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Biomaterials to facilitate the restoration of cardiac tissue is of emerging importance. While there are many aspects to consider in the design of biomaterials, mechanical properties can be of particular importance in this dynamically remodeling tissue. This review focuses on one specific processing method, electrospinning, that is employed to generate materials with a fibrous microstructure that can be combined with material properties to achieve the desired mechanical behavior. Current methods used to fabricate mechanically relevant micro-/nanofibrous scaffolds, in vivo studies using these scaffolds as therapeutics, and common techniques to characterize the mechanical properties of the scaffolds are covered. We also discuss the discrepancies in the reported elastic modulus for physiological and pathological myocardium in the literature, as well as the emerging area of in vitro mechanobiology studies to investigate the mechanical regulation in cardiac tissue engineering. Lastly, future perspectives and recommendations are offered in order to enhance the understanding of cardiac mechanobiology and foster therapeutic development in myocardial regenerative medicine. [ABSTRACT FROM AUTHOR]

Understanding nanoparticle–surface adhesion is necessary to develop inert tracers for subsurface applications. Here we show that nanoparticles with neutral surface charge may make the best subsurface tracers, and that it may be possible to used SiO 2 nanoparticle retention to measure the fraction of solid surface that has positive charge. We show that silica nanoparticles dispersed in NaCl electrolyte solutions are increasingly retained in calcium carbonate (calcite) sand-packed columns as the solution ionic strength increases, but are not retained if they are injected in pure water or Na 2 SO 4 electrolyte solutions. The particles retained in the NaCl experiments are released when the column is flushed with pure water or Na 2 SO 4 solution. AFM measurements on calcite immersed in NaCl solutions show the initial repulsion of a silica colloidal probe as the surface is approached is reduced as the solution ionic strength increases, and that at high ionic strengths it disappears entirely and only attraction remains. These AFM measurements and their interpretation with Derjaguin–Landau–Verwey–Overbeek (DLVO) theory shows the calcite surface charge is always negative for Na 2 SO 4 solutions, but changes from negative to positive in a patchy fashion as the ionic strength of the NaCl solution increases. Since mixed-charge (patchy) surfaces may be common in the subsurface, nanoparticles with near-zero charge may make the best tracers. [ABSTRACT FROM AUTHOR]

This paper investigates delivery of encapsulated drug from poly lactic-co-glycolic micro-/nano-particles. Experimental data collected from about 50 papers are analyzed by machine learning algorithms including linear regression, principal component analysis, Gaussian process regression, and artificial neural networks. The focus is to understand the effect of drug solubility, drug molecular weight, particle size, and pH-value of the release matrix/environment on drug release profiles. The results obtained from machine learning is then used as guidelines for designing new in vitro experiments to examine dependence of drug release profiles on those four factors. It is interesting to see that indeed the results of the new in vitro experiments are in basic agreement with the results obtained from machine learning. [ABSTRACT FROM AUTHOR]

Poly(vinyl alcohol) (PVA) was modified using D‐mannitol (DM) and 1‐butyl‐3‐methylimidazole bromide (BMIMBr) as the complex plasticizer (DB), and PVA/DB composite was prepared. The plasticizing effect of DB on PVA was studied by Fourier transform infrared spectroscopy (FT‐IR), differntial scanning calorimetry (DSC), thermos gravimetric analysis (TGA) and melt flow indexer (MI). FT‐IR analysis indicated that Br− of BMIMBr and OH of DM could form H‐bonds with OH of PVA. With the increase of DB, the melt temperature (Tm2) and crystallization temperature (Tc1) of PVA/DB composite decreased, the initial thermal decomposition temperatures (Td), thermal processing window (ΔT) and MI values increased respectively. Based on above studies, the influence of DB content on rheological properties of PVA/DB composite was investigated by the capillary rheometer. The result displayed that apparent viscosity of PVA/DB composite decreased with increasing DB content, shear rate and measured temperature. The non‐Newtonian index (n) increased and structural viscosity index (Δη) decreased with the increase of measured temperature and DB. The viscous flow activation energy (Eη) decreased as the shear rate and DB content increased. When the measured temperature, DB content and shear rate were in the range of Tm2+30 −Tm2+35 °C, 40–50 wt% and 764.8–1504.9 s−1, respectively, the spinnability of PVA/DB composite was optimal, which will lay a theoretical foundation for the exploration of melt spinning process in the future. [ABSTRACT FROM AUTHOR]

