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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]

Cellulose nanocrystals (CNCs) were produced directly from hemp agro-waste (HAW) using ammonium persulfate (APS) oxidation. Industrial hemp growth in the US has been accompanied with HAW production. While hemp has previously been shown as a source for CNCs, studies on CNCs from HAW (specifically hemp hurd) have not been reported on. Furthermore, studies on the mechanical characteristics of individual CNCs extracted using APS are lacking. Herein, the one-step oxidation treatment was followed by a purification step to remove impurities and hence to colloidally stabilize CNCs in aqueous suspensions, then analysis of the morphological and mechanical properties was performed. Purified and unpurified CNC samples were compared for potential differences in morphological and mechanical properties. Morphological analysis was performed using atomic force microscopy (AFM): purified CNCs had an average length of 183.1 ± 73.9 nm, unpurified CNCs had an average length of 202.0 ± 79.2, and both samples had an average diameter of 4 ± 2 nm. Mechanical analysis of individual CNCs using force-distance spectroscopy (FDS) suggested both samples had little differences with average values of Young's modulus 2.19 ± 0.15 GPa, maximum loading force of 6.29 ± 0.09 nN, and adhesion energy of 1.57 ± 1.12e-16 J. No statistical differences between purified and unpurified CNCs were found in Young's modulus and maximum loading forces measurements, suggesting the impurities had minimum impact on mechanical strength. These results highlight the potential for mechanical assessment of individual CNCs extracted using APS from HAW via FDS and the need for further exploration into the methodology of this type of mechanical analysis. [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]

Hyperbranched poly (phenylalanine-lysine) (HBPL) is obtained by phenylalanine and lysine and then mixed with Polyvinyl Alcohol (PVA) polymer to electrospin PVA/HBPL fluorescent nanofiber mats (FNM), which is an excellent sensing material for Cu2+ ions in aqueous solutions. In this work, the relationship between mechanical properties, fluorescent properties and the sensing for Cu2+ ions of PVA/HBPL FNM are investigated. PVA/HBPL FNM with different mass ratio of PVA and HBPL are characterized by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectra, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), fluorescence spectrum and tensile tester. To further improve the water solubility of PVA/HBPL FNM, thermally cross-linking (TCL)-PVA/HBPL FNM is fabricated. The results indicate that the neat PVA FNM couldn't emit fluorescence under any excitation wavelength, whereas the PVA/HBPL FNM emit blue fluorescence green fluorescence when the irradiation of the excitation wavelength is at 330–385 nm and 450–480 nm, respectively. The tensile strength and Young's modulus of PVA/HBPL FNM are 8.67 MPa and 342.92 MPa, respectively, which suggested 43.1% and 242.7% than that of neat PVA NM. Furthermore, the solubility rate of TCL-PVA/HBPL FNM is significantly decreased in comparison of FNM in absent of cross-linking. It's worth noting that TCL-PVA/HBPL FNM possessed higher recognition than other mental ions and could be used as metal ion detection sensor to combine with Cu2+. Moreover, it represented a linear relationship between the fluorescence intensity and the concentration of Cu2+ in the range of 5 µM to 100 µM. The fabricated TCL-PVA/HBPL FNM exhibit high mechanical and fluorescence properties, which make it be potentially envisaged for heavy metal ions detection sensor. [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]

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]