Thermoresponsive drug delivery systems are designed for the controlled and targeted release of therapeutic payload. These systems exploit hyperthermic temperatures (>39°C), which may be applied by some external means or due to an encountered symptom in inflammatory diseases such as cancer and arthritis. The objective of this paper was to provide some solid evidence in support of the hypothesis that solid lipid nanoparticles (SLNs) can be used for thermoresponsive targeting by undergoing solid-liquid phase transition at their melting point (MP). Thermoresponsive lipid mixtures were prepared by mixing solid and liquid natural fatty acids, and their MP was measured by differential scanning calorimetry (DSC). SLNs (MP 39°C) containing 5-fluorouracil (5-FU) were synthesized by hot melt encapsulation method, and were found to have spherical shape (transmission electron microscopy studies), desirable size (<200 nm), and enhanced physicochemical stability (Fourier transform infrared spectroscopy analysis). We observed a sustained release pattern (22%-34%) at 37°C (5 hours). On the other hand, >90% drug was released at 39°C after 5 hours, suggesting that the SLNs show thermoresponsive drug release, thus confirming our hypothesis. Drug release from SLNs at 39°C was similar to oleic acid and linoleic acid nanoemulsions used in this study, which further confirmed that thermoresponsive drug release is due to solid-liquid phase transition. Next, a differential pulse voltammetry-based electrochemical chemical detection method was developed for quick and real-time analysis of 5-FU release, which also confirmed thermoresponsive drug release behavior of SLNs. Blank SLNs were found to be biocompatible with human gingival fibroblast cells, although 5-FU-loaded SLNs showed some cytotoxicity after 24 hours. 5-FU-loaded SLNs showed thermoresponsive cytotoxicity to breast cancer cells (MDA-MB-231) as cytotoxicity was higher at 39°C (cell viability 72%-78%) compared to 37°C (cell viability >90%) within 1 hour. In conclusion, this study presents SLNs as a safe, simple, and effective platform for thermoresponsive targeting.

Alzheimer's disease (AD) accounts for about 70% of neurodegenerative diseases and is a cause of cognitive decline and death for one-third of seniors. AD is currently underdiagnosed, and it cannot be effectively prevented. Aggregation of amyloid-β (Aβ) proteins has been linked to the development of AD, and it has been established that, under pathological conditions, Aβ proteins undergo structural changes to form β-sheet structures that are considered neurotoxic. Numerous intensive in vitro studies have provided detailed information about amyloid polymorphs; however, little is known on how amyloid β-sheet-enriched aggregates can cause neurotoxicity in relevant settings. We used scattering-type scanning near-field optical microscopy (s-SNOM) to study amyloid structures at the nanoscale, in individual neurons. Specifically, we show that in well-validated systems, s-SNOM can detect amyloid β-sheet structures with nanometer spatial resolution in individual neurons. This is a proof-of-concept study to demonstrate that s-SNOM can be used to detect Aβ-sheet structures on cell surfaces at the nanoscale. Furthermore, this study is intended to raise neurobiologists' awareness of the potential of s-SNOM as a tool for analyzing amyloid β-sheet structures at the nanoscale in neurons without the need for immunolabeling.

Imaging of complex (biological) samples in the near-infrared (NIR) is beneficial due to reduced light scattering, absorption, phototoxicity, and autofluorescence. However, there are few NIR fluorescent materials known and suitable for biomedical applications. Here we exfoliate the layered pigment CaCuSi4O10 (Egyptian Blue, EB) via ball milling and facile tip sonication into NIR fluorescent nanosheets (EB-NS). The size of EB-NS can be tailored to diameters <20 nm and heights down to 1 nm. EB-NS fluoresce at 910 nm and the fluorescence intensity correlates with the number of Cu2+ ions. Furthermore, EB-NS display no bleaching and high brightness compared with other NIR fluorophores. The versatility of EB-NS is demonstrated by in-vivo single-particle tracking and microrheology measurements in Drosophila melanogaster embryos. EB-NS can be uptaken by plants and remotely detected in a low-cost stand-off detection setup. In summary, EB-NS have the potential for a wide range of bioimaging applications.

