Far-red light-triggered cargo release from liposomes b ound to a photosensitizer-cellulose nanofiber hydrogel

In our research we used the anionic nanofibrillar cellulose (ANFC) as a platform for far-red light-induced release of cargo from liposomes. In contrast to previous works, where photosensitizers are usually in the liposomal bilayers, we used a cellulose-binding dye. Our phthalocyanine derivative has been shown to bind very strongly to cellulose and cellulose nanofiber hydrogels, allowing us to place it outside of the liposomes. Both the sensitizer and cationic liposomes bind strongly to the ANFC after mixing, making the system easy to fabricate. Upon light activation, the photosensitizer generates reactive oxygen species (ROS) within the ANFC hydrogel, where the reactive oxygen species oxidize unsaturated lipids in the liposomal membrane, which makes the liposomes more permeable, resulting in on-demand cargo release. We were able to achieve ca. 70 % release of model hydrophilic cargo molecule calcein from the hydrogels with a relatively low dose of light (262 J/cm2) while employing the straightforward fabrication techniques. Our system was remarkably responsive to the far-red light (730 nm), enabling deep tissue penetration. Therefore, this very promising novel cellulose-immobilized photosensitizer liposomal platform could be used as a controlled drug delivery system, which can have applications in externally activated coatings or implants.

Fecal calcium levels of bird nestlings as a potential indicator of species-specific metal sensitivity

Sensitivity of bird species to environmental metal pollution varies but there is currently no general framework to predict species-specific sensitivity. Such information would be valuable from a conservation point-of-view. Calcium (Ca) has antagonistic effects on metal toxicity and studies with some common model species show that low dietary and circulating calcium (Ca) levels indicate higher sensitivity to harmful effects of toxic metals. Here we measured fecal Ca and five other macroelement (potassium K, magnesium Mg, sodium Na, phosphorus P, sulphur S) concentrations as proxies for dietary levels in 66 bird species to better understand their interspecific variation and potential use as an indicator of metal sensitivity in a wider range of species (the main analyses include 39 species). We found marked interspecific differences in fecal Ca concentration, which correlated positively with Mg and negatively with Na, P and S levels. Lowest Ca concentrations were found in insectivorous species and especially aerial foragers, such as swifts (Apodidae) and swallows (Hirundinidae). Instead, ground foraging species like starlings (Sturnidae), sparrows (Passeridae), cranes (Gruidae) and larks (Alaudidae) showed relatively high fecal Ca levels. Independent of phylogeny, insectivorous diet and aerial foraging seem to indicate low Ca levels and potential sensitivity to toxic metals. Our results, together with information published on fecal Ca levels and toxic metal impacts, suggest that fecal Ca levels are a promising new tool to evaluate potential metal-sensitivity of birds, and we encourage gathering such information in other bird species. Information on the effects of metals on breeding parameters in a wider range of bird species would also help in ranking species by their sensitivity to metal pollution.

Development of Robust Cationic Light-Activated Thermosensitive Liposomes: Choosing the Right Lipids

Extensive research has been conducted on cationic light-activated thermosensitive liposomes (CLTSLs) as a means for site-specific and controlled drug release; however, less attention has been given to the stability of these nanoparticles. Selecting the appropriate lipids is crucial for the development of a stable and responsive system. In this study, we investigated the impact of various lipids on the physical properties of cationic light-activated liposomes. Incorporating poly(ethylene glycol) PEG molecules resulted in uniform liposomes with low polydispersity index, while the addition of unsaturated lipid (DOTAP) resulted in extremely leaky liposomes, with almost 80% release in just 10 min of incubation at body temperature. Conversely, the inclusion of cholesterol in the formulation increased liposome stability too much and decreased their sensitivity to stimuli-responsive release, with only 14% release after 2 min of light exposure. To achieve stable and functional CLTSL, we substituted an equivalent amount of unsaturated lipid with a saturated lipid (DPTAP), resulting in stable liposomes at body temperature that were highly responsive to light, releasing 90% of their content in 10 s of light exposure. We also conducted two atomistic molecular dynamics simulations using lipid compositions with saturated and unsaturated lipids to investigate the effect of lipid composition on the dynamical properties of the liposomal lipid bilayer. Our findings suggest that the nature of lipids used to prepare liposomes significantly affects their properties, especially when the drug loading needs to be stable but triggered drug release properties are required at the same time. Selecting the appropriate lipids in the right amount is therefore essential for the preparation of liposomes with desirable properties.

Triplet sensitization enables bidirectional isomerization of diazocine with 130 nm redshift in excitation wavelengths

Diazocines are bridged azobenzenes with phenyl rings connected by a CH2-CH2 group. Despite this rather small structural difference, diazocine exhibits improved properties over azobenzene as a photoswitch and most importantly, its Z configuration is more stable than the E isomer. Herein, we reveal yet another unique feature of this emerging class of photoswitches. In striking contrast to azobenzenes and other photochromes, diazocine can be selectively switched in E → Z direction and most intriguingly from its thermodynamically stable Z to metastable E isomer upon successive excitation of two different triplet sensitizers present in solution at the same time. This approach leads to extraordinary large redshift of excitation wavelengths to perform isomerization i.e. from 400 nm blue to 530 nm green light (Z → E) and from 530 nm green to 740 nm far-red one (E → Z), which falls in the near-infrared window in biological tissue. Therefore, this work opens up of potential avenues for utilizing diazocines for example in photopharmacology, smart materials, light energy harvesting/storage devices, and out-of-equilibrium systems.

