer device fabrication with planar surface acoustic wave excitation. We harness the strong vertical component of the refracted acoustic wave to enhance cell actuation by using an asymmetric flow field to increase cell deflection. Precise control of the 3-dimensional flow is realized by topographical structures implemented on the top of the microchannel. We experimentally quantify the effect of the structure dimensions and acoustic parameter. The design attains cell sorting rates and purities approaching those of state of the art fluorescence-activated cell sorters with all the advantages of microfluidic cell sorting

Oxidation of acyclic alkenes and allyl and benzyl ethers with DIB/t-BuOOH/Mg(OAc)<inf>2</inf>

Oxidation of (11Z)-1′,2′-didehydrostemofoline with DIB/TBHP/Mg(OAc)2·4H2O resulted in oxidative cleavage of the C-11-C-12 double bond instead of the desired allylic oxidation of the 1-butenyl side chain. Stemofoline gave a similar result. The oxidation of more simple terminal alkenes was regioselective and gave vinyl ketones while allyl and benzyl ethers gave acrylate and benzoate esters, respectively. Allyl and benzyl ethers could be chemoselectively oxidized in the presence of a terminal alkene or benzyl group. Oxidation of an internal alkene was poorly regioselective, in contrast to the oxidation of 1-substituted cyclohexenes. © 2011 Elsevier Ltd. All rights reserved

Lorentz Invariance in Chiral Kinetic Theory

We show that Lorentz invariance is realized nontrivially in the classical action of a massless spin-$\frac12$ particle with definite helicity. We find that the ordinary Lorentz transformation is modified by a shift orthogonal to the boost vector and the particle momentum. The shift ensures angular momentum conservation in particle collisions and implies a nonlocality of the collision term in the Lorentz-invariant kinetic theory due to side jumps. We show that 2/3 of the chiral-vortical effect for a uniformly rotating particle distribution can be attributed to the magnetic moment coupling required by the Lorentz invariance. We also show how the classical action can be obtained by taking the classical limit of the path integral for a Weyl particle.Comment: 5 pages, 1 figur

Alkaloid-like Molecules for Drug Discovery

The alkaloid class of natural compounds is extensively known for their variety of biological activities. A high percentage of currently employed chemotherapeutic drugs - more than 60% for cancer are of plant origin, and many are alkaloids.[1] Synthetic compounds that display similar structures to alkaloids are known as alkaloid-like molecules. Alkaloids are commonly documented to poses pharmacological properties such as antineoplasticity and acetylcholinesterase (AChE) inhibition. The Aristotelia alkaloids (1 and 2) have a broad spectrum of biological activities,[2] several of which contain the same 3-aza-bicyclo[3.3.1]nonane core structure architecture, seen in blue in Figure 2. Figure 1: Aristotelia alkaloids, 1 and 2. As these Alkaloids are both rare and require complex isolation, it is more resourceful to generate libraries of molecules with the same core scaffold through synthetic pathways, such as the Bridging Ritter reaction.[3] Through the use of the Bridging Ritter reaction with (-)-β-pinene (3) and various nitriles, a small library of alkaloid-like molecules has been synthesized. Figure 2: The bridging Ritter reaction of (-)-β-pinene with various nitriles. AChE inhibitors are currently the front line of drugs used for relieving the symptoms of Alzheimer’s disease (AD) by restoring natural levels neurotransmitter acetylcholine, found to be low in the synapse of AD suffers.[4] All of the currently approved AChE inhibitors have severe undesirable side-effects and with the diseases mortality rate expected to increase greatly, it is imperative that more suitable drug candidates be developed. Therefore, these alkaloid-like compounds were screened for AChE inhibitory activity using The TLC bioautographic method[5] and Ellman Assay[6]. A library of 27 alkaloid-like molecules has been synthesised. The library is currently undergoing in-house anticancer testing using the MTS assay[7] against the MDA-MB-231 breast cancer cell line. External screening has revealed one series of compounds to show potent inhibition properties against MCF-7 and one inparticular to be inactive against healthy mammalian (Vero cell line) and human oral cavity carcinoma (KB) respectively. Screening against AChE showed that the current library act only as weak inhibitors but combined with molecular modeling, has provided useful SAR data to guide the synthesis of more potent hits. Of significant interest is the importance the alkene functionality plays in providing activity. The recent finding of our work will be presented in details in this presentation

Acid-base fractions separated from Streblus asper leaf ethanolic extract exhibited antibacterial, antioxidant, anti-acetylcholinesterase, and neuroprotective activities

© 2018 The Author(s). Background: Streblus asper is a well-known plant native to Southeast Asia. Different parts of the plant have been traditionally used for various medicinal purposes. However, there is very little scientific evidence reporting its therapeutic benefits for potential treatment of Alzheimer's disease (AD). The study aimed to evaluate antibacterial, antioxidant, acetylcholinesterase (AChE) inhibition, and neuroprotective properties of S. asper leaf extracts with the primary objective of enhancing therapeutic applications and facilitating activity-guided isolation of the active chemical constituents. Methods: The leaves of S. asper were extracted in ethanol and subsequently fractionated into neutral, acid and base fractions. The phytochemical constituents of each fraction were analyzed using GC-MS. The antibacterial activity was evaluated using a broth microdilution method. The antioxidant activity was determined using DPPH and ABTS radical scavenging assays. The neuroprotective activity against glutamate-induced toxicity was tested on hippocampal neuronal HT22 cell line by evaluating the cell viability using MTT assay. The AChE inhibitory activity was screened by thin-layer chromatography (TLC) bioautographic method. Results: The partition of the S. asper ethanolic leaf extract yielded the highest mass of phytochemical constitutions in the neutral fraction and the lowest in the basic fraction. Amongst the three fractions, the acidic fraction showed the strongest antibacterial activity against gram-positive bacteria. The antioxidant activities of three fractions were found in the order of acidic > basic > neutral, whereas the decreasing order of neuroprotective activity was neutral > basic > acidic. TLC bioautography revealed one component in the neutral fraction exhibited anti-AChE activity. While in the acid fraction, two components showed inhibitory activity against AChE. GC-MS analysis of three fractions showed the presence of major phytochemical constituents including terpenoids, steroids, phenolics, fatty acids, and lipidic plant hormone. Conclusions: Our findings have demonstrated the therapeutic potential of three fractions extracted from S. asper leaves as a promising natural source for neuroprotective agents with additional actions of antibacterials and antioxidants, along with AChE inhibitors that will benefit in the development of new natural compounds in therapies against AD