Large-diameter polyvinyl alcohol (PVA) fiber has a broad application prospect in the field of reinforcing geomorphic building materials owing to its large diameter and excellent mechanical properties. In this work, PVA2499 polymer was used as the raw material, DMSO/H2O as the hybrid solvent, and the staged heating approach was adopted to obtain high solid content of spinning solutions, and then a series of large-diameter medium-strength PVA fibers with different solid contents of spinning solutions (SCS) were prepared by dry-wet spinning, and the Fourier transform infrared spectroscopy (FTIR), scan electron microscope (SEM), differential scanning calorimetry (DSC), thermal analysis (TGA), X-ray diffractometer (XRD) and electronic universal testing machine were performed to explore the effect of the SCS on the structure and performance of PVA fiber. The results displayed that with the increase of the SCS, the -OH stretching vibration absorption peak of PVA fiber moved from 3276 cm−1 to 3262 cm−1; The tensile strength, initial modulus, the crystallization and orientation of PVA fibers all increased first and then decreased. Especially, when the SCS was 23.5wt%, the diameter of the PVA fiber was 110.6 ± 6.0 μm (124.8 ± 6.2 dtex), the tensile strength was 7.0 ± 0.3 cN/dtex, the initial modulus was 106.2 ± 10.3 cN/dtex, the crystallization and the orientation were 49.6% and 96.8%, respectively. [ABSTRACT FROM AUTHOR]

High mechanical property poly (vinyl alcohol) (PVA) fibers have attracted tremendous attentions because of their excellent mechanical properties and has a potential application in the field of building enhancement. In this article, PVA polymer with high polymerization degree (Pn) and high Syndiotacticity-diad content (S-diad) were synthesized using vinyl acetate (VAc) and vinyl pivalate (VPi) as monomers via emulsion polymerization with water as solvent, the GPC and 1H NMR were used to characterized the Pn and S-diad of PVA polymer. Then the lanthanum chloride (LaCl3) was chosen as cross-linking and the synthesized PVA polymer as raw material for dry-wet spinning, a series of PVA fibers with high strength and high modulus have been prepared. The final PVA-La fibers were characterized through a series of experiments including of FTIR, SEM, DSC, TGA, XRD and fiber tensile tester. It turned out that the Pn and S-diad of synthesized PVA polymer were 4817 ± 76 and 56.3 ± 0.7%. With the increasing of LaCl3 content, the -OH vibration absorption peak of PVA-La composite fiber gradually increased from 3462 cm-1 to 3484 cm-1; the strength, modulus, crystallinity and orientation all increased first and then decreased. Especially, the properties of PVA-La fiber exhibited an optimal LaCl3 content of 0.8 wt%, the denier was 5.4 ± 0.5 dtex, the tensile strength and highest elastic modulus of 15.19 ± 0.5 cN/dtex and 369.21 ± 9.1cN/dtex, the elongation at break was 3.72 ± 0.4%, the crystallinity was 53.9 ± 0.6%, the orientation was 95.6 ± 0.6%. [ABSTRACT FROM AUTHOR]