Unraveling an Alternative Mechanism in Polymer Self-Assemblies: An Order-Order Transition with Unusual Molecular Interactions between Hydrophilic and Hydrophobic Polymer Blocks

Polymer self-assembly leading to cooling-induced hydrogel formation is relatively rare for synthetic polymers and typically relies on H-bonding between repeat units. Here, we describe a non-H-bonding mechanism for a cooling-induced reversible order-order (sphere-to-worm) transition and related thermogelation of solutions of polymer self-assemblies. A multitude of complementary analytical tools allowed us to reveal that a significant fraction of the hydrophobic and hydrophilic repeat units of the underlying block copolymer is in close proximity in the gel state. This unusual interaction between hydrophilic and hydrophobic blocks reduces the mobility of the hydrophilic block significantly by condensing the hydrophilic block onto the hydrophobic micelle core, thereby affecting the micelle packing parameter. This triggers the order-order transition from well-defined spherical micelles to long worm-like micelles, which ultimately results in the inverse thermogelation. Molecular dynamics modeling indicates that this unexpected condensation of the hydrophilic corona onto the hydrophobic core is due to particular interactions between amide groups in the hydrophilic repeat units and phenyl rings in the hydrophobic ones. Consequently, changes in the structure of the hydrophilic blocks affecting the strength of the interaction could be used to control macromolecular self-assembly, thus allowing for the tuning of gel characteristics such as strength, persistence, and gelation kinetics. We believe that this mechanism might be a relevant interaction pattern for other polymeric materials as well as their interaction in and with biological environments. For example, controlling the gel characteristics could be considered important for applications in drug delivery or biofabrication.

Intracellular Dynamics of Extracellular Vesicles by Segmented Trajectory Analysis

The analysis of nanoparticle (NP) dynamics in live cell studies by video tracking provides detailed information on their interactions and trafficking in the cells. Although the video analysis is not yet routinely used in NP studies, the equipment suitable for the experiments is already available in most laboratories. Here, we compare trajectory patterns, diffusion coefficients, and particle velocities of NPs in A549 cells with a rather simple experimental setup consisting of a fluorescence microscope and openly available trajectory analysis software. The studied NPs include commercial fluorescent polymeric particles and two subpopulations of PC-3 cell-derived extracellular vesicles (EVs). As bioderived natural nanoparticles, the fluorescence intensities of the EVs limited the recording speed. Therefore, we studied the effect of the recording frame rate and analysis parameters to the trajectory results with bright fluorescent commercial NPs. We show that the trajectory classification and the apparent particle velocities are affected by the recording frame rate, while the diffusion constants stay comparable. The NP trajectory patterns were similar for all NP types and resembled intracellular vesicular transport. Interestingly, the EV movements were faster than the commercial NPs, which contrasts with their physical sizes and may indicate a greater role of the motor proteins in their intracellular transports.

Phototoxicity of BODIPY in long-term imaging can be reduced by intramolecular motion

For long-term live-cell fluorescence imaging and biosensing, it is crucial to work with a dye that has high fluorescence quantum yield and photostability without being detrimental to the cells. In this paper, we demonstrate that neutral boron-dipyrromethene (BODIPY)-based molecular rotors have great properties for high-light-dosage demanding live-cell fluorescence imaging applications that require repetitive illuminations. In molecular rotors, an intramolecular rotation (IMR) allows an alternative route for the decay of the singlet excited state (S₁) via the formation of an intramolecular charge transfer state (CT). The occurrence of IMR reduces the probability of the formation of a triplet state (T₁) which could further react with molecular oxygen (³O₂) to form cytotoxic reactive oxygen species, e.g., singlet oxygen (¹O₂). We demonstrate that the oxygen-related nature of the phototoxicity for BODIPY derivatives can be significantly reduced if a neutral molecular rotor is used as a probe. The studied neutral molecular rotor probe shows remarkably lower phototoxicity when compared with both the non-rotating BODIPY derivative and the cationic BODIPY-based molecular rotor in different light dosages and dye concentrations. It is also evident that the charge and localization of the fluorescent probe are as significant as the IMR in terms of the phototoxicity in a long-term live-cell imaging.

Invasive species control with apex predators: increasing presence of wolves is associated with reduced occurrence of the alien raccoon dog

The role of an alien predator in the community depends on its interaction with native predators. The absence of apex predators may facilitate outbreaks of invasive mesopredators, but the effect of apex predators may vary between species and environments. We analysed the occurrence of a common invasive mesopredator in Europe, the raccoon dog (Nyctereutes procyonoides), and native mesopredators, the red fox and the Eurasian badger, in camera-trap data from Finland. The observations in cameras were analysed in relation to the presence of apex predators in the landscape (grey wolf and Eurasian lynx), human density, and habitat. We observed negative effect of increasing presence of wolves and lynxes on the occurrence of raccoon dogs. This effect appeared clear compared to the effects of habitat and human density. The effect of lynxes on raccoon dogs was clearer in areas with short growth season. For the occurrence of badgers, the presence of wolves had a weak negative effect and the presence of lynxes had a positive effect. For the occurrence of red foxes, wolves had a positive effect when agricultural fields were sparse in the landscape and lynxes had no effect. We also observed that the invasive raccoon dog currently appears to be the most common mesopredator within the study area. We conclude that the effect of apex predators on mesopredators depends on the environment and, in our case, was more suppressive on the alien mesopredator than on the native mesopredators. Thus, apex predators can play an important role in controlling invasive mesopredators.

