A surface-independent bioglue using photo-crosslinkable benzophenone moiety.

Surface coating technology is broadly demanded across various fields, including marine and biomedical materials; therefore, a facile and versatile approach is desired. This study proposed an attractive surface coating strategy using photo-crosslinkable benzophenone (BP) moiety for biomaterials application. BP-containing "bioglue" polymer can effectively crosslink with all kinds of surfaces and biomolecules. Upon exposure to ultraviolet (UV) light, free radical reaction from the BP glue facilitates the immobilization of diverse molecules onto different substrates in a straightforward and user-friendly manner. Through either one-step, mixing the bioglue with targeted biomolecules, or two-step methods, pre-coating the bioglue and then adding targeted biomolecules, polyacrylic acid (PAA), cyclic RGD-containing peptides, and proteins (gelatin, collagen, and fibronectin) were successfully immobilized on substrates. After drying the bioglue, targeted biomolecules can still be immobilized on the surfaces preserving their bioactivity. Cell culture on biomolecule-immobilized surfaces using NIH 3T3 fibroblasts and human bone marrow stem cells (hBMSCs) showed significant improvement of cell adhesion and activity compared to the unmodified control in serum-free media after 24 hours. Furthermore, hBMSCs on the fibronectin-immobilized surface showed an increased calcium deposition after 21 days of osteogenic differentiation, suggesting that the immobilized fibronectin is highly bioactive. Given the straightforward protocol and substrate-independent bioglue, the proposed coating strategy is promising in broad-range fields.

Insights into Targeted and Stimulus-Responsive Nanocarriers for Brain Cancer Treatment.

Brain cancers, especially glioblastoma multiforme, are associated with poor prognosis due to the limited efficacy of current therapies. Nanomedicine has emerged as a versatile technology to treat various diseases, including cancers, and has played an indispensable role in combatting the COVID-19 pandemic as evidenced by the role that lipid nanocarrier-based vaccines have played. The tunability of nanocarrier physicochemical properties -including size, shape, surface chemistry, and drug release kinetics- has resulted in the development of a wide range of nanocarriers for brain cancer treatment. These nanocarriers can improve the pharmacokinetics of drugs, increase blood-brain barrier transfer efficiency, and specifically target brain cancer cells. These unique features would potentially allow for more efficient treatment of brain cancer with fewer side effects and better therapeutic outcomes. This review provides an overview of brain cancers, current therapeutic options, and challenges to efficient brain cancer treatment. The latest advances in nanomedicine strategies are investigated with an emphasis on targeted and stimulus-responsive nanocarriers and their potential for clinical translation.

Oral nanotherapeutic formulation of insulin with reduced episodes of hypoglycaemia.

Injectable insulin is an extensively used medication with potential life-threatening hypoglycaemic events. Here we report on insulin-conjugated silver sulfide quantum dots coated with a chitosan/glucose polymer to produce a responsive oral insulin nanoformulation. This formulation is pH responsive, is insoluble in acidic environments and shows increased absorption in human duodenum explants and Caenorhabditis elegans at neutral pH. The formulation is sensitive to glucosidase enzymes to trigger insulin release. It is found that the formulation distributes to the liver in mice and rats after oral administration and promotes a dose-dependent reduction in blood glucose without promoting hypoglycaemia or weight gain in diabetic rodents. Non-diabetic baboons also show a dose-dependent reduction in blood glucose. No biochemical or haematological toxicity or adverse events were observed in mice, rats and non-human primates. The formulation demonstrates the potential to orally control blood glucose without hypoglycaemic episodes.

Influence of Surface Ligand Density and Particle Size on the Penetration of the Blood-Brain Barrier by Porous Silicon Nanoparticles.