Ultrasound (US) induced transient membrane permeabilisation has emerged as a hugely promising tool for the delivery of exogenous vectors through the cytoplasmic membrane, paving the way to the design of novel anticancer strategies by targeting functional nanomaterials to specific biological sites. An essential step towards this end is the detailed recognition of suitably marked nanoparticles in sonoporated cells and the investigation of the potential related biological effects. By taking advantage of Synchrotron Radiation Fourier Transform Infrared micro-spectroscopy (SR-microFTIR) in providing highly sensitive analysis at the single cell level, we studied the internalisation of a nanoprobe within fibroblasts (NIH-3T3) promoted by low-intensity US. To this aim we employed 20 nm gold nanoparticles conjugated with the IR marker 4-aminothiophenol. The significant Surface Enhanced Infrared Absorption provided by the nanoprobes, with an absorbance increase up to two orders of magnitude, allowed us to efficiently recognise their inclusion within cells. Notably, the selective and stable SR-microFTIR detection from single cells that have internalised the nanoprobe exhibited clear changes in both shape and intensity of the spectral profile, highlighting the occurrence of biological effects. Flow cytometry, immunofluorescence and murine cytokinesis-block micronucleus assays confirmed the presence of slight but significant cytotoxic and genotoxic events associated with the US-nanoprobe combined treatments. Our results can provide novel hints towards US and nanomedicine combined strategies for cell spectral imaging as well as drug delivery-based therapies.

Loss of memory during Alzheimer's disease (AD), a fatal neurodegenerative disorder, is associated with neuronal loss and the aggregation of amyloid proteins into neurotoxic β-sheet enriched structures. However, the mechanism of amyloid protein aggregation is still not well understood due to many challenges when studying the endogenous amyloid structures in neurons or in brain tissue. Available methods either require chemical processing of the sample or may affect the amyloid protein structure itself. Therefore, new approaches, which allow studying molecular structures directly in neurons, are urgently needed. A novel approach is tested, based on label-free optical photothermal infrared super-resolution microspectroscopy, to study AD-related amyloid protein aggregation directly in the neuron at sub-micrometer resolution. Using this approach, amyloid protein aggregates are detected at the subcellular level, along the neurites and strikingly, in dendritic spines, which has not been possible until now. Here, a polymorphic nature of amyloid structures that exist in AD transgenic neurons is reported. Based on the findings of this work, it is suggested that structural polymorphism of amyloid proteins that occur already in neurons may trigger different mechanisms of AD progression.

Nanolayered coatings are proposed for use in microelectronic devices where the size/performance ratio is becoming increasingly important, with the aim to achieve existing quality requirements while reducing the size of the devices and improving their ability to perform stably over multiple cycles. Si-SiO2-W structures have been proposed as a potential material for the fabrication of microelectronic devices. However, before such materials can be implemented in devices, their properties need to be carefully studied. In this study, Si-SiO2-W nanolayered structures were fabricated and subjected to numerous thermal treatment cycles at 150 °C. A total of 33 heating cycles were applied, resulting in a cumulative exposure of 264 h. The changes in chemical bonds and microstructure were monitored using Fourier Transform Infrared spectrometry (FTIR) and scanning electron microscopy (SEM). The FTIR signal at 960 cm-1, indicating the presence of W deposited on SiO2, was selected to characterize the thermal stability during the heating cycles. The estimated signal intensity variation closely resembled the normal inhomogeneity of the nanolayers. The increase in slope intensity was estimated to be 1.7 × 10-5.

The infection control of implants is one of the hot issues in the field of medicine and dentistry. In this study, we prepared gold nanorod-sputtered titania nanotubes on titanium surface, which is the main component of implant material, and aimed to estimate the remote-controlled tetracycline release and resulting antibacterial effects of gold nanorod-sputtered titania nanotubes using near-infrared laser irradiation. Gold nanorods prepared by ion plasma sputtering (aspect ratio = 1:3) showed optical properties like those of chemically synthesized gold nanorods, exhibiting photothermal effects in the near-infrared region, as demonstrated using field-emission scanning electron microscopy, transmission electron microscopy, and diffuse ultraviolet-visible-near-infrared spectrophotometry. In addition, a 2 wt% tetracycline/polycaprolactone mixture was found to be the most suitable experimental group to demonstrate the biological compatibilities and antibacterial activities. The results of antibacterial agar diffusion tests and near-infrared-mediated tetracycline release tests in vivo confirmed that remote-controlled tetracycline elution using near-infrared laser irradiation was highly effective. Therefore, gold nanorod-sputtered titania nanotubes would be expected to enable the continued use of the photothermal therapy of gold nanorods and extend the limited use of titania showing photocatalytic activity only within the ultraviolet-to-near-infrared region.