Microfluidic oxygen tolerability screening of nanocarriers for triplet fusion photon upconversion

The full potential of triplet fusion photon upconversion (TF-UC) of providing high-energy photons locally with low-energy excitation is limited in biomedicine and life sciences by its oxygen sensitivity. This hampers the applicability of TF-UC systems in sensors, imaging, optogenetics and drug release. Despite the advances in improving the oxygen tolerability of TF-UC systems, the evaluation of oxygen tolerability is based on comparing the performance at completely deoxygenated (0% oxygen) and ambient (20-21%) conditions, leaving the physiological oxygen levels (0.3-13.5%) neglected. This oversight is not deliberate and is only the result of the lack of simple and predictable methods to obtain and maintain these physiological oxygen levels in an optical setup. Herein, we demonstrate the use of microfluidic chips made of oxygen depleting materials to study the oxygen tolerability of four different micellar nanocarriers made of FDA-approved materials with various oxygen scavenging capabilities by screening their TF-UC performance over physiological oxygen levels. All nanocarriers were capable of efficient TF-UC even in ambient conditions. However, utilizing oxygen scavengers in the oil phase of the nanocarrier improves the oxygen tolerability considerably. For example, at the mean tumour oxygen level (1.4%), nanocarriers made of surfactants and oil phase both capable of oxygen scavenging retained remarkably 80% of their TF-UC emission. This microfluidic concept enables faster, simpler and more realistic evaluation of, not only TF-UC, but any micro or nanoscale oxygen-sensitive system and facilitates their development and implementation in biomedical and life science applications.

Correction: Addressing challenges in the removal of unbound dye from passively labelled extracellular vesicles

[This corrects the article DOI: 10.1039/D1NA00755F.].

Addressing challenges in the removal of unbound dye from passively labelled extracellular vesicles

Studies of extracellular vesicles (EVs), their trafficking and characterization often employ fluorescent labelling. Unfortunately, little attention has been paid thus far to a thorough evaluation of the purification of EVs after labelling, although the presence of an unbound dye may severely compromise the results or even lead to wrong conclusions on EV functionality. Here, we systematically studied five dyes for passive EV labelling and meticulously compared five typical purification methods: ultracentrifugation (UC), ultracentrifugation with discontinuous density gradient (UCG), ultrafiltration (UF), size exclusion chromatography (SEC), and anion exchange chromatography (AEC). A general methodology for evaluation of EV purification efficiency after the labelling was developed and tested to select the purification methods for the chosen dyes. Firstly, we found that some methods initially lead to high EV losses even in the absence of the dye. Secondly, the suitable purification method needs to be found for each particular dye and depends on the physical and chemical properties of the dye. Thirdly, we demonstrated that the developed parameter E _rp (relative purification efficiency) is a useful tool for the pre-screening of the suitable dye-purification method combinations. Additionally, it was also shown that the labelled EVs properly purified from the unbound dye may show significantly reduced contrast and visibility in the target application, e.g. in the live cell fluorescence lifetime imaging.

Azobenzene Photoswitching with Near-Infrared Light Mediated by Molecular Oxygen

Efficient photoisomerization between the cis and the trans states of azobenzenes using low-energy light is desirable for a range of applications in, e.g., photobiology yet challenging to accomplish directly with modified azobenzenes. Herein, we utilize molecular iodine as a photocatalyst to induce indirect cis-to-trans isomerization of 4,4'-dimethoxyazobenzene with 770 nm near-infrared light, showing robustness during more than 1000 cycles in ambient conditions. Intriguingly, the catalysis is mediated by molecular oxygen, and we demonstrate that other singlet-oxygen-generating photosensitizers besides iodine, i.e., palladium phthalocyanine, catalyze the isomerization as well. Thus, we envision that the approach can be further improved by employing other catalysts with suitable photoelectrochemical properties. Further studies are needed to explore the applicability of the approach with other azobenzene derivatives.

Drug diffusivities in nanofibrillar cellulose hydrogel by combined time-resolved Raman and fluorescence spectroscopy

Hydrogels, natural and synthetic origin, are actively studied for their use for implants and payload carriers. These biomaterials for delivery systems have enormous potential in basic biomedical research, drug development, and long-term delivery of biologics. Nanofibrillated cellulose (NFC) hydrogels, both natural and anionic (ANFC) ones, allow drug loading for immediate and controlled release via the slow drug dissolution of solid drug crystals into hydrogel and its subsequent release. This property makes NFC originated hydrogels an interesting non-toxic and non-human origin material as drug reservoir for long-term controlled release formulation or implant for patient care. A compelling tool for studying NFC hydrogels is Raman spectroscopy, which enables to resolve the chemical structures of different molecules in a high-water content like hydrogels, since Raman spectroscopy is insensitive to water molecules. That offers real time investigation of label-free drugs and their release in high-water-content media. Despite the huge potential of Raman spectroscopy in bio-pharmaceutical applications, the strong fluorescence background of many drug samples masking the faint Raman signal has restricted the widespread use of it. In this study we used a Raman spectrometer capable of suppressing the unpleasant fluorescence background by combining a pulsed laser and time-resolved complementary metal-oxide-semiconductor (CMOS) single-photon avalanche diode (SPAD) line sensor for the label-free investigation of Metronidazole and Vitamin C diffusivities in ANFC. The results show the possibility to modulate the ANFC-based implants and drug delivery systems, when the release rate needs to be set to a desired value. More importantly, the now developed label free real-time method is universal and can be adapted to any hydrogel/drug combination for producing reliable drug diffusion coefficient data in complex and heterogeneous systems, where traditional sampling-based methods are cumbersome to use. The wide temporal range of the time-resolved CMOS SPAD sensors makes it possible to capture also the fluorescence decay of samples, giving rise to a combined time-resolved Raman and fluorescence spectroscopy, which provides additional information on the chemical, functional and structural changes in samples.

