Characterization and utility of immobilized metal affinity-functionalized cellulose membranes for point-of-care malaria diagnostics.

Immobilized metal affinity chromatography (IMAC) is a well-established technique for protein separation and purification. IMAC has been previously utilized to capture the malaria biomarker histidine-rich protein 2 (HRP2) from blood, enhancing the sensitivity of field-appropriate diagnostic tools such as lateral flow assays. However, little work has been done to translate this technique to a truly field-usable design. In this study, IMAC-functionalized cellulose membranes are created and characterized fully for future use in applied malaria diagnostics. IMAC-functionalized cellulose membranes were investigated across a range of cellulose substrates, IMAC ligands, and divalent transition metals before use in a capture and elution flowthrough workflow. Following characterization and optimization, it was found that iminodiacetic acid bound to Zn(II) was the most promising ligand-metal pair, with three available coordination sites and a molar loading capacity of 57.7 µmol of metal/cm3 of cellulose. Using these parameters, more than 99% of HRP2 was captured from a large-volume lysed blood sample in a simple flow-through assay and 89% of the captured protein was eluted from the membrane using the chelating compound ethylenediaminetetraacetic acid. Use of this enhancement protocol on an in-house HRP2 lateral flow assay (LFA) yielded a limit of detection of 7 parasites/µL, a 15.8x enhancement factor compared to traditional LFA methods.

Inductively coupled plasma optical emission spectroscopy as a tool for evaluating lateral flow assays.

Lateral flow assays (LFAs) are immunochromatographic point-of-care devices that have greatly impacted disease diagnosis through their rapid, inexpensive, and easy-to-use form factor. While LFAs have been successful as field-deployable tools, they have a relatively poor limit of detection when compared to more complex methods. Moreover, most design and manufacturing optimization is achieved through time- and resource-intensive brute-force optimization. Despite increased interests in LFA manufacturing, more quantitative tools are needed to study current manufacturing protocols and therefore, optimize and streamline development of these devices further. In this work, we focus on a critical LFA component, colloidal gold conjugated to a detection antibody, one of the most commonly used reporter elements. This study utilizes inductively coupled plasma optical emission spectroscopy (ICP-OES) in conjunction with a lateral flow reader to quantitatively analyze colloidal gold distributions at the read-out test and control lines, as well as residual gold on the conjugate pad and other flow through regions. Our goals are to develop a more rigorous understanding of current LFA designs as well as a quantitative understanding of shortcomings of operational characteristics for future improvement. To our knowledge, this is the first time that ICP-OES has been used to study the initial distribution of colloidal gold on an unused LFA and its redistribution after a test is performed. Using three different brands of commercially available malaria LFAs, gold content was measured within each section of an LFA at varying parasite test concentrations. As expected, the total mass of gold remained unchanged after LFA use; however, the total mass of initial gold and its redistribution varied among manufacturers. Importantly, there are also some inherent inefficiencies that exist in these commercial LFA designs; for example, only 30% of the total gold deposited onto Brand A LFAs binds to the test and control lines, sections of the test that contain interpretable signal. Using information gathered with this method, future devices could be more purposefully engineered to focus on improved binding efficiency, resulting in reduced costs, improved limit of detection, and diminished test-to-test and manufacturer-to-manufacturer variability.

The DARK Side of Total Synthesis: Strategies and Tactics in Psychoactive Drug Production.

Humankind has used and abused psychoactive drugs for millennia. Formally, a psychoactive drug is any agent that alters cognition and mood. The term "psychotropic drug" is neutral and describes the entire class of substrates, licit and illicit, of interest to governmental drug policy. While these drugs are prescribed for issues ranging from pain management to anxiety, they are also used recreationally. In fact, the current opioid epidemic is the deadliest drug crisis in American history. While the topic is highly politicized with racial, gender, and socioeconomic elements, there is no denying the toll drug mis- and overuse is taking on this country. Overdose, fueled by opioids, is the leading cause of death for Americans under 50 years of age, killing ca. 64,000 people in 2016. From a chemistry standpoint, the question is in what ways, if any, did organic chemists contribute to this problem? In this targeted review, we provide brief historical accounts of the main classes of psychoactive drugs and discuss several foundational total syntheses that ultimately provide the groundwork for producing these molecules in academic, industrial, and clandestine settings.