Control over assembly, orientation, and defect-free growth of metal-organic framework (MOF) films is crucial for their future applications. A layer-by-layer approach is considered a suitable method to synthesize highly oriented films of numerous MOF topologies, but the initial stages of the film growth remain poorly understood. Here we use a combination of infrared (IR) reflection absorption spectroscopy and atomic force microscopy (AFM)-IR imaging to investigate the assembly and growth of a surface mounted MOF (SURMOF) film, specifically HKUST-1. IR spectra of the films were measured with monolayer sensitivity and <10 nm spatial resolution. In contrast to the common knowledge of LbL SURMOF synthesis, we find evidence for the surface-hindered growth and large presence of copper acetate precursor species in the produced MOF thin-films. The growth proceeds via a solution-mediated mechanism where the presence of weakly adsorbed copper acetate species leads to the formation of crystalline agglomerates with a size that largely exceeds theoretical growth limits. We report the spectroscopic characterization of physisorbed copper acetate surface species and find evidence for the large presence of unexchanged and mixed copper-paddle-wheels. Based on these insights, we were able to optimize and automatize synthesis methods and produce (100) oriented HKUST-1 thin-films with significantly shorter synthesis times, and additionally use copper nitrate as an effective synthesis precursor.

Photothermal-induced resonance (PTIR) spectroscopy and imaging with infrared light has seen increasing application in the molecular spectroscopy of biological samples. The appeal of the technique lies in its capability to provide information about IR light absorption at a spatial resolution better than that allowed by light diffraction, typically below 100 nm. In the present work, we tested the capability of the technique to perform measurements with subcellular resolution on intact eukaryotic cells, without drying or fixing. We demonstrate the possibility of obtaining PTIR images and spectra from the nucleus and multiple organelles with high resolution, better than that allowed by diffraction with infrared light. We obtain particularly strong signal from bands typically assigned to acyl lipids and proteins. We also show that while a stronger signal is obtained from some subcellular structures, other large subcellular components provide a weaker or undetectable PTIR response. The mechanism that underlies such variability in response is presently unclear. We propose and discuss different possibilities, addressing thermomechanical, geometrical, and electrical properties of the sample and the presence of cellular water, from which the difference in response may arise.

Interactions between molecules are fundamental in biology. They occur also between amyloidogenic peptides or proteins that are associated with different amyloid diseases, which makes it important to study the mutual influence of two polypeptides on each other's properties in mixed samples. However, addressing this research question with imaging techniques faces the challenge to distinguish different polypeptides without adding artificial probes for detection. Here, we show that nanoscale infrared spectroscopy in combination with 13C, 15N-labeling solves this problem. We studied aggregated amyloid-β peptide (Aβ) and its interaction with an inhibitory peptide (NCAM1-PrP) using scattering-type scanning near-field optical microscopy. Although having similar secondary structure, labeled and unlabeled peptides could be distinguished by comparing optical phase images taken at wavenumbers characteristic for either the labeled or the unlabeled peptide. NCAM1-PrP seems to be able to associate with or to dissolve existing Aβ fibrils because pure Aβ fibrils were not detected after mixing.

Using a scanning near-field optical microscope coupled to an infrared free electron laser (SNOM-IR-FEL) in low-resolution transmission mode, we collected chemical data from whole cervical cells obtained from 5 pre-menopausal, non-pregnant women of reproductive age, and cytologically classified as normal or with different grades of cervical cell dyskaryosis. Imaging data are complemented by demography. All samples were collected before any treatment. Spectra were also collected using attenuated total reflection, Fourier-transform (ATR-FTIR) spectroscopy, to investigate the differences between the two techniques. Results of this pilot study suggests SNOM-IR-FEL may be able to distinguish cervical abnormalities based upon changes in the chemical profiles for each grade of dyskaryosis at designated wavelengths associated with DNA, Amide I/II, and lipids. The novel data sets are the first collected using SNOM-IR-FEL in transmission mode at the ALICE facility (UK), and obtained using whole cells as opposed to tissue sections, thus providing an 'intact' chemical profile. These data sets are suited to complementing future work on image analysis, and/or applying the newly developed algorithm to other datasets collected using the SNOM-IR-FEL approach.