Comparing the taste-modifying properties of nanocellulose and carboxymethyl cellulose

The taste-modifying properties of nanofibrillar cellulose (NFC) and carboxymethyl cellulose (CMC) are compared for the first time. The samples were prepared in the form of gels, with and without added sweet and bitter taste components. As viscosity itself is known to affect taste perception, the viscosities of NFC and CMC samples were set to the same level as shear rates commonly found in the oral cavity. A trained panel of 10 assessors evaluated the bitterness and sweetness of the samples. Further, the assessors were given an opportunity to describe the samples in free words. The taste-modifying capacities of the thickening agents were at the same level when sweet compounds were added. However, CMC was better able to reduce the bitterness of quinine hydrochloride than NFC, which did not show any bitterness-reduction ability with the compound. This was unexpected, as our previous studies of NFC showed fairly high binding capacity with quinine. The open-ended responses revealed that the NFC-containing samples had an astringent sensation, while certain assessors observed a sensation of saltiness in the CMC samples. This may explain the inability of NFC to mask the bitterness of quinine hydrochloride, as astringency may act as a bitterness enhancer, while saltiness may suppress it. Both thickening agents were perceived as slightly bitter. Our study reveals the need for further assessment of the orosensory properties of NFC, particularly the magnitude and origin of its astringency, before it can be fully utilized in food industry applications.

Expanding excitation wavelengths for azobenzene photoswitching into the near-infrared range via endothermic triplet energy transfer

Developing azobenzene photoswitches capable of selective and efficient photoisomerization by long-wavelength excitation is an enduring challenge. Herein, rapid isomerization from the Z- to E-state of two ortho-functionalized bistable azobenzenes with near-unity photoconversion efficiency was driven by triplet energy transfer upon red and near-infrared (up to 770 nm) excitation of porphyrin photosensitizers in catalytic micromolar concentrations. We show that the process of triplet-sensitized isomerization is efficient even when the sensitizer triplet energy is substantially lower (>200 meV) than that of the azobenzene used. This makes the approach applicable for a wide variety of sensitizer-azobenzene combinations and enables the expansion of excitation wavelengths into the near-infrared spectral range. Therefore, indirect excitation via endothermic triplet energy transfer provides efficient and precise means for photoswitching upon 770 nm near-infared light illumination with no chemical modification of the azobenzene chromophore, a desirable feature in photocontrollable biomaterials.

Reduced Number of Pediatric Orthopedic Trauma Requiring Operative Treatment during COVID-19 Restrictions: A Nationwide Cohort Study

Background and Aims:

The coronavirus outbreak significantly changed the need of healthcare services. We hypothesized that the COVID-19 pandemic decreased the frequency of pediatric fracture operations. We also hypothesized that the frequency of emergency pediatric surgical operations decreased as well, as a result of patient-related reasons, such as neglecting or underestimating the symptoms, to avoid hospital admission.

Materials and Methods:

Nationwide data were individually collected and analyzed in all five tertiary pediatric surgical/trauma centers in Finland. Operations related to fractures, appendicitis, and acute scrotum in children aged above 16 years between March 1 and May 31 from 2017 to 2020 were identified. The monthly frequencies of operations and type of traumas were compared between prepandemic 3 years and 2020.

Results:

Altogether, 1755 patients were identified in five tertiary hospitals who had an emergency operation during the investigation period. There was a significant decrease (31%, p = 0.03) in trauma operations. It was mostly due to reduction in lower limb trauma operations (32%, p = 0.006). Daycare, school, and organized sports–related injuries decreased significantly during the pandemic. These reductions were observed in March and in April. The frequencies of appendectomies and scrotal explorations remained constant.

Conclusion:

According to the postulation, a great decrease in the need of trauma operations was observed during the peak of COVID-19 pandemic. In the future, in case similar public restrictions are ordered, the spared resources could be deployed to other clinical areas. However, the need of pediatric surgical emergencies held stable during the COVID-19 restrictions.

White-tailed eagle (Haliaeetus albicilla) and great cormorant (Phalacrocorax carbo) nestlings as spatial sentinels of Baltic acidic sulphate soil associated metal contamination

Sulphate soils, characterised by low pH conditions, are found worldwide, and are potentially large sources of metal contamination, often exceeding industrial emissions. Metal leaching from sulphate soils has been shown to be harmful to aquatic organisms, but the cascading effect on exposure in apex avian predators has not been studied earlier. With the present study we aimed at evaluating the potential of white-tailed eagle (Haliaeetus albicilla) and great cormorant (Phalacrocorax carbo) nestlings, collected from nests located either in sulphate soil or control areas, for monitoring spatial contaminant trends of metals typically associated with sulphate soils. In blood of white-tailed eagles, the concentrations of aluminium and cobalt were significantly higher in sulphate soil areas. In blood of great cormorants, the concentrations of copper and manganese were so, while the concentration of zinc was found to be lower. Also, we observed an interaction between the latitude and soil type in cobalt and lithium concentrations of great cormorants, showing that concentrations in the sulphate soil associated nestlings rose more steeply towards the north than in the control group. Latitudinal trends of higher concentrations in the south were found in cadmium, manganese, and copper of white-tailed eagle nestlings, while thallium of white-tailed eagle nestlings, and thallium and zinc of great cormorant nestlings showed a latitudinal trend of higher concentrations in the north. Concentrations of several metals correlated positively within a species indicating covariation in metal exposure. Generally, the metal concentrations in both species were similar to levels reported to be below toxicity thresholds in other species. These results indicate, that white-tailed eagle and great cormorant nestling metal burdens may indicate environmental contamination from acidic sulphate soil runoff, and that they may act as indicators of latitudinal gradient identifying different contamination sources.

Surface Stabilization and Dissolution Rate Improvement of Amorphous Compacts with Thin Polymer Coatings: Can We Have It All?

