Effect of water activity and gaseous phase relative humidity on microcrystalline cellulose water contact angle measured by the Washburn technique

Impact of immediate release film coating on the disintegration process of tablets

Pharmaceutical tablets are often coated with a layer of polymeric material to protect the drug from environmental degradation, facilitate the packaging process, and enhance patient compliance. However, the detailed effects of such coating layers on drug release are not well understood. To investigate this, flat-faced pure microcrystalline cellulose tablets with a diameter of 13 mm and a thickness between 1.5 mm to 1.6 mm were directly compressed, and a film coating layer with a thickness of 80 μm to 120 μm was applied to one face of these tablets. This tablet geometry and immediate release film coating were chosen as a model system to understand how the film coating interacts with the tablet core. The coating hydration and dissolution process was studied using terahertz pulsed imaging, while optical coherence tomography was used to capture further details on the swelling process of the polymer in the coated tablet. The study investigated the film coating polymer dissolution process and found the gelling of dissolving polymer restricted the capillary liquid transport in the core. These findings can help predict the dissolution of film coating within the typical range of thickness (30 μm to 40 μm) and potentially be extended to understand modified release coating formulations.

Sustained Delivery of Methylsulfonylmethane from Biodegradable Scaffolds Enhances Efficient Bone Regeneration

Introduction

As a popular dietary supplement containing sulfur compound, methylsulfonylmethane (MSM) has been widely used as an alternative oral medicine to relieve joint pain, reduce inflammation and promote collagen protein synthesis. However, it is rarely used in developing bioactive scaffolds in bone tissue engineering.

Methods

Three-dimensional (3D) hydroxyapatite/poly (lactide-co-glycolide) (HA/PLGA) porous scaffolds with different doping levels of MSM were prepared using the phase separation method. MSM loading efficiency, in vitro drug release as well as the biological activity of MSM-loaded scaffolds were investigated by incubating mouse pre-osteoblasts (MC3T3-E1) in the uniform and interconnected porous scaffolds.

Results

Sustained release of MSM from the scaffolds was observed, and the total MSM release from 1% and 10% MSM/HA/PLGA scaffolds within 16 days was up to 64.9% and 68.2%, respectively. Cell viability, proliferation, and alkaline phosphatase (ALP) activity were significantly promoted by incorporating 0.1% of MSM in the scaffolds. In vivo bone formation ability was significantly enhanced for 1% MSM/HA/PLGA scaffolds indicated by the repair of rabbit radius defects which might be affected by a stimulated release of MSM by enzyme systems in vivo.

Discussion

Finding from this study revealed that the incorporation of MSM would be effective in improving the osteogenesis activity of the HA/PLGA porous scaffolds.

Superstrong, Lightweight, and Exceptional Environmentally Stable SiO2@GO/Bamboo Composites

Development of lightweight structural materials from fast-growing bamboos is of great significance to building a sustainable society. However, previously developed structural bamboos by delignification combined with densification would easily fail under large external loading after exposure to water due to structure collapse, severely limiting their practical applications. Here, we demonstrate an ultrastrong and exceptional environmentally stable bamboo composite consisting of a graphene oxide (GO)/bamboo core and hierarchical SiO₂ protection layer. The GO/bamboo composite exhibits ultrahigh tensile strength (641.6 MPa), superb flexural strength (428.4 MPa), and excellent toughness (17.5 MJ/m³), which are increased by about 480, 250, and 360% compared with natural bamboo, respectively. As a result, the specific tensile strength of the GO/bamboo composite is up to 513.3 MPa·cm³/g due to its low density (1.25 g/cm³), outperforming engineering structural materials such as aluminum alloys, steels, and titanium alloys. These large improvements benefit from the well-preserved bamboo scaffold and the strong hydrogen bonds between bamboo fibers and GO nanosheets. On the other hand, the SiO₂@GO/bamboo composite shows superhydrophobicity due to the construction of hierarchical SiO₂ layers, which endows it with outstanding water resistance. Moreover, the bamboo composite shows an ultralow coefficient of thermal expansion (≈2.3 × 10^-6 K^-1), indicating its excellent dimensional stability. Considering the ultrahigh mechanical performance and outstanding environmental stability, the developed lightweight SiO₂@GO/bamboo composite is hopeful to be a green and sustainable structural material for practical engineering applications.

