Mini-review antimicrobial smart materials: the future’s defense against wound infections

The overuse of antibiotics to treat bacterial infections along with bacteria’s propensity to form biofilm communities has resulted in an alarming rise in drug-resistant microbes. Current approaches to infection surveillance and biofilm clearance in wounds are severely limited, requiring new biomaterials-based strategies to address this problem. To that end, a range of antimicrobial smart materials have been developed that change their properties in response to bacteria-induced external stimuli, providing tools with an additional level of complexity for defending against microbes. Researchers have tried to tackle this issue using materials that respond to the unique pH, temperature, and enzymatic changes that are induced by bacteria in wounds. These environmental responses are coupled with mechanisms to kill surrounding bacteria and/or to signal infection. For example, bacteria-responsive biomaterial solubilization (transition from non-solubilized solid material to solubilized liquid solution), swelling (volumetric increase due to absorption of surrounding media), de-swelling, degradation, or shape change can be coupled with drug release and/or activation or biofilm disruption, inhibition, or destruction. These materials provide a foundation for future work and improvements related to enhanced infection surveillance, increased specificity of infection response, and effective clearance of biofilms from wound surfaces

Extended controlled-release of drugs and nanoparticles from shape memory polymers

ract The ability to externally control release from implants offers a safer and more efficient way of delivering drugs to the body as compared to traditional drug depots that rely upon diffusion and do not allow for a change in dosage after implantation. Previous studies employed magnetic nanoparticle (NP)-loaded shape memory polymer (SMP) films to determine if magnetic actuation could be used to release a model drug (rhodamine B) from strained and unstrained samples and to establish structure/property relationships regarding drug release from SMPs. This previous study was limited by short release time characterization periods (7 hours) and does not provide long-term release information from these scaffolds. To address this limitation, the current study analyzed how magnetic actuation affects release of rhodamine B from both strained and unstrained SMP films with varied chemistries (crosslinked and uncrosslinked) in accelerated hydrolytic (0.1M NaOH), accelerated oxidative (20% H2O2), and ‘real time’ (PBS) media over 26 days. As a proof-of-concept for further control over release, rhodamine B was first loaded into microparticles (µP), which were subsequently incorporated into SMP scaffolds to evaluate release over time. General trends show that magnetic actuation in samples containing NPs increased release relative to those without. Linear (uncrosslinked) samples release significantly more rhodamine B than crosslinked samples. In these long-term studies, straining samples did not have an effect on release rates compared with non-strained samples. ‘Real time’ media allowed for the highest measured release. Accelerated oxidative media resulted in the lowest measured release, which is attributed to H2O2 oxidation of the rhodamine B. Lastly, incorporation of rhodamine B into microparticles prior to loading into films completely eliminated release of rhodamine B at the given mass used. This work acts as a proof-of-concept for controlling sustained drug delivery by varying SMP chemistry, straining, magnetic NP incorporation, and drug-loaded microparticles

Introduction to Documentary Papyrology

Первая в отечественной литературе работа, всесторонне рассматривающая проблемы документальной папирологии. Большое внимание уделено вопросам общей папирологии (в том числе и литературной): предмету папирологии, истории папирологии, реставрации и консервации папирусов, принципам публикации текстов, составления публикационных серий, библиографий, словарей, руководств, хрестоматий, новым методам обработки текстов и т.д. Рассматриваются новые направления, дискуссионные проблемы с учетом новейшей литературы. Особо освещается вклад советских исследователей в папирологию (с приведением исчерпывающей библиографии) и развитие ее в социалистических странах. К книге приложен полный список переводов греческих папирусов, изданных в СССР

Shape Memory Polymer Foams with Phenolic Acid-Based Antioxidant Properties

Phenolic acids (PAs) are natural antioxidant agents in the plant kingdom that are part of the human diet. The introduction of naturally occurring PAs into the network of synthetic shape memory polymer (SMP) polyurethane (PU) foams during foam fabrication can impart antioxidant properties to the resulting scaffolds. In previous work, PA-containing SMP foams were synthesized to provide materials that retained the desirable shape memory properties of SMP PU foams with additional antimicrobial properties that were derived from PAs. Here, we explore the impact of PA incorporation on SMP foam antioxidant properties. We investigated the antioxidant effects of PA-containing SMP foams in terms of in vitro oxidative degradation resistance and cellular antioxidant activity. The PA foams showed surprising variability; p-coumaric acid (PCA)-based SMP foams exhibited the most potent antioxidant properties in terms of slowing oxidative degradation in H2O2. However, PCA foams did not effectively reduce reactive oxygen species (ROS) in short-term cellular assays. Vanillic acid (VA)- and ferulic acid (FA)-based SMP foams slowed oxidative degradation in H2O2 to lesser extents than the PCA foams, but they demonstrated higher capabilities for scavenging ROS to alter cellular activity. All PA foams exhibited a continuous release of PAs over two weeks. Based on these results, we hypothesize that PAs must be released from SMP foams to provide adequate antioxidant properties; slower release may enable higher resistance to long-term oxidative degradation, and faster release may result in higher cellular antioxidant effects. Overall, PCA, VA, and FA foams provide a new tool for tuning oxidative degradation rates and extending potential foam lifetime in the wound. VA and FA foams induced cellular antioxidant activity that could help promote wound healing by scavenging ROS and protecting cells. This work could contribute a wound dressing material that safely releases antimicrobial and antioxidant PAs into the wound at a continuous rate to ideally improve healing outcomes. Furthermore, this methodology could be applied to other oxidatively degradable biomaterial systems to enhance control over degradation rates and to provide multifunctional scaffolds for healing

Analysis of Schwalbe′s Line (Limbal Smooth Zone) by Scanning Electron Microscopy and Optical Coherence Tomography in Human Eye Bank Eyes

Purpose: Implantation of intraocular devices may become critical as they decrease in size in the future. Therefore, it is desirable to evaluate the relationship between radial location and Schwalbe′s line (smooth zone) by examining its width with scanning electron microscopy (SEM) and to correlate this with observations by optical coherence tomography (OCT). Methods: Full corneoscleral rings were obtained from twenty-six formalin-fixed human phakic donor eyes. SEM of each eye yielded a complete montage of the smooth zone, from which the area was measured, and width was determined in each quadrant. In three different eyes, time domain anterior segment OCT (Visante, Carl Zeiss Meditec Inc., Dublin, CA, USA) and spectral domain OCT (Cirrus 4.0, Carl Zeiss Meditec Inc., Dublin, CA, USA) were used to further characterize Schwalbe′s line. Results: The overall smooth zone width was 79±22 μm, (n=15) ranging from 43 to 115 μm. The superior quadrant (103±8 μm, n=19), demonstrated significantly wider smooth zone than both the nasal (71±5 μm, n=19, P0.05). SEM findings of the smooth zone were correlated with visualization of Schwalbe′s line by Cirrus and Visante OCT imaging. Conclusion: The smooth zone appears widest superiorly and thinnest inferonasally, suggesting that as glaucoma surgical devices become smaller, their placement could be targeted clinically by using OCT with preference to the superior quadrant, to minimize damage to the corneal endothelium