Polymer Swelling Research Articles

Study on the performance and sustainability of modified waste crumb rubber and steel slag powder/SBS composite modified asphalt mastic

This study proposes the incorporation of waste steel slag and waste rubber into asphalt to prepare asphalt mastic with increased mechanical properties and can thus concurrently limit environmental pollution from these wastes. The surface of crumb rubber (CR) was activated by NaClO and was then treated with KH550 silane coupling modifier. Dynamic shear rheometer (DSR), multi-stress creep recovery (MSCR) and zero shear viscosity (ZSV) tests were applied explore the high temperature performance of asphalt mastic. The performance of asphalt mastic was analyzed by Burgers model, and the enhancement mechanism was analyzed by Fourier transform infra-red (FTIR) spectroscopy, scanning electron microscopy (SEM), energy dispersive X-ray (EDX), fluorescent microscopy (FM), and X-ray diffraction (XRD). Experimental results showed that coupling modified CR improved the complex modulus (G*) and rutting factor (G*/sinδ) and reduced the temperature sensitivity of asphalt mastic. The coupling modified CR increased the elasticity coefficient E1, viscosity coefficient η1, relaxation time η1/E1 and delay time η2/E2 of asphalt mastic by 2.8 times, 3.6 times, 1.3 times and 0.9 times, respectively, while steel slag powder (SSP) further enhanced the mechanical properties of the asphalt mastic. FM test showed that coupling modifier CR promoted the swelling of CR and SBS polymer, and hence resulted in a well-developed cross-linked network structure in the asphalt. The positive effect of SSP on the high temperature properties of asphalt mastic suggests that the use of SSP and CR in pavement engineering provides a sustainable solution for the disposal of industrial wastes and the preparation of new asphalt mastic with higher mechanical and thermal properties for practical applications.

Impact of polymer crosslinking on release mechanisms from long-acting levonorgestrel intrauterine systems

Polydimethylsiloxane (PDMS) crosslinking density is a critical material attribute of levonorgestrel intrauterine systems (LNG-IUSs) that affects drug release and may have a significant influence on product performance and safety. Accordingly, the objective of the present work was to investigate the impact of PDMS crosslinking on the release mechanisms of LNG-IUSs and thereby achieve better product understanding. To investigate the effect of PDMS crosslinking, LNG-IUSs with varying prepolymer ratios and different mixing conditions were prepared. Accelerated and real-time in vitro release of the LNG-IUSs were conducted for up to 80 days and 7 months, respectively. Contrary to conventional understanding, formulations with higher crosslinking density showed faster drug release rates. To further understand this anomalous release behavior, the microstructure and molecular properties (using scanning electron microscopy, mercury intrusion porosimetry, polymer swelling studies, solid-state silicon NMR, and wide-angle X-ray diffraction) were investigated. Interestingly, it was revealed that high PDMS crosslinking forms a solid-state porous branched network with amorphous polymer domains facilitating fast solvent uptake (in organic solvents) and easy access to the drug particles leading to rapid mass transport of the drug molecules. Furthermore, formulations processed using planetary mixing showed higher crosslinking densities and faster drug release rates than those prepared using manual mixing. Model fitting of all LNG-IUSs were carried out using first order, two-phase (zero order plus Higuchi), and Korsmeyer-Peppas models. The first order model (which showed the best fitting for the full release profile) was used to establish correlations between the drug release rates and the PDMS crosslinking densities of LNG-IUSs. This is the first comprehensive report providing novel insights into crosslinking-induced microstructural changes and physicochemical properties that dictate drug release from LNG-IUSs.

Impact of prolonged water‐gas flow on the performance of polyacrylamide

AbstractExcessive water production from natural reservoirs is a major challenge in oil and gas industry. Relative permeability modifiers (RPM) are used to selectively reduce water production with minimum effect on the hydrocarbon production. This work examined the performance of polyacrylamide in terms of its water control efficiency at prolonged water‐gas flowing cycles. During each cycle, as the volume of injected water increased, the RPM demonstrated stronger performance in terms of reducing water permeability. This is attributed to the swelling of polymer layer adsorbed to the pore surfaces. Conversely, during each cycle, higher volume of gas injection led to less reduction in the gas effective permeability (PRg) which is due to polymer shrinkage. The reduction in water absolute permeability (PRw) of the treated micromodel in each injection cycle was significantly greater than the reduction in gas permeability. Interestingly, as water‐gas cycles progressed, a significant increase in water permeability reduction was observed. It is also found that polymer expansion and shrinkage are reversible. As such, the RPM performance depends on the injected fluid, injected fluid volumes and water‐gas injecting cycling. We thus conclude that that polymer swelling, and shrinkage and polymer‐gas interaction play a vital role in RPM performance.