Influence of several biodegradable components added to pure and nanosilver-doped PMMA bone cements on its biological and mechanical properties

Acrylic bone cements (BC) are wildly used in medicine. Despite favorable mechanical properties, processability and inject capability, BC lack bioactivity. To overcome this, we investigated the effects of selected biodegradable additives to create a partially-degradable BC and also we evaluated its combination with nanosilver (AgNp). We hypothesized that using above strategies it would be possible to obtain bioactive BC. The Cemex was used as the base material, modified at 2.5, 5 or 10 wt% with either cellulose, chitosan, magnesium, polydioxanone or tricalcium-phosphate. The resulted modified BC was examined for surface morphology, wettability, porosity, mechanical and nanomechanical properties and cytocompatibility. The composite BC doped with AgNp was also examined for its release and antibacterial properties. The results showed that it is possible to create modified cement and all studied modifiers increased its porosity. Applying the additives slightly decreased BC wettability and mechanical properties, but the positive effect of the additives was observed in nanomechanical research. The relatively poor cytocompatibility of modified BC was attributed to the unreacted monomer release, except for polydioxanone modification which increased cells viability. Furthermore, all additives facilitated AgNp release and increased BC antibacterial effectiveness. Our present studies suggest the optimal content of biodegradable component for BC is 5 wt%. At this content, an improvement in BC porosity is achieved without significant deterioration of BC physical and mechanical properties. Polydioxanone and cellulose seem to be the most promising additives that improve porosity and antibacterial properties of antibiotic or nanosilver-loaded BC. Partially-degradable BC may be a good strategy to improve their antibacterial effectiveness, but some caution is still required regarding their cytocompatibility. STATEMENT OF SIGNIFICANCE: The lack of bone cement bioactivity is the main limitation of its effectiveness in medicine. To overcome this, we have created composite cements with partially-degradable properties. We also modified these cements with nanosilver to provide antibacterial properties. We examined five various additives at three different contents to modify a selected bone cement. Our results broaden the knowledge about potential modifiers and properties of composite cements. We selected the optimal content and the most promising additives, and showed that the combination of these additives with nanosilver would increase cements` antibacterial effectiveness. Such modified cements may be a new solution for medical applications.

Toward Sustainable Multifunctional Coatings Containing Nanocellulose in a Hybrid Glass Matrix

We report on a sustainable route to protective nanocomposite coatings, where one of the components, nanocellulose fibrils, is derived from trees and the glass matrix is an inexpensive sol-gel organic-inorganic hybrid of zirconium alkoxide and an epoxy-functionalized silane. The hydrophilic nature of the colloidal nanocellulose fibrils is exploited to obtain a homogeneous one-pot suspension of the nanocellulose in the aqueous sol-gel matrix precursors solution. The mixture is then sprayed to form nanocomposite coatings of a well-dispersed, random in-plane nanocellulose fibril network in a continuous organic-inorganic glass matrix phase. The nanocellulose incorporation in the sol-gel matrix resulted in nanostructured composites with marked effects on salient coating properties including optical transmittance, hardness, fracture energy, and water contact angle. The particular role of the nanocellulose fibrils on coating fracture properties, important for coating reliability, was analyzed and discussed in terms of fibril morphology, molecular matrix, and nanocellulose/matrix interactions.

Strategies to analyse data obtained from liquid intrusion experiments of loose porous materials

Liquid intrusion remains one of the most common methods to measure the contact angle of liquids to powders. However, as there are two unknown variables in the Washburn equation: the material constant (that is, the pore structure of the powder bed) and the contact angle of the liquid to the powder, this method requires the use of two liquids-a liquid of interest (the probe liquid) and a reference liquid. The reference liquid should, ideally, make a contact angle of 0° to the sample. However, in practice a low surface tension liquid is normally selected. This paper proposes a more standardised approach for the selection of the reference liquid based on experimental data. Additionally, a major assumption of the liquid intrusion method is that the pore structure, as measured by the material constant, C, is identical for all powder beds (provided that the same packing procedure is used for the same samples). In real systems, however, this is an approximation, and not likely to hold strictly true. Therefore, difficulties may arise with data analysis as there is a potential uncertainty in the most appropriate order to divide the gradient of the probe liquid by the gradient of the reference liquid. This paper proposes three specific methods of analysing such data, each with their own advantages and limitations. Hence, the selection of which method should be used is criteria-based, assessed on the basis of the obtained data.