Overcoming the blood-brain barrier (BBB) remains a significant challenge with regard to drug delivery to the brain. By incorporating targeting ligands, and by carefully adjusting particle sizes, nanocarriers can be customized to improve drug delivery. Among these targeting ligands, transferrin stands out due to the high expression level of its receptor (i.e., transferrin receptor) on the BBB. Porous silicon nanoparticles (pSiNPs) are a promising drug nanocarrier to the brain due to their biodegradability, biocompatibility, and exceptional drug-loading capacity. However, an in-depth understanding of the optimal nanoparticle size and transferrin surface density, in order to maximize BBB penetration, is still lacking. To address this gap, a diverse library of pSiNPs was synthesized using bifunctional poly(ethylene glycol) linkers with methoxy or/and carboxyl terminal groups. These variations allowed us to explore different transferrin surface densities in addition to particle sizes. The effects of these parameters on the cellular association, uptake, and transcytosis in immortalized human brain microvascular endothelial cells (hCMEC/D3) were investigated using multiple in vitro systems of increasing degrees of complexity. These systems included the following: a 2D cell culture, a static Transwell model, and a dynamic BBB-on-a-chip model. Our results revealed the significant impact of both the ligand surface density and size of pSiNPs on their ability to penetrate the BBB, wherein intermediate-level transferrin densities and smaller pSiNPs exhibited the highest BBB transportation efficiency in vitro. Moreover, notable discrepancies emerged between the tested in vitro assays, further emphasizing the necessity of using more physiologically relevant assays, such as a microfluidic BBB-on-a-chip model, for nanocarrier testing and evaluation.

Fluoropolymer Functionalization of Organ-on-Chip Platform Increases Detection Sensitivity for Cannabinoids.

Microfluidic technology is applied across various research areas including organ-on-chip (OOC) systems. The main material used for microfluidics is polydimethylsiloxane (PDMS), a silicone elastomer material that is biocompatible, transparent, and easy to use for OOC systems with well-defined microstructures. However, PDMS-based OOC systems can absorb hydrophobic and small molecules, making it difficult and erroneous to make quantitative analytical assessments for such compounds. In this paper, we explore the use of a synthetic fluoropolymer, poly(4,5-difluoro-2,2-bis(trifluoromethyl)-1,3-dioxole-co-tetrafluoroethylene) (Teflon™ AF 2400), with excellent "non-stick" properties to functionalize OOC systems. Cannabinoids, including cannabidiol (CBD), are classes of hydrophobic compounds with a great potential for the treatment of anxiety, depression, pain, and cancer. By using CBD as a testing compound, we examined and systematically quantified CBD absorption into PDMS by means of an LC-MS/MS analysis. In comparison to the unmodified PDMS microchannels, an increase of approximately 30× in the CBD signal was detected with the fluoropolymer surface modification after 3 h of static incubation. Under perfusion conditions, we observed an increase of nearly 15× in the CBD signals from the surface-modified microchannels than from the unmodified microchannels. Furthermore, we also demonstrated that fluoropolymer-modified microchannels are compatible for culturing hCMEC/D3 endothelial cells and for CBD perfusion experiments.

Recent Advances in Formulations for Long-Acting Delivery of Therapeutic Peptides.

Recent preclinical and clinical studies have focused on the active area of therapeutic peptides due to their high potency, selectivity, and specificity in treating a broad range of diseases. However, therapeutic peptides suffer from multiple disadvantages, such as limited oral bioavailability, short half-life, rapid clearance from the body, and susceptibility to physiological conditions (e.g., acidic pH and enzymolysis). Therefore, high peptide dosages and dose frequencies are required for effective patient treatment. Recent innovations in pharmaceutical formulations have substantially improved therapeutic peptide administration by providing the following advantages: long-acting delivery, precise dose administration, retention of biological activity, and improvement of patient compliance. This review discusses therapeutic peptides and challenges in their delivery and explores recent peptide delivery formulations, including micro/nanoparticles (based on lipids, polymers, porous silicon, silica, and stimuli-responsive materials), (stimuli-responsive) hydrogels, particle/hydrogel composites, and (natural or synthetic) scaffolds. This review further covers the applications of these formulations for prolonged delivery and sustained release of therapeutic peptides and their impact on peptide bioactivity, loading efficiency, and (in vitro/in vivo) release parameters.

The potential impact of nanomedicine on COVID-19-induced thrombosis.

