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Funding Information: The authors thank Jari Leskinen and Virpi Miettinen at SIB Labs of the University of Eastern Finland for technical support in TEM imaging. This work was supported by the Academy of Finland (projects 314412), and the Ganjiang New Area: Program for High‐Level Talents Introduction. Publisher Copyright: © 2022 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH. Transmission electron microscopy (TEM) observations of negatively stained cell membrane (CM)-coated polymeric nanoparticles (NPs) reveal a characteristic core-shell structure. However, negative staining agents can create artifacts that complicate the determination of the actual NP structure. Herein, it is demonstrated with various bare polymeric core NPs, such as poly(lactic-co-glycolic acid) (PLGA), poly(ethylene glycol) methyl ether-block-PLGA, and poly(caprolactone), that certain observed core-shell structures are actually artifacts caused by the staining process. To address this issue, fluorescence quenching was applied to quantify the proportion of fully coated NPs and statistical TEM analysis was used to identify and differentiate whether the observed core-shell structures of CM-coated PLGA (CM−PLGA) NPs are due to artifacts or to the CM coating. Integrated shells in TEM images of negatively stained CM−PLGA NPs are identified as artifacts. The present results challenge current understanding of the structure of CM-coated polymeric NPs and encourage researchers to use the proposed characterization approach to avoid misinterpretations.

We report an advanced drug delivery platform for combination chemotherapy by concurrently incorporating two different drugs into microcompoistes with ratiometric control over the loading degree. Atorvastatin and celecoxib were selected as model drugs due to their different physicochemical properties and synergetic effect on colorectal cancer prevention and inhibition. To be effective in colorectal cancer prevention and inhibition, the produced microcomposite contained hypromellose acetate succinate, which is insoluble in acidic conditions but highly dissolving at neutral or alkaline pH conditions. Taking advantage of the large pore volume of porous silicon (PSi), atorvastatin was firstly loaded into the PSi matrix, and then encapsulated into the pH-responsive polymer microparticles containing celecoxib by microfluidics in order to obtain multi-drug loaded polymer/PSi microcomposites. The prepared microcomposites showed monodisperse size distribution, multistage pH-response, precise ratiometric controlled loading degree towards the simultaneously loaded drug molecules, and tailored release kinetics of the loaded cargos. This attractive microcomposite platform protects the payloads from being released at low pH-values, and enhances their release at higher pH-values, which can be further used for colon cancer prevention and treatment. Overall, the pH-responsive polymer/PSi-based microcomposite can be used as a universal platform for the delivery of different drug molecules for combination therapy.

Insect cold hardiness is often mediated by low molecular weight cryoprotectants, such as sugars, polyols, and amino acids (AA). While many free-living northern insects must cope with extended periods of freezing ambient temperatures (Ta), the ectoparasitic deer ked Lipoptena cervi imago can encounter subfreezing Ta only during a short autumnal period between hatching and host location. Subsequently, it benefits from the body temperature of the cervid host for survival in winter. This study investigated the cold tolerance of the species by determining its lower lethal temperature (100% mortality, LLT100) during faster and slower cold acclimation, by determining the supercooling point (SCP) and by measuring the concentrations of potential low molecular weight cryoprotectants. The LLT100 of the deer ked was approximately -16 ° C, which would enable it to survive freezing nighttime Ta not only in its current area of distribution but also further north. The SCP was -7.8 ° C, clearly higher than the LLT100 , indicating that the deer ked displays freezing tolerance. The concentrations of free AA, especially nonessential AA, were higher in the cold-acclimated deer keds similar to several other insects. The concentrations of proline increased together with γ-aminobutyrate, arginine, asparagine, cystine, glutamate, glutamine, hydroxylysine, sarcosine, serine, and taurine. AA could be hypothesized to act as cryoprotectants by, e.g., protecting enzymes and lipid membranes from damage caused by cold.

In order to improve the bioactivity of porous silicon chemically functionalized by acetylene (PSi―C) and stimulate the calcium-phosphorous (hydroxyapatite) deposition on this material from a simulated body fluid, electrochemical oxidation of the PSi―C templates has been employed. The initial functionalization by acetylene was done at 500 °C in a N 2 + C 2 H 2 gas stream of 1:1 ratio for 15 minutes; further electrochemical oxidation was performed in 80% phosphoric acid. The morphology and chemical composition of initial and oxidized porous structures were studied by the high resolution SEM technique and FTIR spectroscopy. Initial chemical functionalization leads to a very stable (practically bio-inert) material that after electrochemical oxidation becomes bioactive. We observed that the hydroxyapatite phase has been homogeneously deposited on the electrochemically oxidized PSi―C material immersed in the SBF of Kokubo formulae at 36.5 °C just after two weeks. The layer of hydroxyapatite grown on the surface after 30 days of immersion was compact, crystalline and as thick as 5 μm.

In the present work, a possibility to use thermal annealing of porous silicon to enlarge the pore sizes has been studied. The size of the pores can be increased by controlling the annealing temperature and time. The pore enlargements from 10 nm even up to 100 nm can be obtained without destroying the pore structure. In all studied cases, annealing was found to decrease the surface areas and pore volumes of porous silicon, but the effects of annealing as a function of temperature were found to be strongly dependent on the initial porosity of samples. The crystallinity of the annealed samples was studied with XRD and the obtained results were used to explain differences observed in the pore sizes after the HF treatment of annealed samples.

Nanostructured porous silicon (PS) optical filters have been widely proposed for their use in biological and chemical sensing applications. Porous silicon, however, presents a reactive surface that must be adequately passivated in order to achieve the required chemical stability mandatory for sensing applications. In the present work, thermal carbonization by acetylene decomposition (TCAD) is shown to provide sivation of PS internal surface, as well as an enhancement of the device's sensitivity to certain species. Moreover, it is shown that the TCAD process, as opposed to more common oxidation treatments, has only minor effects on the optical properties of PS. Thus, the optical performance of PS interference filters is preserved after the carbonization process.