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Electroencephalography has garnered interest for applications in mobile healthcare, human-machine interfaces, and Internet of Things. Conventional electroencephalography relies on wet and dry electrodes. Despite favorable interface impedance of wet electrodes and skin, the application of a large amount of gel at their interface with skin limits the electroencephalography spatial resolution, increases the risk of shorting between electrodes, and makes them unsuited for long-term mobile recording. In contrast, dry electrodes are better suited for long-term recordings but susceptible to motion artifacts. In addition, both wet and dry electrodes are non-adhesive to the hairy scalp and mechanical support, or chemical adhesives are used to hold them in place. Herein, a conical microstructure array (CMSA) based sensor made of carbon nanotube-polydimethylsiloxane composite is reported. The CMSA sensor is fabricated using the innovative, cost-effective, and scalable method of viscosity-controlled dip-pull process. The sensor adheres to the hairy scalp by generating negative pressure in its conical microstructures when it is pressed against scalp. Aided by the application of a trace amount of gel, CMSA sensor establishes good electrical contact with the skin, enabling its applications in mobile electroencephalography over extended periods. Notably, the signal quality of CMSA sensors is comparable to that of medical-grade wet gel electrodes., (© 2023 The Authors. Advanced Healthcare Materials published by Wiley-VCH GmbH.)

Aliphatic polycarbonates (APCs) have been studied for decades but have not been as utilized as aliphatic polyesters in biomaterial applications such as drug delivery and tissue engineering. With the recognition that functionalized aliphatic polymers can be readily synthesized, increased attention is being paid to these materials. A frequently provided reason for utilizing these polymers is that they degrade to form diols and carbon dioxide. However, depending on the structure and molecular weight of the APC, degradation may not occur. In this review, the mechanisms by which APCs and functionalized APCs have been found to degrade in vivo are examined with the objective of providing guidance in the continued development of these polymers as biomaterials., (© 2021 Wiley-VCH GmbH.)

Azoxystrobin is the only synthetic, systemic fungicide labeled in the United States for management of frogeye leaf spot (FLS) of tobacco ( Nicotiana tabacum L.), caused by Cercospora nicotianae . Though traditionally considered a minor disease in the United States, FLS has recently become yield and quality limiting. In 2016 and 2017, 100 C. nicotianae isolates were collected from symptomatic tobacco from eight counties in Kentucky, United States. Prior to azoxystrobin sensitivity testing, some C. nicotianae isolates were found to utilize the alternative oxidase pathway and, after assay comparisons, conidial germination was utilized to evaluate sensitivity in C. nicotianae as opposed to mycelial growth. Azoxystrobin sensitivity was determined by establishing the effective concentration to inhibit 50% conidial germination (EC 50 ) for 47 (in 2016) and 53 (in 2017) C. nicotianae isolates. Distributions of C. nicotianae EC 50 values indicated three qualitative levels of sensitivity to azoxystrobin. Partial cytochrome b sequence, encompassing the F129L and G143A mutation sites, indicated single-nucleotide polymorphisms (SNPs) conferring the F129L mutation in C. nicotianae of moderate resistance (azoxystrobin at 0.177 ≤ EC 50 ≤ 0.535 µg/ml) and the G143A mutation in isolates with an azoxystrobin-resistant phenotype (azoxystrobin EC 50 > 1.15 µg/ml). Higher frequencies of resistant isolates were identified from greenhouse transplant (4 of 17) and conventionally produced (58 of 62) tobacco samples, as compared with field-grown tobacco (<4 weeks prior to harvest; 4 of 62) or organically produced samples (1 of 7), respectively. Together, these results suggest that resistance to azoxystrobin in C. nicotianae occurs broadly in Kentucky, and generate new hypotheses about selection pressure affecting resistance mutation frequencies.