The distinction between surface and bulk crystallization of amorphous pharmaceuticals, as well as the importance of surface crystallization for pharmaceutical performance, is becoming increasingly evident. An emerging strategy in stabilizing the amorphous drug form is to utilize thin coatings at the surface. While the physical stability of systems coated with pharmaceutical polymers has recently been studied, the effect on dissolution performance as a function of storage time, as a further necessary step toward the success of these formulations, has not been previously studied. Furthermore, the effect of coating thickness has not been elucidated. This study investigated the effect of these polymer-coating parameters on the interplay between amorphous surface crystallization and drug dissolution for the first time. The study utilized simple tablet-like coated dosage forms, comprising a continuous amorphous drug core and thin polymer coating (hundreds of nanometers to a micrometer thick). Monitoring included analysis of both the solid-state of the model drug (with SEM, XRD, and ATR FTIR spectroscopy) and dissolution performance (and associated morphology and solid-state changes) after different storage times. Stabilization of the amorphous form (dependent on the coating thickness) and maintenance of early-stage intrinsic dissolution rates characteristic for the unaged amorphous drug were achieved. However, dissolution in the latter stages was likely inhibited by the presence of a polymer at the surface. Overall, this study introduced a versatile coated system for studying the dissolution of thin-coated amorphous dosage forms suitable for different drugs and coating agents. It demonstrated the importance of multiple factors that need to be taken into consideration when aiming to achieve both physical stability and improved release during the shelf life of amorphous formulations.

Endothermic and Exothermic Energy Transfer Made Equally Efficient for Triplet-Triplet Annihilation Upconversion

Expanding the anti-Stokes shift for triplet-triplet annihilation upconversion (TTA-UC) systems with high quantum yields without compromising power density thresholds (I_th) remains a critical challenge in photonics. Our studies reveal that such expansion is possible by using a highly endothermic TTA-UC pair with an enthalpy difference of +80 meV even in a polymer matrix 1000 times more viscous than toluene. Carrying out efficient endothermic triplet-triplet energy transfer (TET) requires suppression of the reverse annihilator-to-sensitizer TET, which was achieved by using sensitizers with high molar extinction coefficients and long triplet state lifetimes as well as optimized annihilator concentrations. Under these conditions, the sensitizer-to-annihilator forward TET becomes effectively entropy driven, yielding upconversion quantum yields comparable to those achieved with the exothermic TTA-UC pair but with larger anti-Stokes shifts and even lower I_th, a previously unattained achievement.

Elevated oxidative stress in pied flycatcher nestlings of eumelanic foster fathers under low rearing temperatures

Striking variation in melanin coloration within natural populations is likely due to the different fitness outcomes of alternative phenotypes in varying environmental conditions. There are two types of melanin: eumelanins yield blackish hues, whereas pheomelanins yield reddish hues. The production of eumelanins requires low levels of glutathione (GSH), which is the most important intracellular antioxidant, whereas the production of pheomelanins requires high levels of GSH. We investigated the oxidative status of male pied flycatchers (Ficedula hypoleuca) with different degrees of melanin coloration under different temperatures during the nestling period. Moreover, we assessed the oxidative status of offspring in relation to their biological or foster father's melanin coloration and ambient temperature. To separate offspring genotype effects and paternal effects in different temperatures, we used a partial cross-foster design. The temperature differently affected the oxidative status of differently colored male pied flycatchers and their foster offspring. When the weather was relatively cold, black males had higher glutathione S-transferase levels compared with brown males, indicating enhanced stress in black males. Foster offspring of black males had a lower ratio between reduced and oxidized GSH followed by higher total amount of GSH than foster offspring of brown males. Thus, foster offspring of black males seem to suffer from oxidative stress under relatively cold weather compared with those of brown males, and vice versa under relatively warm weather. Although differently colored males experienced changes in their oxidative status under different temperatures, the link between paternal melanin coloration and offspring oxidative stress appears to be environmentally induced.

Understanding Dissolution and Crystallization with Imaging: A Surface Point of View

The tendency for crystallization during storage and administration is the most considerable hurdle for poorly water-soluble drugs formulated in the amorphous form. There is a need to better detect often subtle and complex surface crystallization phenomena and understand their influence on the critical quality attribute of dissolution. In this study, the interplay between surface crystallization of the amorphous form during storage and dissolution testing, and its influence on dissolution behavior, is analyzed for the first time with multimodal nonlinear optical imaging (coherent anti-Stokes Raman scattering (CARS) and sum frequency generation (SFG)). Complementary analyses are provided with scanning electron microscopy, X-ray diffraction and infrared and Raman spectroscopies. Amorphous indomethacin tablets were prepared and subjected to two different storage conditions (30 °C/23% RH and 30 °C/75% RH) for various durations and then dissolution testing using a channel flow-through device. Trace levels of surface crystallinity previously imaged with nonlinear optics after 1 or 2 days of storage did not significantly decrease dissolution and supersaturation compared to the freshly prepared amorphous tablets while more extensive crystallization after longer storage times did. Multimodal nonlinear optical imaging of the tablet surfaces after 15 min of dissolution revealed complex crystallization behavior that was affected by both storage condition and time, with up to four crystalline polymorphs simultaneously observed. In addition to the well-known α- and γ-forms, the less reported metastable ε- and η-forms were also observed, with the ε-form being widely observed in samples that had retained significant surface amorphousness during storage. This form was also prepared in the pure form and further characterized. Overall, this study demonstrates the potential value of nonlinear optical imaging, together with more established solid-state analysis methods, to understand complex surface crystallization behavior and its influence on drug dissolution during the development of amorphous drugs and dosage forms.

Pectin and Mucin Enhance the Bioadhesion of Drug Loaded Nanofibrillated Cellulose Films

PURPOSE

Bioadhesion is an important property of biological membranes, that can be utilized in pharmaceutical and biomedical applications. In this study, we have fabricated mucoadhesive drug releasing films with bio-based, non-toxic and biodegradable polymers that do not require chemical modifications.

METHODS

Nanofibrillar cellulose and anionic type nanofibrillar cellulose were used as film forming materials with known mucoadhesive components mucin, pectin and chitosan as functional bioadhesion enhancers. Different polymer combinations were investigated to study the adhesiveness, solid state characteristics, film morphology, swelling, mechanical properties, drug release with the model compound metronidazole and in vitro cytotoxicity using TR146 cells to model buccal epithelium.