Impact of Swelling of Spray Dried Dispersions in Dissolution Media on their Dissolution: An Investigation Based on UV Imaging

Impact of SDD-dissolution medium interactions on the swelling and dissolution of spray dried dispersions (SDDs) was investigated using UV imaging by monitoring SDD swelling in situ, along with correlating of the swelling with the micro-dissolution and intrinsic dissolution of SDDs. SDDs of ketoconazole or indomethacin with three polymers: polyvinylpyrrolidone (PVP), hydroxypropyl cellulose (HPC), and hydroxypropyl methylcellulose acetate succinate (HPMC-AS) were prepared for the study. Dissolution media employed for assessing swelling and dissolution include water, acetate buffer, phosphate buffer, fasted state simulated intestinal fluid (FaSSIF), and fed state simulated intestinal fluid (FeSSIF), in which influence of polymers and drugs together with the physical-chemical properties of dissolution media (pH, and the presence of sodium taurocholate and lecithin) on SDD swelling and dissolution was evaluated. It appears that hydrophilic and hydrophobic properties of polymers can significantly impact SDD swelling and thus the dissolution. Furthermore, properties of dissolution media such as pH as well as presence of bile salts and lecithin seems to affect SDD swelling and dissolution as well. Throughout the text, thermodynamic swelling of polymers was used to interpret SDD dissolution behavior. Finally, practical implication of polymer swelling on dissolution was discussed.

Scalable Flexible Phase Change Materials with a Swollen Polymer Network Structure for Thermal Energy Storage

3D porous structural materials are proved to be enticing candidates for the fabrication of high-performance organic phase change materials (PCMs), but the stringent fabrication process and poor processability greatly hampered their commercialization. Herein, flexible leakage-proof composite PCMs with pronounced comprehensive performance are fabricated by a scalable polymer swelling strategy without using any solvent, in which the paraffin wax (PW) segment is confined in a robust flexible 3D polymer network, giving rise to the composite PCMs with excellent form stability even at 160 °C, a high latent heat energy storage density of 133.6 J/g, and an outstanding thermal conductivity of up to ∼5.11 W/mK. More importantly, the mass production of the flexible composite phase change fiber, film, and bulk products can be achieved by adopting mature processing technologies. These resultant composite PCMs exhibit promising thermal management ability to solve the overheating problem of electronics and high-efficiency solar-thermal energy conversion capacity.

Water-induced polymer swelling and its application in soft electronics

Polymer blend system has been commonly applied in a wide variety of applications. Herein, we propose to introduce sugar particles to polymer matrix, which results in a controllable polymer swelling under the action of osmotic pressure upon soaking in water. Taking advantage of this economic and environment-friendly, water-induced polymer swelling process, we have fabricated wrinkled conductive films and 3D structures by depositing conductive materials on the swollen polymer substrates for stretchable strain sensing devices. Several commercial silicone elastomers were utilized in the study. Key processing factors affecting the polymer swelling were investigated, including film thickness, sugar concentration, and temperature of soaking medium. The swelling ratio can be regulated by changing these parameters and the soaking duration. By sputtering gold (Au) on the swollen films (through vapor deposition) or depositing graphene on 3D complex structures companied by polymer swelling (in aqueous dispersion), wrinkled conductive elastomer films and 3D structures have been fabricated. These conductors not only demonstrated high sensitivity in electrical response when subjected to external deformations from 5% up to 100%, but also possessed good stability after long-term stretching/releasing cycles. The excellent electrical properties of these elastomer conductors implied a great potential in applications of flexible and stretchable sensors.