Ligaments and tendons are comprised of aligned, crimped collagen fibrils that provide tissue-specific mechanical properties with non-linear extension behaviour, exhibiting low stress at initial strain (toe region behaviour). To approximate this behaviour, we report fibrous scaffolds with sinusoidal patterns by melt electrowriting (MEW) below the critical translation speed (CTS) by exploitation of the natural flow behaviour of the polymer melt. More specifically, we synthesised photopolymerizable poly(L-lactide-co-ε-caprolactone-co-acryloyl carbonate) (p(LLA-co-ε-CL-co-AC)) and poly(ε-caprolactone-co-acryloyl carbonate) (p(ε-CL-co-AC)) by ring-opening polymerization (ROP). Single fibre (fØ = 26.8 ± 1.9 µm) tensile testing revealed a customisable toe region with Young's Moduli ranging from E = 29 ± 17 MPa for the most crimped structures to E = 314 ± 157 MPa for straight fibres. This toe region extended to scaffolds containing multiple fibres, while the sinusoidal pattern could be influenced by printing speed. The synthesized polymers were cytocompatible and exhibited a tensile strength of σ = 26 ± 7 MPa after 10 4 cycles of preloading at 10% strain while retaining the distinct toe region commonly observed in native ligaments and tendon tissue., Statement of Significance: Damaged tendons and ligaments are serious and frequently occurring injuries worldwide. Recent therapies, including autologous grafts, still have severe disadvantages leading to a demand for synthetic alternatives. Materials envisioned to induce tendon and ligament regeneration should be degradable, cytocompatible and mimic the ultrastructural and mechanical properties of the native tissue. Specifically, we utilised photo-cross-linkable polymers for additive manufacturing (AM) with MEW. In this way, we were able to direct-write cytocompatible fibres of a few micrometres thickness into crimp-structured elastomer scaffolds that mimic the non-linear biomechanical behaviour of tendon and ligament tissue., (Copyright © 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.)

Growth factors represent an important therapeutic protein drug class, and would benefit significantly from formulations that provide sustained, local release to realize their full clinical potential. Biodegradable polymer-based delivery platforms have been examined to achieve this end; however, formulations based on conventional polymers have yet to yield a clinical product. This review examines new polymer biomaterials that have been developed for growth factor delivery. The dosage forms are discussed in terms of their mechanism of release, the stability of the released growth factor, their method of preparation, and their potential for clinical translation., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Polymerase chain reaction-based detection of plant-associated microbes depends on physical disruption of tissues of the host and microorganism in order to liberate nucleic acids during extraction. Using six types of plant tissues as well as an oospore preparation of Phytophthora capsici, we evaluated the use of pressure-cycling technology (PCT) compared with several common techniques for physical tissue disruption. With all tissues tested, bead-beating provided excellent yields of amplifiable nucleic acid, with a few inconsistent exceptions. The use of PCT did not consistently improve nucleic acid yields or "amplifiability". The use of a mortar and pestle to physically disrupt plant tissue also provided good results at low cost, though it was not consistently as effective as the bead-beater. Furthermore, handling of ground tissues in an open mortar may present more challenges in minimizing cross-contamination than working with tissues pulverized in a bead-beater tube.