Organic crystals are emerging as mechanically compliant, light-weight and chemically versatile alternatives to the commonly used silica and polymer waveguides. However, the previously reported organic crystals were shown to be able to transmit visible light, whereas actual implementation in telecommunication devices requires transparency in the near-infrared spectral range. Here we demonstrate that single crystals of the amino acid L-threonine could be used as optical waveguides and filters with high mechanical and thermal robustness for transduction of signals in the telecommunications range. On their (00[Formula: see text]) face, crystals of this material have an extraordinarily high Young's modulus (40.95 ± 1.03 GPa) and hardness (1.98 ± 0.11 GPa) for an organic crystal. First-principles density functional theory calculations, used in conjunction with analysis of the energy frameworks to correlate the structure with the anisotropy in the Young's modulus, showed that the high stiffness arises as a consequence of the strong charge-assisted hydrogen bonds between the zwitterions. The crystals have low optical loss in the O, E, S and C bands of the spectrum (1250-1600 nm), while they effectively block infrared light below 1200 nm. This property favors these and possibly other related organic crystals as all-organic fiber-optic waveguides and filters for transduction of information.

Multiprotein adsorption from complex body fluids represents a highly important and complicated phenomenon in medicine. In this work, multiprotein adsorption from diluted human serum at gold and oxidized iron surfaces is investigated at different serum concentrations and pH values. Adsorption-induced changes in surface topography and the total amount of adsorbed proteins are quantified by atomic force microscopy (AFM) and polarization-modulation infrared reflection absorption spectroscopy (PM-IRRAS), respectively. For both surfaces, stronger protein adsorption is observed at pH 6 compared to pH 7 and pH 8. PM-IRRAS furthermore provides some qualitative insights into the pH-dependent alterations in the composition of the adsorbed multiprotein films. Changes in the amide II/amide I band area ratio and in particular side-chain IR absorption suggest that the increased adsorption at pH 6 is accompanied by a change in protein film composition. Presumably, this is mostly driven by the adsorption of human serum albumin, which at pH 6 adsorbs more readily and thereby replaces other proteins with lower surface affinities in the resulting multiprotein film.

By incorporating 1-(2-aminoethyl)piperazine (AEPIP) into a commercial epoxy blend, a bicontinuous microstructure is produced with the selective localization of amine-functionalized graphene nanoplatelets (A-GNPs). This cured blend underwent self-assembly, and the morphology and topology were observed via spectral imaging techniques. As the selective localization of nanofillers in thermoset blends is rarely achieved, and the mechanism remains largely unknown, the optical photothermal infrared (O-PTIR) spectroscopy technique was employed to identify the compositions of microdomains. The A-GNP tends to be located in the region containing higher concentrations of both secondary amine and secondary alcohol; additionally, the phase morphology was found to be influenced by the amine concentration. With the addition of AEPIP, the size of the graphene domains becomes smaller and secondary phase separation is detected within the graphene domain evidenced by the chemical contrast shown in the high-resolution chemical map. The corresponding chemical mapping clearly shows that this phenomenon was mainly induced by the chemical contrast in related regions. The findings reported here provide new insight into a complicated, self-assembled nanofiller domain formed in a multicomponent epoxy blend, demonstrating the potential of O-PTIR as a powerful and useful approach for assessing the mechanism of selectively locating nanofillers in the phase structure of complex thermoset systems.

The concerted action of a large number of individual molecular level events in the formation and growth of fibrillar protein structures creates a significant challenge for differentiating between the relative contributions of different self-assembly steps to the overall kinetics of this process. The characterization of the individual steps is, however, an important requirement for achieving a quantitative understanding of this general phenomenon which underlies many crucial functional and pathological pathways in living systems. In this study, we have applied a kinetic modeling approach to interpret experimental data obtained for the aggregation of a selection of site-directed mutants of the protein S6 from Thermus thermophilus. By studying a range of concentrations of both the seed structures, used to initiate the reaction, and of the soluble monomer, which is consumed during the growth reaction, we are able to separate unambiguously secondary pathways from primary nucleation and fibril elongation. In particular, our results show that the characteristic autocatalytic nature of the growth process originates from secondary processes rather than primary nucleation events, and enables us to derive a scaling law which relates the initial seed concentration to the onset of the growth phase.

This study aims to observe the accelerated aging effect of 60Co gamma (γ) irradiation on poly (methyl methacrylate) (PMMA) under extreme conditions and determine the influence of different media states on aging. PMMA samples were prepared at room temperature under varying media conditions, including air and deionized water immersion. Then, the samples were irradiated with different doses (50, 250, 500, and 1000 KGy) of 60Co γ-rays. The compositional changes of the PMMA samples exposed to the rays at different periods were determined via Fourier transform infrared spectroscopy. The light transmission of the samples was characterized through ultraviolet-visible spectrophotometry, and the surface wettability of the samples was assessed via water contact angle measurements. Surface and microscopic changes in material morphology were analyzed using optical microscopy, ImageJ software, and scanning electron microscopy. Relative molecular mass and glass transition temperature were analyzed via gel permeation chromatography and differential scanning calorimetry. Thus, a comprehensive analysis of the effect of 60Co γ irradiation on the aging properties of PMMA was performed.