Halloysite/cellulose derivatives‐based bionanocomposites for controlled naproxen delivery

AbstractBionanocomposites are biocompatible, biodegradable, low‐toxicity materials inorganic/biopolymer‐based, carrying drugs for controlled delivery. The development of novel materials aiming to improve drug efficacy and reduce its toxicity is a continuous focus of the pharmaceutical industry. In this work, we report the development of an innovative controlled naproxen delivery system. The bionanocomposites are composed of naproxen‐loaded halloysite and ethylcellulose/hydroxypropylmethylcellulose blends produced by the spray drying technique. Chemical modification in the halloysite nanotubes was performed, aiming to improve the ionic interactions with the naproxen. The bionanocomposites drug‐load efficiency and interactions were characterized by physicochemical analysis. We also evaluated the naproxen release and its transport mechanism. Results show an efficient drug loading into halloysite, varying from 70% to 90%. Moreover, the naproxen release was delayed up to four times (compared with raw naproxen), that is, 48 h from nanotubes by Fickian diffusion, and sustained for 60 h from (bio)nanocomposites. The naproxen release from bionanocomposites occurred by several processes as diffusion, polymer swelling, and erosion. Furthermore, no drug was released at simulated gastric fluid, which may reduce the undesirable gastrointestinal effects. The developed bionanocomposites are potential for clinical applications for controlled drug delivery, as naproxen, a nonsteroidal anti‐inflammatory, commonly prescribes chronic disease treatment.

Preparation and Characterization of pH-Independent Sustained-Release Tablets Containing Hot Melt Extruded Solid Dispersions of Clarithromycin : Tablets Containing Solid Dispersions of Clarithromycin.

The limited solubility of clarithromycin (CAM), coupled with low bioavailability and rapid elimination, are major shortcomings, needed to be addressed to achieve optimum therapeutic goals. Therefore, sustained-release (SR) tablets containing solid dispersion (SD) granules of CAM were prepared in this study. Initially, SD granules of CAM were prepared by hot melt extrusion (HME) technique using Kollidon VA64 as a hydrophilic carrier. The saturation solubility of SD showed almost 4.5-fold increase as compared to pure CAM in pH 6.8 medium. In vitro drug dissolution data indicated a substantial increase in the dissolution of SD as compared to that of pure CAM. The thermal stability of drug, carrier, and SD at elevated HME temperatures was evident from the results of thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Powder X-ray diffraction (PXRD) data and scanning electron microscope (SEM) images revealed a decrease in the crystallinity and the uniform dispersion of drug, respectively. Moreover, Fourier transformed infrared spectroscopy (FT-IR) data confirmed the formation of hydrogen bond between the carbonyl group of drug and the hydroxyl group of carrier. SD loaded sustained-release (SD-SR) matrix tablets were prepared with hydrophobic polymers (Eudragit RS100 and Eudragit RL100). The pH-independent swelling and permeability of both polymers were responsible for the sustained drug release from SD-SR tablets. Pharmacokinetic (PK) studies suggested a 3.4-fold increase in the relative bioavailability of SD-SR tablets as compared to that of pure CAM.

Quaternary Holey Carbon Nanohorns/SnO2/ZnO/PVP Nano-Hybrid as Sensing Element for Resistive-Type Humidity Sensor

In this study, a resistive humidity sensor for moisture detection at room temperature is presented. The thin film proposed as a critical sensing element is based on a quaternary hybrid nanocomposite CNHox//SnO2/ZnO/PVP (oxidated carbon nanohorns–tin oxide–zinc oxide–polyvinylpyrrolidone) at the w/w/w/w ratios of 1.5/1/1/1 and 3/1/1/1. The sensing structure consists of a Si/SiO2 dielectric substrate and interdigitated transducers (IDT) electrodes, while the sensing film layer is deposited through the drop-casting method. Morphology and composition of the sensing layers were investigated through scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX), X-ray diffraction, and Raman spectroscopy. Each quaternary hybrid nanocomposite-based thin film’s relative humidity (RH) sensing capability was analyzed by applying a direct current with known intensity between two electrodes and measuring the voltage difference when varying the RH from 0% to 100% in a humid nitrogen atmosphere. While the sensor with CNHox/SnO2/ZnO/PVP at 1.5/1/1/1 as the sensing layer has the better performance in terms of sensitivity, the structure employing CNHox//SnO2/ ZnO/PVP at 3/1/1/1 (mass ratio) as the sensing layer has a better performance in terms of linearity. The contribution of each component of the quaternary hybrid nanocomposites to the sensing performance is discussed in relation to their physical and chemical properties. Several alternative sensing mechanisms were taken into consideration and discussed. Based on the measured sensing results, we presume that the impact of the p-type semiconductor behavior of CNHox, in conjunction with the swelling of the hydrophilic polymer, is dominant and leads to the overall increasing resistance of the sensing film.

