Delivery and Diffusion of Retinal in Dermis and Epidermis Through The Combination of Prodrug Nanoparticles and Detachable Dissolvable Microneedles

To minimize fast chemical degradation of retinal, we convert this aldehyde into proretinal nanoparticles (PRNs) by forming retinylidene moieties on chitosan and allowing the grafted polymers to assemble into nanoparticles, and then load the obtained PRNs into detachable microneedles made of 1:1 (by weight) hyaluronic acid/maltose. An embedment of the PRNs in the solid matrix of microneedles helps improving chemical stability of the grafted retinal; the loaded device can be kept at 25 °C for three months (longest time experimented) with less than 30% degradation of the retinylidene moieties. The presence PRNs in the hyaluronic acid-maltose matrix also help improving mechanical strength of the needles. Administration of PRN-loaded detachable microneedles on fresh porcine ear skin results in complete deposition of an array of microneedles in the skin tissue at the dept that spans both epidermis and dermis, as observed by stereomicroscopic and confocal fluorescence microscopic analyses of the cross-sectioned tissue pieces. Obvious diffusion of the PRNs from the originally embedded site of the needles in the skin tissue to the nearby location can be observed, and even distribution in the tissue is reached at 4 h post administration. Rats administered with single dose of PRN-loaded microneedles show significant increased epidermal thickness as compared to rats administered with unloaded microneedles. Both PRN-loaded microneedles and unloaded microneedles produce no skin irritation in rats.

Regulating the dynamic folding of a DNA hairpin at the expense of a small, molecular fuel

Molecular machines, such as ATPases or motor proteins, couple the catalysis of a chemical reaction, most commonly hydrolysis of nucleotide triphosphates, to their conformational change. In essence, they continuously convert a chemical fuel to drive their motion. An outstanding goal of nanotechnology remains to synthesize a nanomachine with similar functions, precision, and speed. The field of DNA nan- otechnology has given rise to the engineering precision required for such a device. Simultaneously, the field of systems chemistry developed fast chemical reaction cycles that convert fuel to change the function of molecules. In this work, we thus combined a fast, chemical reaction cycle with the precision of DNA nanotechnology to yield kinetic control over the conformational state of a DNA hairpin. Future work on such systems will result in fast and precise DNA nanodevices.

ECORE: A New Fast Automated Quantitative Mineral and Elemental Core Scanner

Scarce platinum group elements (PGE) are mainly concealed in massive sulfides, and finding economically viable ore bodies largely relies on their fast chemical mapping. Most core scanners provide incomplete mineralogical contents, but none also provide a complete chemical analysis including light elements. This study investigates the performance of a fully automated laser-induced breakdown spectroscopy (LIBS) core scanner, the ECORE, by comparing its reliability to a scanning electron microscope-energy dispersive spectroscopy (SEM-EDS) mineral mapper and its speed to infrared diffuse reflectance hyperspectral imagers (IR-HSI). The LIBS elemental imaging has been put to the test in our previous work, as well as the high-resolution mineralogical mapping. This paper reports the scaling up analytical applicability of LIBS as a high performance and high-speed drill core scanner. The analysis of a full core tray in this study is the first and largest 7.62 megapixels image done by a LIBS core scanner to our knowledge. Both high-resolution and low-resolution data are put together to express both mineralogical and chemical content as a function of depth.

Protein–lipid architecture of a cholinergic postsynaptic membrane

The cholinergic postsynaptic membrane is an acetylcholine receptor-rich membrane mediating fast chemical communication at the nerve–muscle synapse. Here, cryo-EM is used to examine the protein–lipid architecture of this membrane in tubular vesicles obtained from the (muscle-derived) electric organ of the Torpedo ray. As reported earlier, the helical arrangement of the protein component of the vesicles facilitates image averaging and enables us to determine how cholesterol and phospholipid molecules are distributed in the surrounding matrix, using headgroup size as a means to discriminate between the two kinds of lipid. It is shown that cholesterol segregates preferentially around the receptors in both leaflets of the lipid bilayer, interacting robustly with specific transmembrane sites and creating a network of bridging microdomains. Cholesterol interactions with the receptor are apparently essential for stabilizing and maintaining its physiological architecture, since the transmembrane structure contracts, involving displacements of the helices at the outer membrane surface by ∼2 Å (1–3 Å), when this lipid is extracted. The microdomains may promote cooperativity between neighbouring receptors, leading to an enhanced postsynaptic response.