RESULTS

SEM revealed lamellar structures within the films, which had a thickness ranging 40-240 μm depending on the film polymer composition. All bioadhesive components were non-toxic and showed high adhesiveness. Rapid drug release was observed, as 60-80% of the total amount of metronidazole was released in 30 min depending on the film formulation.

CONCLUSIONS

The liquid molding used was a straightforward and simple method to produce drug releasing highly mucoadhesive films, which could be utilized in treating local oral diseases, such as periodontitis. All materials used were natural biodegradable polymers from renewable sources, which are generally regarded as safe.

Crystallization Kinetics of an Amorphous Pharmaceutical Compound Using Fluorescence-Lifetime-Imaging Microscopy

Pharmaceutical scientists are increasingly interested in amorphous drug formulations especially because of their higher dissolution rates. Consequently, the thorough characterization and analysis of these formulations are becoming more and more important for the pharmaceutical industry. Here, fluorescence-lifetime-imaging microscopy (FLIM) was used to monitor the crystallization of an amorphous pharmaceutical compound, indomethacin. Initially, we identified different solid indomethacin forms, amorphous and γ- and α-crystalline, on the basis of their time-resolved fluorescence. All of the studied indomethacin forms showed biexponential decays with characteristic fluorescence lifetimes and amplitudes. Using this information, the crystallization of amorphous indomethacin upon storage in 60 °C was monitored for 10 days with FLIM. The progress of crystallization was detected as lifetime changes both in the FLIM images and in the fluorescence-decay curves extracted from the images. The fluorescence-lifetime amplitudes were used for quantitative analysis of the crystallization process. We also demonstrated that the fluorescence-lifetime distribution of the sample changed during crystallization, and when the sample was not moved between measuring times, the lifetime distribution could also be used for the analysis of the reaction kinetics. Our results clearly show that FLIM is a sensitive and nondestructive method for monitoring solid-state transformations on the surfaces of fluorescent samples.

Efficient photon upconversion at remarkably low annihilator concentrations in a liquid polymer matrix: when less is more

A triplet–triplet annihilation upconversion of 24.5% was achieved at a remarkably low 600 μM annihilator concentration in a viscous polymer matrix.

One in Three of Pediatric Tibia Shaft Fractures is Currently Treated Operatively: A 6-Year Epidemiological Study in two University Hospitals in Finland Treatment of Pediatric Tibia Shaft Fractures

BACKGROUND

Internal fixation of pediatric tibia shaft fractures has become increasingly popular despite the fact that non-operative treatment results in satisfactory outcome with few exceptions. Indications for surgery and benefits of internal fixation are however still debatable.

MATERIALS AND METHODS

All 296 less than 16-year-old patients treated for a tibia shaft fracture between 2010 and 2015 in two of the five university hospitals in Finland were included in the study. Patient data were analyzed in three treatment groups: cast immobilization in emergency department, manipulation under anesthesia, and operative treatment. Incidence of operative treatment of pediatric tibia shaft fractures was calculated in the cities of Helsinki and Kuopio.

RESULTS

A total of 143 (47.3%) children's tibia shaft fractures were treated with casting in emergency department, 71 (22.3%) with manipulation under anesthesia, and 82 (30.4%) with surgery. Mean age of the patients in these treatment groups was 6.2, 8.7, and 12.7 years. Fibula was intact in 89%, 51%, and 27% of the patients, respectively. All 6 patients with multiple fractures and 16 of 18 patients with open fractures were treated operatively. In eight patients, primary non-operative treatment was converted to internal fixation. Operatively treated patients with isolated closed fractures were more likely to have a fibula fracture (46/66 vs 52/214, p < 0.001), be older in age (13.08 ± 2.4 vs 6.4 ± 3.7, p < 0.001), and have more primary angulation (6.9 ± 5.8 vs 0.48 ± 3.1, p < 0.001). Re-operations were done to eight and corrective osteotomy to two operatively treated children.

CONCLUSION

Operative treatment of a pediatric tibia shaft fracture is currently nearly a rule in patients with open or multiple fractures. Surgical treatment of closed tibia shaft fractures is based on surgeon's personal preference, type of fracture and age of the patient.

Free amino acids and 5'-nucleotides in Finnish forest mushrooms

Edible mushrooms are valued because of their umami taste and good nutritional values. Free amino acids, 5'-nucleotides and nucleosides were analyzed from four Nordic forest mushroom species (Lactarius camphoratus, Boletus edulis, Cantharellus cibarius, Craterellus tubaeformis) using high precision liquid chromatography analysis. To our knowledge, these taste components were studied for the first time from Craterellus tubaeformis and Lactarius camphoratus. The focus was on the umami amino acids and 5'-nucleotides. The free amino acid and 5'-nucleotide/nucleoside contents of studied species differed from each other. In all studied samples, umami amino acids were among five major free amino acids. The highest concentration of umami amino acids was on L. camphoratus whereas B. edulis had the highest content of sweet amino acids and C. cibarius had the highest content of bitter amino acids. The content of umami enhancing 5'-nucleotides were low in all studied species.

Multimodal Nonlinear Optical Imaging for Sensitive Detection of Multiple Pharmaceutical Solid-State Forms and Surface Transformations

Two nonlinear imaging modalities, coherent anti-Stokes Raman scattering (CARS) and sum-frequency generation (SFG), were successfully combined for sensitive multimodal imaging of multiple solid-state forms and their changes on drug tablet surfaces. Two imaging approaches were used and compared: (i) hyperspectral CARS combined with principal component analysis (PCA) and SFG imaging and (ii) simultaneous narrowband CARS and SFG imaging. Three different solid-state forms of indomethacin-the crystalline gamma and alpha forms, as well as the amorphous form-were clearly distinguished using both approaches. Simultaneous narrowband CARS and SFG imaging was faster, but hyperspectral CARS and SFG imaging has the potential to be applied to a wider variety of more complex samples. These methodologies were further used to follow crystallization of indomethacin on tablet surfaces under two storage conditions: 30 °C/23% RH and 30 °C/75% RH. Imaging with (sub)micron resolution showed that the approach allowed detection of very early stage surface crystallization. The surfaces progressively crystallized to predominantly (but not exclusively) the gamma form at lower humidity and the alpha form at higher humidity. Overall, this study suggests that multimodal nonlinear imaging is a highly sensitive, solid-state (and chemically) specific, rapid, and versatile imaging technique for understanding and hence controlling (surface) solid-state forms and their complex changes in pharmaceuticals.