Fabrication of highly crosslinked and monodispersed silicon-containing polymeric microspheres via photo-initiated polymerization and their application in capillary liquid chromatography

Although inorganic silica-based and polymeric micron-sized spheres have widely been explored as column packing materials in high performance liquid chromatography (HPLC), they are still suffering the problems of either alkali corrosion of silica or polymer swelling. It is still necessary to search simple approaches for fabrication of monodisperse micron-sized hybrid particles as packing materials in HPLC. A novel kind of silicon-containing polyacrylate microspheres was designed and fabricated via two-step swelling and photo-initiated polymerization approach using 3-(allylpropylsilane) propyl acrylate (TAPA) containing both acrylate and vinyl groups and trimethylolpropane triacrylate (TRIM) as precursors. After carefully optimizing the fabrication conditions, the monodisperse micron-sized microspheres could be acquired as chromatographic packing, exhibiting excellent mechanical stability and reproducibility. Due to existence of electron-rich vinyl groups, three kinds of thiols such as octadecanethiol (ODT), dithiothreitol (DTT) and trimethylolpropane tris(3-mercaptopropionate) (TTMP) were facilely anchored onto the surface of microsphere via photo-initiated thiol-ene click reaction. They were applied in the separation of small molecules by cLC-UV and complex biosamples by cLC-MS/MS. A total of 6691 unique peptides from 1771 unique proteins was identified by ODT-modified microsphere, which was higher than those by unmodified and DTT/TTMP-modified poly(TAPA-co-TRIM) microspheres. It was expected this kind of hybrid microspheres can be further modified and widely applied in chromatographic field, offering great potential in commercialization.

Core-Shell Fluorescent Polymeric Particles with Tunable White Light Emission Based on Aggregation Microenvironment Manipulation.

White-light emitting polymers (WLEPs) based on aggregation microenvironment-sensitive aggregation-induced emission (AIE) and Förster resonance energy transfer (FRET) have aroused great interest in lighting and optoelectronic devices. Herein, we developed a novel strategy to construct WLEP particles via a stepwise self-stabilized precipitation polymerization of two emission-complementary AIEgens under core-shell engineering, where the AIE characteristics and FRET process of core-shell fluorescent polymeric particles (CS-FPPs) could be modulated by altering aggregation microenvironment under swelling and shrinking of polymers, facilitating the tunable white light emission of CS-FPPs. Furthermore, such tuning could be fast realized in the solid state, thus demonstrating the potential in anti-counterfeiting. This work proved the significance of aggregation microenvironment on emission of luminogens, guiding the development of high-efficiency emission-tunable materials.

Core–Shell Fluorescent Polymeric Particles with Tunable White Light Emission Based on Aggregation Microenvironment Manipulation

AbstractWhite‐light emitting polymers (WLEPs) based on aggregation microenvironment‐sensitive aggregation‐induced emission (AIE) and Förster resonance energy transfer (FRET) have aroused great interest in lighting and optoelectronic devices. Herein, we developed a novel strategy to construct WLEP particles via a stepwise self‐stabilized precipitation polymerization of two emission‐complementary AIEgens under core–shell engineering, where the AIE characteristics and FRET process of core–shell fluorescent polymeric particles (CS‐FPPs) could be modulated by altering aggregation microenvironment under swelling and shrinking of polymers, facilitating the tunable white light emission of CS‐FPPs. Furthermore, such tuning could be fast realized in the solid state, thus demonstrating the potential in anti‐counterfeiting. This work proved the significance of aggregation microenvironment on emission of luminogens, guiding the development of high‐efficiency emission‐tunable materials.