Objective: Harvesting osteochondral grafts results in a zone of chondrocyte death (ZCD) in and around the periphery of the graft, creating a barrier for chondrocytes to migrate to the graft periphery, thus limiting cartilage-to-cartilage healing. The purpose of this study was to repopulate the induced ZCD through the combined effects of collagenase treatment and delivery of a chemotactic agent., Design: In bovine cartilage, the ZCD induced by the OATS™ osteochondral harvesting system was determined, followed by a corresponding collagenase treatment to penetrate the developed ZCD. The chemotactic potential of platelet derived growth factor (PDGF-bb), insulin-like growth factor I (IGF-I), and basic fibroblast growth factor (bFGF) (2.5-100 ng/mL) was then assessed using a modified Boyden chamber assay to select an appropriate agent to induce chondrocyte migration. Afterwards, the combined effects of collagenase treatment and chondrocyte chemotaxis on the repopulation of an induced ZCD were examined in cartilage explants over a 4-week-period., Results: The OATS™ osteochondral harvesting system induced a significant ZCD (173 μm, 95% CI: [72-274 μm]) in the grafts. Chondrocyte chemotaxis was induced by all agents investigated at concentrations greater than 25 ng/mL. After 4 weeks in culture, collagenase treatment alone reduced the ZCD by approximately 40% relative to untreated explants. Coupling the collagenase treatment with 25 ng/mL IGF-I reduced the ZCD by approximately 80% relative to untreated explants, and 65% relative to explants treated only with collagenase., Conclusion: Treating cartilage explants with collagenase and 25 ng/mL IGF-I resulted in a decreased ZCD after a 4-week-period, and increased chondrocyte density within the induced ZCD., (Copyright © 2010 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.)

A water-soluble, 19-mer peptide fragment of serum amyloid A called MFFD is being examined as a possible treatment for atherosclerosis. As a means of administering this drug in a sustained fashion through subcutaneous implantation, a biodegradable network formulation was prepared. The formulation consisted of 1000 and 4000Da alpha,omega-diacrylate oligo(d,l-lactide)-b-poly(ethylene glycol)-b-oligo(d,l-lactide) (DLPEGDLDA) copolymerized with 2700 and 5000Da omega,omega,omega-triacrylate star-poly(epsilon-caprolactone-co-d,l-lactide) using UV irradiation. The influence on the network properties and degradation rate of the network on the amount and type of DLPEGDLDA copolymerized with the two different molecular weight ASCPs were examined in vitro. The networks degraded by bulk hydrolysis at a rate controlled primarily by the molecular weight of the ASCP used. Nevertheless, all the networks were completely degraded within 16 weeks. The MFFD was released in a diffusional manner at a rate influenced by the degree of swelling of the network and the molecular weight of the ASCP used; using an ASCP of a lower molecular weight for a given DLPEGDLDA resulted in a slower release rate. The degree of swelling of the networks was controlled solely by the nature of the PEG used in preparing the DLPEGDLDA, with greater swelling observed with higher PEG molecular weight and for greater amounts of PEG incorporation. The MFFD was not degraded during the photocrosslinking reaction or by potential acidic degradation products that may have accumulated within the device. This formulation provides a means of achieving a desirable release rate from a degradable, water-swellable network through selection of ASCP molecular weight and DLPEGDLDA composition., (Copyright (c) 2009 Elsevier B.V. All rights reserved.)

A synthetic peptide fragment of human collagen type I (BCSP-1) was linked to the surface of a commercially available ceramic in an effort to improve the properties of the bone graft substitute to accelerate local healing. BCSP-1 was covalently immobilized on the surface of the ceramic via the linkers 3-aminopropyl-triethoxysilane (APTES) and suberic acid bis-N-hydroxysuccinimide ester (DSS). The chosen chemistry was non-cytotoxic. A rat calvaria cell assay using alkaline phosphatase (ALP) as an osteoblast differentiation marker, showed that modifying the surface of the ceramic was enough to enhance ALP activity, although the total cell population on the surface decreased. A significant increase in ALP activity/cell was noted with serum albumin bound to the surface, however, the BCSP-1 bound surface exhibited an even greater ALP activity that showed a surface concentration dependent trend. An optimal BCSP-1 surface density in the range of 0.87-2.24 nmol/cm2 elicited the maximum ALP activity/cell at day 6 of culture. The peptide bound ceramic generated an ALP activity/cell that was roughly 3-fold higher than the non-modified ceramic and 2-fold higher than the APTES-grafted ceramic.