Ammonia nitrogen and natural organic matter (NOM) seriously degrade the quality of surface waters. In this study, the optimum preparation conditions of a yeast-chitosan bio-microcapsule of the Candida tropicalis strain, used to treat micro-polluted surface water, were investigated. Fourier transform infrared spectroscopy and scanning electron microscopy were used to characterize the bio-microcapsules. A continuous laboratory-scale reaction apparatus was built to evaluate the engineering applications of the bio-microcapsules and their treatment efficiency for major pollutants in micro-polluted raw water. The yeast-chitosan bio-microcapsules were found to rapidly and effectively remove suspended solids and ammonia nitrogen. Moreover, the bio-microcapsule pre-treatment process was capable of resisting impact loads and fluctuations in water quality. Even at low temperatures (12 °C), the removal rate of ammonia nitrogen still reached 79%. The treatment did not lead to a temporary increase in nitrite concentration, nor to the excessive accumulation of nitrogen. The application of bio-microcapsules is simple; it only requires aeration and certain nutrient substrates, and can be adapted to treat raw drinking water with a poor nutrient substrate, therefore showing promise for future use in engineering applications.

In situ biosurfactant (rhamnolipid) production by Pseudomonas putida CB-100 was achieved during a bioaugmented and biostimulated treatment to remove hydrocarbons from aged contaminated soil from oil well drilling operations. Rhamnolipid production and contaminant removal were determined for several treatments of irradiated and non-irradiated soils: nutrient addition (nitrogen and phosphorus), P. putida addition, and addition of both (P. putida and nutrients). The results were compared against a control treatment that consisted of adding only sterilized water to the soils. In treatment with native microorganisms (non-irradiated soils) supplemented with P. putida, the removal of total petroleum hydrocarbons (TPH) was 40.6%, the rhamnolipid production was 1.54 mg/kg, and a surface tension of 64 mN/m was observed as well as a negative correlation (R = -0.54; p < 0.019) between TPH concentration (mg/kg) and surface tension (mN/m), When both bacteria and nutrients were involved, TPH levels were lowered to 33.7%, and biosurfactant production and surface tension were 2.03 mg/kg and 67.3 mN/m, respectively. In irradiated soil treated with P. putida, TPH removal was 24.5% with rhamnolipid generation of 1.79 mg/kg and 65.6 mN/m of surface tension, and a correlation between bacterial growth and biosurfactant production (R = -0.64; p < 0.009) was observed. When the nutrients and P. putida were added, TPH removal was 61.1%, 1.85 mg/kg of biosurfactants were produced, and the surface tension was 55.6 mN/m. In summary, in irradiated and non-irradiated soils, in situ rhamnolipid production by P. putida enhanced TPH decontamination of the soil.

This paper reports an investigation of the microwave-assisted synthesis of silver nanoparticles (Ag NPs) using extract of stinky bean (Parkia speciosa Hassk) pods (BP). The formation of Ag NPs was identified by instrumental analysis consists of UV-vis spectrophotometry, Fourier-transform infrared (FTIR) spectrophotometry, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and particle size analysis. Furthermore, Ag NPs were used as antibacterial agents against Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa. The results indicate rapid formation of Ag NPs during microwave irradiation with similar properties to those obtained through the aging method. In general, the use of microwave irradiation yields larger particles, and it is affected by volume ratio of the extract to the AgNO3 solution. The prepared materials demonstrated antibacterial activity.

A novel fluorine-containing water-repellent agent (OFAE-SA-BA) was designed and synthesized by emulsion copolymerization, which was used to replace the commercial long fluorocarbon chain water-repellent agent. To improve water repellency, the intermediate and monomer containing two short fluoroalkyl chains were successfully synthesized and characterized by 1H NMR, 13C NMR and FT-IR, respectively. After being treated by the water-repellent agent, the surface chemical composition, molecular weight, thermal stability, surface morphology, wetting behavior, and durability of the modified cotton fabrics were characterized using X-ray photoelectron spectrophotometry (XPS), gel permeation chromatography (GPC), thermal degradation (TG), scanning electron microscopy (SEM), and video-based contact angle goniometry, respectively. The cotton fabric demonstrated water contact angle of 154.1°, both the water and oil repellency rating were grade 4. The durability of water repellency of the treated fabrics only decreased slightly after 30 times, which represented very good washing durability. The finishing agent did not affect the whiteness of the fabric.