Protic Ionic Liquid Based 3D Printable Ionogels for Applications As Electrolytes

When disregarding the current COVID19 crisis the climate change is one of the most pressing global issues with its well-known challenges concerning the energy economy and climate policy. In this context due to their many benefits, fuel cells and batteries are being discussed as potential applications. These technologies are not without some disadvantages themselves, though. Most polymer electrolyte membrane (PEM) fuel cells work with Nafion®, a sulfonated fluorocopolymer, as their membrane, which loses conductivity at higher temperatures due to dehydration, which limits the operation temperature to around 80 °C at ambient pressure. [1] As a result alternative membrane materials are needed which can preferably be designed with defined geometries and sizes and show high ion mobilities and corresponding ionic conductivities at elevated temperatures.As promising components in energy devices such as fuel or solar cells and batteries ionic liquids (ILs) are discussed due to their promising properties. These salts with melting points below 100 °C show high thermal and electrochemical stability, non-flammability and high ionic conductivities. For the applications mentioned above the immobilization of the ILs is necessary to realize proper function and prevent leaking. [2] The immobilization of the ILs can be realized in three different ways: 1. swelling of polymers in the IL, 2. polymerization of polymerizable ILs and 3. polymerization of vinyl-monomers in an IL. [3] The resulting ionogels (IGs) can then combine for example the characteristics of the respective IL with the useful properties of the polymer, i.e. its mechanical stability. To realize precise shapes and geometries for the membrane materials stereolithography and 3D-printing of the respective IGs provide a suitable method. [4]The aim of this study is the synthesis and characterization of ILs for proton-conduction. The ionic conductivities of these compounds range between 10-2 - 10-4 S/cm at elevated temperatures. Moreover, these ILs exhibit wide electrochemical (e. g. ΔE up to 3 V) and thermal stability windows (Td ≥ 230 °C) and are therefore promising for ion transport at elevated temperatures. NMR-studies also provide information about their ion mobility. Furthermore the ILs are immobilized via two of the aforementioned methods to provide flexible and transparent IGs that contain up to 80 wt% of IL. These IGs display promising thermal and mechanical stability and reach ionic conductivities of up to 10-3 S/cm at elevated temperatures. Successful 3D-printing and therefore structuring of IGs can also be demonstrated.[1] Martinez, et al., Journal of Power Sources, 2010, 195, 5829–5839.[2] Le Bideau, L. Viau, A. Vioux, Chem. Soc. Rev., 2011, 40, 907–925.[3] Lu, F. Yan, J. Texter, Progress in Polymer Science, 2009, 34, 431-448.[4] Zehbe, A. Lange, A. Taubert, Energy Fuels, 2019, 33, 12885-12893.

Synthesis and Characterization of N-Isopropylacrylamide Microspheres as pH Sensors.

Swellable polymer microspheres that respond to pH were prepared by free radical dispersion polymerization using N-isopropylacrylamide (NIPA), N,N′-methylenebisacrylamide (MBA), 2,2-dimethoxy-2-phenylacetylphenone, N-tert-butylacrylamide (NTBA), and a pH-sensitive functional comonomer (acrylic acid, methacrylic acid, ethacrylic acid, or propacrylic acid). The diameter of the microspheres was between 0.5 and 1.0 μm. These microspheres were cast into hydrogel membranes prepared by mixing the pH-sensitive swellable polymer particles with aqueous polyvinyl alcohol (PVA) solutions followed by crosslinking with glutaric dialdehyde for use as pH sensors. Large changes in the turbidity of the PVA membrane were observed as the pH of the buffer solution in contact with the membrane was varied. These changes were monitored by UV–visible absorbance spectroscopy. Polymer swelling of many NIPA copolymers was reversible and independent of the ionic strength of the buffer solution in contact with the membrane. Both the degree of swelling and the apparent pKa of the polymer microspheres increased with temperature. Furthermore, the apparent pKa of the polymer particles could be tuned to respond sharply to pH in a broad range (pH 4.0–7.0) by varying the amount of crosslinker (MBA) and transition temperature modifier (NTBA), and the amount, pKa, and hydrophobicity of the pH-sensitive functional comonomer (alkyl acrylic acid) used in the formulation. Potential applications of these polymer particles include fiber optic pH sensing where the pH-sensitive material can be immobilized on the distol end of an optical fiber.