Extensive reports of pulmonary embolisms, ischaemic stroke and myocardial infarctions caused by coronavirus disease 2019 (COVID-19), as well as a significantly increased long-term risk of cardiovascular diseases in COVID-19 survivors, have highlighted severe deficiencies in our understanding of thromboinflammation and the need for new therapeutic options. Due to the complexity of the immunothrombosis pathophysiology, the efficacy of treatment with conventional anti-thrombotic medication is questioned. Thrombolytics do appear efficacious, but are hindered by severe bleeding risks, limiting their use. Nanomedicine can have profound impact in this context, protecting delicate (bio)pharmaceuticals from degradation en route and enabling delivery in a targeted and on demand manner. We provide an overview of the most promising nanocarrier systems and design strategies that may be adapted to develop nanomedicine for COVID-19-induced thromboinflammation, including dual-therapeutic approaches with antiviral and immunosuppressants. Resultant targeted and side-effect-free treatment may aid greatly in the fight against the ongoing COVID-19 pandemic.

Wearable microneedle array-based sensor for transdermal monitoring of pH levels in interstitial fluid.

Microneedle-based wearable sensors offer an alternative approach to traditional invasive blood-based health monitoring and disease diagnostics techniques. Instead of blood, microneedle-based sensors target the skin interstitial fluid (ISF), in which the biomarker type and concentration profile resemble the one found in the blood. However, unlike blood, interstitial fluid does not have the same pH-buffering capacity causing deviation of pH levels from the physiological range. Information about the skin ISF pH levels can be used as a biomarker for a wide range of pathophysiological conditions and as a marker for the calibration of a wearable sensor. The ISF pH can significantly affect the detection accuracy of other biomarkers as it influences enzyme activity, aptamer affinity, and antibody-antigen interaction. Herein, we report the fabrication of a high-density polymeric microneedle array-based (PMNA) sensing patch and its optimization for the potentiometric transdermal monitoring of pH levels in ISF. The wearable sensor utilizes a polyaniline-coated PMNA having a density of ∼10,000 microneedles per cm2, containing individual microneedles with a height of ∼250 µm, and a tip diameter of ∼2 µm. To prevent interference from other body fluids like sweat, an insulating layer is deposited at the base of the PMNA. The wearable pH sensor operates from pH 4.0 to 8.6 with a sensitivity of 62.9 mV per pH unit and an accuracy of ±0.036 pH units. Furthermore, testing on a mouse demonstrates the ability of the PMNA to provide a real-time reading of the transdermal pH values. This microneedle-based system will significantly contribute to advancing transdermal wearable sensors technology, simplifying the fabrication process, and improving the cost-effectiveness of such devices.

Differential Surface Engineering Generates Core-Shell Porous Silicon Nanoparticles for Controlled and Targeted Delivery of an Anticancer Drug.

An approach to differentially modify the internal surface of porous silicon nanoparticles (pSiNPs) with hydrophobic dodecene and the external surface with antifouling poly-N-(2-hydroxypropyl) acrylamide (polyHPAm) as well as a cell-targeting peptide was developed. Specifically, to generate these core-shell pSiNPs, the interior surface of a porous silicon (pSi) film was hydrosilylated with 1-dodecene, followed by ultrasonication to create pSiNPs. The new external surfaces were modified by silanization with a polymerization initiator, and surface-initiated atom transfer radical polymerization was performed to introduce polyHPAm brushes. Afterward, a fraction of the polymer side chain hydroxyl groups was activated to conjugate cRGDfK─a peptide with a high affinity and selectivity for the ανß3 integrin receptor that is overexpressed in prostate and melanoma cancers. Finally, camptothecin, a hydrophobic anti-cancer drug, was successfully loaded into the pores. This drug delivery system showed excellent colloidal stability in a cell culture medium, and the in vitro drug release kinetics could be fine-tuned by the combination of internal and external surface modifications. In vitro studies by confocal microscopy and flow cytometry revealed improved cellular association attributed to cRGDfK. Furthermore, the cell viability results showed that the drug-loaded and peptide-functionalized nanoparticles had enhanced cytotoxicity toward a C4-2B prostate carcinoma cell line in both 2D cell culture and a 3D spheroid model.

Theranostic nanoparticles for the management of thrombosis.