Colorimetric biosensors made by polydiacetylene nanofibers have been of great interest in developing novel strategies of rapid and in situ detection to bacterial infection that is a major concern for human fatalities around the world. Previous studies have focused on bacterial detection and the sensitivity of the detection that the PDA biosensors can offer. However, the selectivity of the detection to different bacterial strains has not been well understood. With the recent emergence of multiple drug-resistance bacterial strains, selective detection of bacteria demands more attention and cutting-edge tools. In this study, a polydiacetylene (PDA) nanofiber biosensor prepared via electrospinning was found effectively to offer selective detection of Gram-negative bacteria such as Escherichia coli and Pseudomonas aeruginosa via a rapid blue-to-red colorimetric change. The quantification of the colorimetric changes suggested that the biosensor selectivity was effective in identifying with Gram-negative bacteria over Gram-positive bacteria (Staphylococcus aureus). The selectivity was likely due to structural differences between Gram-positive bacteria and Gram-negative bacteria such as cell outer layer thickness, as well as different extracellular polymeric substances (EPS) released by different bacteria. In addition, the nanofiber biosensor demonstrated superior antibacterial properties that were evaluated using bacteria staining and electron microscopic techniques. A comprehensive analysis of the interaction between the PDA nanofibers and different bacteria was presented to provide insightful understanding of selective detection and antibacterial properties of the PDA nanofibers. The results suggested that PDA nanofibers have great potential in medical textiles, personal protective equipment, and other biomedical applications. [ABSTRACT FROM AUTHOR]

In order to significantly enhance the fluorescence and mechanical properties of polyvinyl alcohol (PVA) fluorescent fibers, HBP(P-L) is synthesized by lysine, phenylalanine and N,N-methylene bisacrylamide via Michael addition reaction. Acidified multiwalled carbon nanotubes (MWCNTs) are added in HBP(P-L) solution, which are sonicated to obtain MWCNTs-HBP(P-L). Moreover, MWCNTs-HBP(P-L) is incorporated with PVA polymer to fabricate PVA fluorescence fibers via wet spinning. The fluorescence and mechanical properties of fabricated PVA fluorescence fibers are characterized by SEM, FTIR, XRD, DSC, fibers tensile tester and fluorescence spectroscopy. The results display that the neat PVA fibers could not emit fluorescence when emission peak is at 450–480 nm, while MWCNTs-HBP(P-L)/PVA fibers could emit green fluorescence. The neat PVA fibers still could not emit fluorescence when emission peak is at 530–550 nm, while MWCNTs-HBP(P-L)/PVA fibers could emit dark red fluorescence. Furthermore, the crystallinity, the degree of orientation, the breaking strength and modulus of MWCNTs-HBP(P-L)/PVA fibers are 65.0%, 93.8%, 6.52 cN/dtex and 76.33 cN/dtex, respectively. Especially, the breaking strength and modulus of MWCNTs-HBP(P-L)/PVA fibers are 15.2% and 82.1% higher than that of neat PVA fibers. The fabricated MWCNTs-HBP(P-L)/PVA fibers exhibit unique mechanical and fluorescence properties, which make it be potentially envisaged in biomedical application. [ABSTRACT FROM AUTHOR]

To address the challenge of enhancing the mechanical properties of polyvinyl alcohol (PVA) fiber, constrained by the spinning process limitations, this study introduces a PVA/DMSO spinning solution. The solution, with concentrations ranging from 21.0 wt%, utilized PVA polymer (DP of 7499 and S-diad of 53.7 %) as the raw material. This approach facilitated the production of high-strength and high-modulus PVA fibers through a consistent dry-wet spinning method. The viscosity of the spinning solution was determined using a viscometer, while the PVA fibers underwent comprehensive characterization through various testing methodologies. Fourier Transform Infrared (FTIR) spectroscopy analysis revealed an initial increase followed by a decrease in the hydrogen bonding within PVA fibers as the spinning solution concentration increased. Scanning Electron Microscope (SEM) imagery indicated that the surfaces of the PVA fibers were smooth. Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA), and X-Ray Diffraction (XRD) analyses demonstrated that the melting temperature, thermal decomposition temperature, and crystallinity of the PVA fibers exhibited a similar trend of initial increase and subsequent decrease with rising concentrations of the spinning solution. In addition, mechanical tester indicated that when spinning solution concentration was 22.5 wt% the PVA fibers process best mechanical property, and the breaking strength and elastic modulus reached 15.02 ± 0.5 cN/dtex and 357.12 ± 9.4 cN/dtex, respectively. [Display omitted] [ABSTRACT FROM AUTHOR]