NOVEL FLOATING AGENT SACCHAROMYCES BOULARDII FORMULATION BASED FLOATING DRUG DELIVERY SYSTEM

Objective: The objective is to design and optimize a floating tablet of furosemide using a novel floating agent Saccharomyces boulardii. Methods: In this study floating tablet based on principle of combination of floating and swelling prepared by direct compression technique. Saccharomyces boulardii probiotics preparation is used as a floating agent due to its bloating property i.e. production of CO2 gas and hydrophilic polymer HPMC E LV 15 used as swellable polymer. Furosemide is a BCS class IV drug selected as model drug which shows pH dependent solubility and permeability and it is better absorbed from the gastric region, hence to improve dissolution and residence at absorption site of such drug, floating drug delivery system is needed. Calcium hydroxide used as pH modifier which increase rate of dissolution of furosemide and also maintain integrity of tablet matrix. Formulation designed and developed using central composite design response surface methodology technique, so as to explore the effect of formulation variables such as amount of Saccharomyces boulardii preparation and calcium hydroxide on floating lag time and % drug release after 12h. Results: The numerical and graphical optimization technique were used to choose the optimal formulation. Floating lag time was found to be 12.6 min and 88.18% drug release for the optimized formulation. In vivo buoyancy studies depicted that formulation stay more then 6h in stomach. Conclusion: Study indicate that Saccharomyces boulardii is a promising floating agent, and the formulation containing this novel floating agent is suitable for gastro retention and it increases bioavailability of furosemide.

Microstructure and performance of epoxy asphalt binders modified by core-shell rubbers containing different core polymers

Core-shell rubber (CSR) is a good candidate for toughening epoxy asphalt binders. However, the knowledge of the effect of the core polymer on the performance of CSR modified hot-mix epoxy asphalt binder (HEAB) is not completed and systematic yet. In this paper, CSR modified HEABs were prepared by the incorporation of 2 wt% CSR particles with different core polymers, which were in turn subjected to viscous measurements, confocal microscopy, thermogravimetric analysis, dynamic mechanical analysis and tensile tests. The results revealed that the viscosity of CSR with styrene-butadiene copolymer (SB) core (CSRSB) modified HEAB is higher than that of CSR with polybutadiene (PB) core (CSRPB) modified HEAB during curing. The shell destruction of CSR particles resulted in the swelling of the core polymers and dispersion of swollen core polymer particles in the epoxy phase in the micron scale along with asphalt particles. The phase separation of CSRPB modified HEAB occurred in the spinodal decomposition mode, which was different from the nucleation and growth mechanism of the neat and CSRSB modified HEABs. The area fraction of swollen PB particles in the CSR modified HEAB was greater than that of swollen SB particles. The core polymer had a negligible effect on the thermal stability of CSR modified HEABs. The glass transition temperatures of epoxy and asphalt, damping ability and mechanical properties of the neat HEAB were increased with the addition of CSR particles. Especially, CSRPB modified HEAB had higher tensile strength and toughness than CSRSB modified HEAB. With 2 wt% CSRPB particles being adding, the tensile strength, elongation at break and toughness of the neat HEAB were increased by 53%, 42% and 110%, respectively.

Determination of the migration of plastic additives and non-intentionally added substances into food simulants and the assessment of health risks from convenience food packaging

Convenience foods are currently popular among busy, modern consumers. However, the migration of plastics additives and non-intentionally added substances (NIAS) from packaging materials has raised concern about the potential health risks. The migration of nine compounds, including additives (butylated hydroxytoluene and 2,2,4-trimethyl-1,3-pentanediol diisobutyrate), and NIAS that originated from additives degradation products (phenol, 2-ethyl-1-hexanol, acetophenone, 4-propylbenzaldehyde, 2,6-di-tert-butylbenzoquinone, 2,4-di-tert-butylphenol, and methyl-3-(3,5-ditertbutyl-4-hydroxyphenyl)) from convenience food packaging was evaluated in migration tests employing food simulants under real-life consumption and worst-case scenario conditions. Their migration level in the food simulants was quantified by gas chromatography-mass spectrometry. Most of the compounds had a low frequency of detection and the detected compounds varied depending on the individual samples, regardless of the packaging materials. The worst-case migration tests showed that repetitive microwave heating considerably accelerated the migration and degradation of the additives due to polymer swelling, although a single microwave heating had little effect on the migration. Risk assessment confirmed that the current level of exposure of Korean consumers to the substances from convenience food packaging is unlikely to pose a health risk, even in the worst-case scenario.