Acute thrombosis and thromboembolisms are one of the leading causes of mortality and morbidity in both developed and developing countries, placing a huge burden on health and economic systems. Early diagnosis is critical but currently limited in accuracy and hampered by a narrow time frame, where the short therapeutic window also severely restricts treatment options. Additionally, clinically used antithrombotics and thrombolytics suffer from severe side effects and are limited in efficacy by a short half-life and susceptibility to degradation. The use of systems containing both diagnostic and therapeutic moieties, known as theranostics, can potentially improve patient outcomes by increasing the precision and efficacy of diagnosis and treatment, enabling personalised and precision medicine. Leveraging nanomedicine may further improve treatment by improving the system's pharmacokinetic properties including controlled drug delivery. This review provides an overview of the development of such theranostic nanoparticle systems, with a focus on approaches that may be utilised to usher this field towards clinical use.

Ionic Liquid-Based Low-Temperature Synthesis of Crystalline Ti(OH)OF·0.66H2O: Elucidating the Molecular Reaction Steps by NMR Spectroscopy and Theoretical Studies.

We present an in-depth mechanistic study of the first steps of the solution-based synthesis of the peculiar hexagonal tungsten bronze-type Ti(OH)OF·0.66H2O solid, using NMR analyses (1H, 13C, 19F, and 11B) as well as modeling based on density functional theory (DFT) and ab initio molecular dynamics (AIMD) simulation. The reaction uses an imidazolium-based ionic liquid (IL, e.g., C x mim BF4) as a solvent and reaction partner. It is puzzling, as the fluorine-rich crystalline solid is obtained in a "beaker chemistry" procedure, starting from simple compounds forming a stable solution (BF4 --containing IL, TiCl4, H2O) at room temperature, and a remarkably low reaction temperature (95 °C) is sufficient. Building on NMR experiments and modeling, we are able to provide a consistent explanation of the peculiar features of the synthesis: evidently, the hydrolysis of the IL anion BF4 - is a crucial step since the latter provides fluoride anions, which are incorporated into the crystal structure. Contrary to expectations, BF4 - does not hydrolyze in water at room temperature but interacts with TiCl4, possibly forming a TiCl4 complex with one or two coordinated BF4 - units. This interaction also prevents the heavy hydrolysis reaction of TiCl4 with H2O but-on the other side-spurs the hydrolysis of BF4 - already at room temperature, releasing fluoride and building F-containing Ti(OH) x Cl4-x F y complexes. The possible complexes formed were analyzed using DFT calculations with suitable functionals and basis sets. We show in addition that these complexes are also formed using other titanium precursors. As a further major finding, the heating step (95 °C) is only needed for the condensation of the Ti(OH) x Cl4-x F y complexes to form the desired solid product but not for the hydrolysis of BF4 -. Our study provides ample justification to state a "special IL effect", as the liquid state, together with a stable solution, the ionic nature, and the resulting deactivation of H2O are key requirements for this synthesis.

Silicon Micropillar Array-Based Wearable Sweat Glucose Sensor.

Wearable technologies have great potential in health monitoring and disease diagnostics. As a consequence, interest in the study of wearable sensors has dramatically increased over recent years. Successful translation of this technology from research prototypes to commercial products requires addressing some of the major challenges faced by wearable sensors such as loss of, and damage in, the biological recognition layer of the skin-interfaced sensors. In this work, we propose a solution to this challenge by integrating micropillar array (MPA) surfaces as part of the sensing layer with the aim to protect and prevent the loss of the enzyme layer from mechanical stress while the sensor is worn. The proposed wearable sensing patch is composed of reference, counter, and working electrodes, all made of MPAs and is designed for measuring glucose in sweat. MPA sensing patch has a wide linear range of 50 µM to 1.4 mM, a sensitivity of 4.7 ± 0.8 µA mM-1, and a limit of detection of 26 ± 5 µM. The glucose sensing patch was tested using human sweat where glucose-level changes were successfully measured before and after meal consumption. The developed patch provides an alternative solution to the problem of the damage to the sensor microenvironment upon wear. But in addition, it also offers a user-friendly, cost-effective, and reliable sweat analysis platform with significant potential in health monitoring applications.

Development of Polymeric Nanoparticles for Blood-Brain Barrier Transfer-Strategies and Challenges.