Nanofibrillar cellulose-alginate hydrogel coated surgical sutures as cell-carrier systems

Hydrogel nanomaterials, especially those that are of non-human and non-animal origins, have great potential in biomedical and pharmaceutical sciences due to their versatility and inherent soft-tissue like properties. With the ability to simulate native tissue function, hydrogels are potentially well suited for cellular therapy applications. In this study, we have fabricated nanofibrillar cellulose-alginate (NFCA) suture coatings as biomedical devices to help overcome some of the limitations related to cellular therapy, such as low cell survivability and distribution out of target tissue. The addition of sodium alginate 8% (w/v) increased the NFCA hydrogel viscosity, storage and loss moduli by slightly under one order of magnitude, thus contributing significantly to coating strength. Confocal microscopy showed nearly 100% cell viability throughout the 2-week incubation period within and on the surface of the coating. Additionally, typical morphologies in the dual cell culture of spheroid forming HepG2 and monolayer type SK-HEP-1 were observed. Twelve out of 14 NFCA coated surgical sutures remained intact during the suturing operation with various mice and rat tissue; however, partial peeling off was observed in 2 of the coated sutures. We conclude that NFCA suture coatings could perform as cell-carrier systems for cellular based therapy and post-surgical treatment.

Carry-over effects of conditions at the wintering grounds on breeding plumage signals in a migratory bird: roles of phenotypic plasticity and selection

To understand the consequences of ever-changing environment on the dynamics of phenotypic traits, distinguishing between selection processes and individual plasticity is crucial. We examined individual consistency/plasticity in several male secondary sexual traits expressed during the breeding season (white wing and forehead patch size, UV reflectance of white wing patch and dorsal melanin coloration) in a migratory pied flycatcher (Ficedula hypoleuca) population over an 11-year period. Furthermore, we studied carry-over effects of three environmental variables (NAO, a climatic index; NDVI, a vegetation index; and rainfall) at the wintering grounds (during prebreeding moult) on the expression of these breeding plumage traits of pied flycatcher males at individual and population levels. Whereas NAO correlates negatively with moisture in West Africa, NDVI correlates positively with primary production. Forehead patch size and melanin coloration were highly consistent within individuals among years, whereas the consistency of the other two traits was moderate. Wing patch size decreased with higher NAO and increased with higher rainfall and NDVI at the individual level. Interestingly, small-patched males suffered lower survival during high NAO winters than large-patched males, and vice versa during low NAO winters. These counteracting processes meant that the individual-level change was masked at the population level where no relationship was found. Our results provide a good example of how variation in the phenotypic composition of a natural population can be a result of both environment-dependent individual plasticity and short-term microevolution. Moreover, when plasticity and viability selection operate simultaneously, their impacts on population composition may not be evident.

Photothermally Triggered Lipid Bilayer Phase Transition and Drug Release from Gold Nanorod and Indocyanine Green Encapsulated Liposomes

In light-activated liposomal drug delivery systems (DDSs), the light sensitivity can be obtained by a photothermal agent that converts light energy into heat. Excess heat increases the drug permeability of the lipid bilayer, and drug is released as a result. In this work, two near-IR responsive photothermal agents in a model drug delivery system are studied: either gold nanorods (GNRs) encapsulated inside the liposomes or indocyanine green (ICG) embedded into the lipid bilayer. The liposome system is exposed to light, and the heating effect is studied with fluorescent thermometers: laurdan and CdSe quantum dots (QDs). Both photothermal agents are shown to convert light into heat in an extent to cause a phase transition in the surrounding lipid bilayer. This phase transition is also proven with laurdan generalized polarization (GP). In addition to the heating results, we show that the model drug (calcein) is released from the liposomal cavity with both photothermal agents when the light power is sufficient to cause a phase transition in the lipid bilayer.

Single exosome study reveals subpopulations distributed among cell lines with variability related to membrane content

Current analysis of exosomes focuses primarily on bulk analysis, where exosome-to-exosome variability cannot be assessed. In this study, we used Raman spectroscopy to study the chemical composition of single exosomes. We measured spectra of individual exosomes from 8 cell lines. Cell-line-averaged spectra varied considerably, reflecting the variation in total exosomal protein, lipid, genetic, and cytosolic content. Unexpectedly, single exosomes isolated from the same cell type also exhibited high spectral variability. Subsequent spectral analysis revealed clustering of single exosomes into 4 distinct groups that were not cell-line specific. Each group contained exosomes from multiple cell lines, and most cell lines had exosomes in multiple groups. The differences between these groups are related to chemical differences primarily due to differing membrane composition. Through a principal components analysis, we identified that the major sources of spectral variation among the exosomes were in cholesterol content, relative expression of phospholipids to cholesterol, and surface protein expression. For example, exosomes derived from cancerous versus non-cancerous cell lines can be largely separated based on their relative expression of cholesterol and phospholipids. We are the first to indicate that exosome subpopulations are shared among cell types, suggesting distributed exosome functionality. The origins of these differences are likely related to the specific role of extracellular vesicle subpopulations in both normal cell function and carcinogenesis, and they may provide diagnostic potential at the single exosome level.