Toward High Spatially Resolved Proteomics Using Expansion Microscopy.

Expansion microscopy (EM) is an emerging approach for morphological examination of biological specimens at nanoscale resolution using conventional optical microscopy. To achieve physical separation of cell structures, tissues are embedded in a swellable polymer and expanded several fold in an isotropic manner. This work shows the development and optimization of physical tissue expansion as a new method for spatially resolved large-scale proteomics. Herein we established a novel method to enlarge the tissue section to be compatible with manual microdissection on regions of interest and MS-based proteomic analysis. A major issue in expansion microscopy is the loss of protein information during the mechanical homogenization phase due to the use of proteinase K. For isotropic expansion, different homogenization agents were investigated, both to maximize protein identification and to minimize protein diffusion. Best results were obtained with SDS for homogenization. Using our modified protocol, we were able to enlarge a tissue section more than 3-fold and identified up to 655 proteins from 1 mm in size after expansion, equivalent to 330 μm in their real size corresponding thus to an average of 260 cells. This approach can be performed easily without any expensive sampling instrument. We demonstrated the compatibility of sample preparation for expansion microscopy and proteomic study in a spatial context.

Swellable microneedles based transdermal drug delivery: Mathematical model development and numerical experiments

Recently, swellable microneedles (SMNs) have gained significant interest due to their potential applications in transdermal drug delivery (TDD). SMNs swell by absorbing interstitial fluid in the skin, and they facilitate drug transport into the skin without polymer dissolution. To establish the SMNs for practical usages, one requires an accurate understanding of the drug transport mechanisms from these MNs that would allow both controlled TDD as well as optimisation of the MN geometries. In addressing this issue, a mathematical model is formulated which incorporates the key parameters defining the skin properties and physicochemical properties of the MNs, such as the polymer swelling capacity, mechanical deformation, amount of drug loading, and penetration depth in the skin. Numerical simulations are performed using well-defined MN parameters which represent the MN constituent and drug, namely, polyvinyl alcohol and insulin, in this study. The proposed mathematical model predicts that insulin diffuses into the blood to reach a maximum concentration of 11.72 ng/ml in 1.5 h, and ~95% insulin is eliminated from the blood within 11 h. The rate of insulin diffusion to blood increases with an increase in MN swelling. However, not much difference is observed in the insulin profiles when MNs swell more than two times their mass as the skin tends to displace the MN out of the skin, as it increases the length of the diffusion pathway for the drug in the skin layers. The depth of MN penetration affects the overall insulin delivery, with insulin getting eliminated from the body in 8 h when MN is fully inserted into the skin. The rate of change of blood concentration of insulin is found to increase and decrease non-linearly with time for the cases studied in this paper. The developed model provides a platform for optimization of SMNs for the controlled delivery of different drug molecules.

Super-absorbent swellable polymer as grouting material for treatment of karst water inrush

Grouting is the most commonly used method to control water inrush in underground engineering. Traditional cement-based materials are easy to dilute and hard to coagulate under the influence of large flow and high-velocity water inrush. To address these deficiencies, a new type of polymer grouting material with an excellent expansion ratio was synthesised. The material quickly absorbs water and has an expansion ratio of 1:300. The material is composed of a superabsorbent polymer (SAP), glycerol, and ethanol. The effects of water quality on the expansion ratio and expansion rate of the material were examined, and the best solid–liquid ratio for the slurry was determined by fluidity measurements. A karst specially designed pipeline water inrush test device showed that 800 g of SAP can achieve 0.6 m/s water flow blockage in the smooth pipeline, demonstrating that the ability of the SAP slurry to block water inrush is superior to those of other materials. This study provides a reference for water inrush plugging, and has important implications for the reduction and control of karst pipeline-type water inrush disasters, ensuring the safety of construction sites and preventing loss of life and damage to property.