Poly-lactic-co-glycolic acid (PLGA) was mixed with gentamicin sulfate via a double emulsion method, resulting in gentamicin-loaded PLGA nanoparticles that exhibited excellent antibacterial properties and great potential in fabricating smart wound dressings integrated with a drug delivery system. The nanoparticle morphologies, particle degradation rates, drug release profiles, and antibacterial properties were investigated using scanning electron microscopy (SEM), dynamic light scattering (DLS), ultraviolet–visible spectroscopy (UV–vis), and disk diffusion method. Nanoparticles prepared at different PLGA concentrations exhibited different release profiles that were determined by multiple release mechanisms including diffusion, osmotic pumping, and nanoparticle degradation. The antibacterial activities were measured using a disk diffusion method indicating that various nanoparticles loaded with antibiotics can control bacterial infection to some degree proving that nanoparticles used in this paper can be used in the pharmaceutical industry. The results suggested that drug release properties of gentamicin loaded PLGA nanoparticles can be affected by PLGA concentrations and PVA concentrations in the particle synthesis, providing a guidance in preparing gentamicin-loaded PLGA nanoparticles for topical antibiotics delivery applications. The nanoparticles with a spherical and uniformly porous structure were prepared with a PLGA concentration of 0.0167 g/ml and a PVA concentration of 12%, resulting in the highest average gentamicin release rate and excellent antibacterial activities. Four release mechanisms (diffusion through polymer, diffusion through pores, osmotic pumping, and nanoparticle degradation) primarily determined the gentamicin release process. [ABSTRACT FROM AUTHOR]

To address the shortcoming of Polyvinyl alcohol (PVA) fibers for food or medical packaging materials including low mechanical strength and poor water resistance, lignin (LN) was used as raw material, acetone/H 2 O as solvent to self-assemble into lignin nanoparticles (LNP) by adverse solvent precipitation approach, and then PVA/LNP composite fibers with different LNP contents were fabricated successfully by wet and dry spinning. Herein, vast hydrophilic hydroxyl groups in PVA decreased owing to the hydrogen bond between LN and PVA, Especially, with only 0.5 wt% loading of LNP into the PVA/LNP fibers, the diameter was 94.4 dtex, tensile strength was 10.1 cN/dtex (1279.8 MPa), initial modulus was 94.7 cN/dtex (12.0 GPa), the crystallinity was 56.7 %, the orientation was 97.1 %, and water contact angle was 103.1°. Compared with pure PVA fibers, the tensile strength of PVA/LNP-0.5 fibers was increased by 44.2 % and the contact angle was increased 37°. This work provides novel insights into obtaining lignin-reinforced PVA composite fibers with strong mechanical properties and excellent water resistance properties, indicating the potential of the PVA/LNP fibers for food or medical packaging application. [ABSTRACT FROM AUTHOR]

The polarity of asphaltenes influences production, transportation, and refining of heavy oils. However, the dipole moment of asphaltene molecules is difficult to measure due to their complex composition and electromagnetic opaqueness. In this work, we present a convenient and efficient way to determine the dipole moment of asphaltene in solution by dielectric measurements alone without measurement of the refractive index. The dipole moment of n-heptane asphaltenes of Middle East atmospheric residue (MEAR) and Ta–He atmospheric residue (THAR) are measured within the temperature range of −60 °C to 20 °C. There is one dielectric loss peak in the measured solutions of the two types of asphaltene at the temperatures of −60 °C or −40 °C, indicating there is one type of dipole in the solution. Furthermore, there are two dielectric loss peaks in the measured solutions of the two kinds of asphaltene when the temperature rises above −5 °C, indicating there are two types of dipoles corresponding to the two peaks. This phenomenon indicates that as the temperature increases above −5 °C, the asphaltene molecules aggregate and present larger dipole moment values. The dipole moments of MEAR C 7 -asphaltene aggregates are up to 5 times larger than those before aggregation. On the other hand, the dipole moments of the THAR C 7 -asphaltene aggregates are only 3 times larger than those before aggregation. It will be demonstrated that this method is capable of simultaneously measuring multi dipoles in one solution, instead of obtaining only the mean dipole moment. In addition, this method can be used with a wide range of concentrations and temperatures. [ABSTRACT FROM AUTHOR]