Neurological disorders such as Alzheimer's disease, stroke, and brain cancers are difficult to treat with current drugs as their delivery efficacy to the brain is severely hampered by the presence of the blood-brain barrier (BBB). Drug delivery systems have been extensively explored in recent decades aiming to circumvent this barrier. In particular, polymeric nanoparticles have shown enormous potentials owing to their unique properties, such as high tunability, ease of synthesis, and control over drug release profile. However, careful analysis of their performance in effective drug transport across the BBB should be performed using clinically relevant testing models. In this review, polymeric nanoparticle systems for drug delivery to the central nervous system are discussed with an emphasis on the effects of particle size, shape, and surface modifications on BBB penetration. Moreover, the authors critically analyze the current in vitro and in vivo models used to evaluate BBB penetration efficacy, including the latest developments in the BBB-on-a-chip models. Finally, the challenges and future perspectives for the development of polymeric nanoparticles to combat neurological disorders are discussed.

How is CO2 absorbed into a deep eutectic solvent?

Deep eutectic solvents show great potential as CO2 absorbents, which is highly desirable for the sustainable development of CO2 reduction and prevention of global climate changes. Ab initio molecular dynamics simulations in the isothermal-isobaric ensemble at pressures of 1 MPa and 5 MPa and at the corresponding experimental density are carried out to investigate the CO2 absorption in choline chloride: ethylene glycol deep eutectic solvent. Based on the structural analysis, there is a strong anion and hydrogen bond donor effect and a minor cation effect on CO2 solvation in the solvent. Instead of cooperation, a competition between the anion and the hydrogen bond donor (ethylene glycol) for the interaction with CO2 is indicated. While at a lower pressure, the ethylene glycol-CO2 interaction dominates, at a higher pressure, it is the chloride-CO2 interaction. Thus, it is possible to use the same advantages within the deep eutectic solvent as the CO2 absorbent as in ionic liquids, but in the hydrogen bond, a donor can be exploited.

TiCl4 Dissolved in Ionic Liquid Mixtures from ab Initio Molecular Dynamics Simulations.

To gain a deeper understanding of the TiCl4 solvation effects in multi-component ionic liquids, we performed ab initio molecular dynamics simulations of 1-butyl-3-methylimidazolium [C4C1Im]+, tetrafluoroborate [BF4]-, chloride [Cl]- both with and without water and titanium tetrachloride TiCl4. Complex interactions between cations and anions are observed in all investigated systems. By further addition of water and TiCl4 this complex interaction network is extended. Observations of the radial distribution functions and number integrals show that water and TiCl4 not only compete with each other to interact mainly with [Cl]-, which strongly influences the cation-[BF4]- interaction, but also interact with each other, which leads to the fact that in certain systems the cation-anion interaction is enhanced. Further investigations of the Voronoi polyhedra analysis have demonstrated that water has a greater impact on the nanosegregated system than TiCl4 which is also due to the fact of the shear amount of water relative to all other components and its higher mobility compared to TiCl4. Overall, the polar network of the IL mixture collapses by including water and TiCl4. In the case of [Cl]- chloride enters the water continuum, while [BF4]- remains largely unaffected, which deeply affects the interaction of the ionic liquid (IL) network.

Enhanced electrochemical sensing performance by insitu electrocopolymerization of pyrrole and thiophene-grafted chitosan.

Nowadays, there is increasing number of electrochemical biosensors which utilize chitosan (Ch); as an enzyme immobilization matrix, and conductive nanomaterials; as electron carriers improving sensitivity of the biosensor. However, the challenge these sensors face is the lack of uniform dispersion of nanomaterials throughout the Ch film, which can negatively affect analytical performance of the biosensor. In this study, we report the development of an enzyme immobilization matrix that displays enhanced electrochemical performance thanks to a novel conductive thin film prepared via in situ electrocopolymerization of pyrrole (Py) and thiophene-grafted chitosan (Th-Ch). This is a simple thin film preparation method that can help overcome aforementioned challenges by providing a uniformly distributed conductive layer on the electrode. We are also for the first time reporting the synthesis and characterization of Th-Ch, where grafted Th plays an essential role as a linking group between Ch and Py. The resulting conductive Ch-based thin film was modified with glucose oxidase (GOx) which served as a model enzyme. In situ electrocopolymerization of Py with Th-Ch resulted in a highly conductive thin film enabling approximately 40% higher sensitivity when compared to a Py-Ch composite. This new type of composite thin film is promising in biosensor technology due to its biocompatibility, the chemically and physically modifiable structure, as well as its electrical conductivity.