Fluorescence-suppressed time-resolved Raman spectroscopy of pharmaceuticals using complementary metal-oxide semiconductor (CMOS) single-photon avalanche diode (SPAD) detector

In this work, we utilize a short-wavelength, 532-nm picosecond pulsed laser coupled with a time-gated complementary metal-oxide semiconductor (CMOS) single-photon avalanche diode (SPAD) detector to acquire Raman spectra of several drugs of interest. With this approach, we are able to reveal previously unseen Raman features and suppress the fluorescence background of these drugs. Compared to traditional Raman setups, the present time-resolved technique has two major improvements. First, it is possible to overcome the strong fluorescence background that usually interferes with the much weaker Raman spectra. Second, using the high photon energy excitation light source, we are able to generate a stronger Raman signal compared to traditional instruments. In addition, observations in the time domain can be performed, thus enabling new capabilities in the field of Raman and fluorescence spectroscopy. With this system, we demonstrate for the first time the possibility of recording fluorescence-suppressed Raman spectra of solid, amorphous and crystalline, and non-photoluminescent and photoluminescent drugs such as caffeine, ranitidine hydrochloride, and indomethacin (amorphous and crystalline forms). The raw data acquired by utilizing only the picosecond pulsed laser and a CMOS SPAD detector could be used for identifying the compounds directly without any data processing. Moreover, to validate the accuracy of this time-resolved technique, we present density functional theory (DFT) calculations for a widely used gastric acid inhibitor, ranitidine hydrochloride. The obtained time-resolved Raman peaks were identified based on the calculations and existing literature. Raman spectra using non-time-resolved setups with continuous-wave 785- and 532-nm excitation lasers were used as reference data. Overall, this demonstration of time-resolved Raman and fluorescence measurements with a CMOS SPAD detector shows promise in diverse areas, including fundamental chemical research, the pharmaceutical setting, process analytical technology (PAT), and the life sciences.

Graphical abstract

Sympatric divergence and clinal variation in multiple coloration traits of Ficedula flycatchers

Geographic variation in phenotypes plays a key role in fundamental evolutionary processes such as local adaptation, population differentiation and speciation, but the selective forces behind it are rarely known. We found support for the hypothesis that geographic variation in plumage traits of the pied flycatcher Ficedula hypoleuca is explained by character displacement with the collared flycatcher Ficedula albicollis in the contact zone. The plumage traits of the pied flycatcher differed strongly from the more conspicuous collared flycatcher in a sympatric area but increased in conspicuousness with increasing distance to there. Phenotypic differentiation (PST ) was higher than that in neutral genetic markers (FST ), and the effect of geographic distance remained when statistically controlling for neutral genetic differentiation. This suggests that a cline created by character displacement and gene flow explains phenotypic variation across the distribution of this species. The different plumage traits of the pied flycatcher are strongly to moderately correlated, indicating that they evolve non-independently from each other. The flycatchers provide an example of plumage patterns diverging in two species that differ in several aspects of appearance. The divergence in sympatry and convergence in allopatry in these birds provide a possibility to study the evolutionary mechanisms behind the highly divergent avian plumage patterns.

Solid formulations by a nanocrystal approach: critical process parameters regarding scale-ability of nanocrystals for tableting applications

Nanocrystallization is among the foremost drug delivery platform approaches for the commercial development of poorly soluble drugs. There exists an urge to enable a universal shift of the production of the solid nanocrystal formulations from laboratory scale to industrially feasible scale. The success of any formulation development depends on its transferability to large scale manufacture. The objectives of the study were to increase the nanocrystallization batch size and to screen and optimize parameters for industrially feasible itraconazole (ITC) and indomethacin (IND) nanocrystal composition for tablet formulation. Thus, ITC and IND were transformed into nanocrystal suspensions, using an increased batch size of a wet milling process, freeze-dried, and further developed into both direct compression (DC) and granulated (G) tableting masses. According to the investigated powder and tablet properties (true density, flowability, dose uniformity, maximum upper punch force, crushing strength, dissolution and disintegration) and stability testings, it was clear that the amount of the nanocrystals in the solid tablet formulation is critical in order to fully utilize the benefits of the nanocrystals, i.e., fast dissolution, and to produce high-quality tablets. The DC designs of both the model drugs with compositions including 40% of freeze-dried nanocrystalline drug powder outperformed the corresponding granulated tablets in all parameters after the stability surveillance.

Nanocrystal-based per-oral itraconazole delivery: superior in vitro dissolution enhancement versus Sporanox® is not realized in in vivo drug absorption

Nanoscience holds true promise in enabling efficient formulation development and in vivo delivery of poorly water soluble drugs. The objective of this study was to formulate solid oral nanocrystal delivery systems of itraconazole, and thus enhance the oral bioavailability of the very poorly soluble drug. Nanocrystal suspensions were prepared by a rapid wet milling technique, after which the suspensions were transformed into solid dosage forms by both freeze drying and granulating. Finally, the obtained nanocrystalline powders were capsule-packed as well as compacted to tablets. After in vitro analysis, the formulations (nanocrystal suspension (NPs), freeze dried NPs, granulated NPs) were tested in vivo in a rat model, and compared with commercial itraconazole formulation (Sporanox). Importantly, the results indicated rapid dissolution of the nanocrystalline itraconazole with enhanced bioavailability compared to physical mixture. Drug dissolution in vitro was immediate from NPs and freeze dried powder, and differed significantly from the marketed product (P=0.004 and 0.002, correspondingly) until 30min. Freeze drying was detected to be especially advantageous for the solid dosage forms. It is possible to maintain the original character of the nanocrystals, e.g. rapid dissolution, even after tableting of the nanocrystalline powders. Interestingly, the marketed product out-performed the nanocrystalline formulations in vivo, even though the nanocrystals provided reasonable bioavailability of itraconazole absorption as well. The efficient in vitro dissolution enhancement of the nanocrystalline formulations compared to Sporanox® was not realized in in vivo drug absorption.