Numerous peptide drugs require continuous and local delivery to obtain optimum therapeutic effect. Herein, we describe the incorporation of a model peptide drug, vitamin B12, as well as goserelin acetate, in biodegradable elastomer cylinders through photo-cross-linking. The elastomer was prepared from acrylated star-poly(epsilon-caprolactone-co-D,L-lactide). Release was manipulated through the incorporation of poly(ethylene glycol) diacrylate (PEGD) into the network at concentrations up to 30% (w/w). The PEGD in the network caused rapid swelling that remained constant throughout the release period. The degree of swelling was low, ranging from 10 to 45% (w/w), and increasing as the PEGD content increased. Release proceeded with a minimal initial burst, and extended periods of nearly constant release, ranging from approximately 5 to 70% mass fraction released, were obtained. The release rate was independent of particle size and increased as the cylinder diameter decreased, as the amount of PEGD increased, as the molecular weight of PEGD increased, and as the agent loading increased. Moreover, goserelin acetate, which has a comparable diffusivity but greater aqueous solubility, was released at a greater rate than vitamin B12. This release behavior is explained as a balance between agent dissolution in the swollen polymer matrix and diffusion through the polymer matrix bulk.

Biodegradable elastomers have a number of potential applications in the biomedical area, especially in the emerging field of soft-tissue engineering where the mechanical properties of the polymer scaffold should match those of the tissue to be grown. An increasing number of synthesis strategies have been employed in order to prepare such elastomers. In this review, these synthesis strategies and the properties of these elastomers are outlined. The factors that influence the characteristics of these elastomers including mechanical properties, degradation rate, and mechanical property change during degradation, are discussed in terms of the design of the elastomer and their advantages and disadvantages for the biomedical applications considered.

Previously, we prepared a biodegradable elastomeric device that can release different therapeutic proteins at a nearly constant rate in nanomolar concentrations with high bioactivity. The elastomer device was fabricated using a photo-initiated free radical cross-linking reaction of acrylated star(epsilon-caprolactone-co-D,L-lactide) in organic solvent in the presence of solid protein particles. The objective of this study was to examine the effect of various parameters used for fabricating the photo-cross-linked elastomeric device on the stability of a therapeutic protein, vascular endothelial growth factor (VEGF), to determine which factor plays the dominant role in protecting VEGF. VEGF was lyophilized with or without bovine serum albumin (BSA) and then suspended in solid state in a macromer (acrylated star-poly(epsilon-caprolactone-co-D,L-lactide)) solution containing different concentrations of a free radical initiator, 2,2-dimethoxy-2-phenylacetophenone (DMPA). The protein suspension was then UV-irradiated at different intensities. UV irradiation with the generation of free radicals was detrimental to VEGF stability. BSA preserved the VEGF bioactivity during UV irradiation but provided little protection in the presence of the photo-initiator DMPA. The acrylated macromer acted as a free radical scavenger and effectively preserved VEGF and BSA stability during UV-initiated photo-polymerization. The detrimental effect of UV radiation with free radical generation on VEGF stability during device manufacture can be eliminated by choosing the proper bulking agents coupled with an efficient photo-polymerization reaction.

Low-molecular-weight poly(epsilon-caprolactone-co-1,3-trimethylene carbonate) and poly(1,3-trimethylene carbonate) are potential vehicles for the regio-specific delivery of water-soluble agents. In this paper, the characteristics and the mechanism governing the in vitro release of a model water-soluble drug, vitamin B12, from these polymer vehicles were determined. The loading of vitamin B12 was kept to 1 w/w%. The oligomers examined ranged from amorphous, high viscosity to crystalline but low viscosity. The oligomers did not degrade appreciably in vitro. The total fraction of vitamin B12 released increased as the crystallinity of the oligomers decreased, reaching nearly total release only for the completely amorphous oligomers. The rate of release was fastest for the amorphous oligomers and dependent on their viscosity. Inclusion of a more osmotically active agent, trehalose, into the vitamin B12 particles through co-lyophilization resulted in enhanced total fraction released and a faster release rate. The results are consistent with an osmotically driven release mechanism.