Porous silicon nanomaterials: recent advances in surface engineering for controlled drug-delivery applications.

Porous silicon (pSi) nanomaterials are increasingly attractive for biomedical applications due to their promising properties such as simple and feasible fabrication procedures, tunable morphology, versatile surface modification routes, biocompatibility and biodegradability. This review focuses on recent advances in surface modification of pSi for controlled drug delivery applications. A range of functionalization strategies and fabrication methods for pSi-polymer hybrids are summarized. Surface engineering solutions such as stimuli-responsive polymer grafting, stealth coatings and active targeting modifications are highlighted as examples to demonstrate what can be achieved. Finally, the current status of engineered pSi nanomaterials for in vivo applications is reviewed and future prospects and challenges in drug-delivery applications are discussed.

Functional Brush Poly(2-ethyl-2-oxazine)s: Synthesis by CROP and RAFT, Thermoresponsiveness and Grafting onto Iron Oxide Nanoparticles.

Brush polymers are highly functional polymeric materials combining the properties of different polymer classes and have found numerous applications, for example, in nanomedicine. Here, the synthesis of functional phosphonate-ester-bearing brush polymers based on poly(2-oxazine)s is reported through a combination of cationic ring-opening polymerization (CROP) of 2-ethyl-2-oxazine and reversible addition-fragmentation chain transfer (RAFT) polymerization. In this way, a small library of well-defined (D ≤ 1.17) poly(oligo(2-ethyl-2-oxazine) methacrylate) P(OEtOzMA)n brushes with tunable lower critical solution temperature (LCST) behavior and negligible cell toxicity is prepared. Upon deprotection, the phosphonic acid end-group of the P(OEtOzMA)n brush enables the successful grafting-onto iron oxide nanoparticles (IONPs). Colloidal stability of the particle suspension in combination with suitable magnetic resonance imaging (MRI) relaxivities demonstrates the potential of these particles for future applications as negative MRI contrast agents.

Bioconjugation and Fluorescence Labeling of Iron Oxide Nanoparticles Grafted with Bromomaleimide-Terminal Polymers.

Iron oxide nanoparticles have been widely applied in biomedical applications for their unique physical properties. Despite the relatively mature synthetic approaches for iron oxide nanoparticles, surface modification strategies for obtaining particles with satisfactory biofunctionality are still urgently needed to meet the challenge of nanomedicine. Herein, we report a surface modification and biofunctionalization strategy for iron oxide-based magnetic nanoparticles based on a dibromomaleimide (DBM)-terminated polymer with brushed polyethylene glycol (PEG) chains. PEG acrylate and phosphonate monomers, serving as antibiofouling and surface anchoring compartments for iron oxide nanoparticles, were incorporated utilizing a novel DBM containing reversible addition-fragmentation chain transfer (RAFT) agent. The particles prepared through this new surface architecture possessed high colloidal stability in a physiological buffer and the capacity of covalent conjugation with biomolecules for targeting. Cell tracking of the molecular probes was achieved concomitantly by exploiting DBM conjugation-induced fluorescence of the nanoparticles.

Hydrophilic Ionic Liquid Mixtures of Weakly and Strongly Coordinating Anions with and without Water.

With the aid of ab initio molecular dynamics simulations, we investigate an ionic liquid (IL) mixture composed of three components 1-butyl-3-methylimidazolium [C4C1Im]+, tetrafluoroborate [BF4]-, and chloride [Cl]- without and with water. In the pure IL mixture, we observe an already complex network of interactions between cations and anions, and addition of water to the system even extends the complexity. Observed number integrals show that the coordination number between cations and anions is reduced in the system with water compared to that in the pure system. Further studies show that the Coulombic network of the strongly coordinating anion [Cl]- is disturbed by water, while that of the weakly coordinating anion [BF4]- is not. These observations can also be confirmed by the Voronoi polyhedra analysis, which shows that the polar network of microheterogeneous IL collapses by the introduction of water. Hydrogen-acceptor interactions revealed that the [Cl]- anions are transferred from being situated in the IL to the water continuum, while [BF4]- is almost unperturbed; these effects mainly influence the interplay of the ionic liquid network.