Novel air-liquid interface culture model to investigate stiffness-dependent behaviors of alveolar epithelial cells

Pulmonary alveoli are functional units in gas exchange in the lung, and their dysfunctions in lung diseases such as interstitial pneumonia are accompanied by fibrotic changes in structure, elevating the stiffness of extracellular matrix components. The present study aimed to test the hypothesis that such changes in alveoli stiffness induce functional alteration of epithelial cell functions, exacerbating lung diseases. For this, we have developed a novel method of culturing alveolar epithelial cells on polyacrylamide gel with different elastic modulus at an air-liquid interface. It was demonstrated that A549 cells on soft gels, mimicking the modulus of a healthy lung, upregulated mRNA expression and protein synthesis of surfactant protein C (SFTPC). By contrast, the cells on stiff gels, mimicking the modulus of the fibrotic lung, exhibited upregulation of SFTPC gene expression but not at the protein level. Cell morphology, as well as cell nucleus volume, were also different between the two types of gels.

Labile assembly of a tardigrade protein induces biostasis

Tardigrades are microscopic animals that survive desiccation by inducing biostasis. To survive drying tardigrades rely on intrinsically disordered CAHS proteins, which also function to prevent perturbations induced by drying in vitro and in heterologous systems. CAHS proteins have been shown to form gels both in vitro and in vivo, which has been speculated to be linked to their protective capacity. However, the sequence features and mechanisms underlying gel formation and the necessity of gelation for protection have not been demonstrated. Here we report a mechanism of fibrillization and gelation for CAHS D similar to that of intermediate filament assembly. We show that in vitro, gelation restricts molecular motion, immobilizing and protecting labile material from the harmful effects of drying. In vivo, we observe that CAHS D forms fibrillar networks during osmotic stress. Fibrillar networking of CAHS D improves survival of osmotically shocked cells. We observe two emergent properties associated with fibrillization; (i) prevention of cell volume change and (ii) reduction of metabolic activity during osmotic shock. We find that there is no significant correlation between maintenance of cell volume and survival, while there is a significant correlation between reduced metabolism and survival. Importantly, CAHS D's fibrillar network formation is reversible and metabolic rates return to control levels after CAHS fibers are resolved. This work provides insights into how tardigrades induce reversible biostasis through the self-assembly of labile CAHS gels.

In-situ gel: A smart carrier for drug delivery

In-situ gel technology is a promising drug delivery strategy that undergoes a 'sol to gel' transition upon administration, providing controlled and prolonged drug release. These gels are composed of cross-linked 3D networks of polymers, with hydrogels being a specific type of absorbing water while retaining their shape. Gelation can be triggered by various stimuli, such as temperature, pH, ions, and light. They offer several advantages like improved patient compliance, extended drug residence time, localized drug delivery, etc, but also have some disadvantages like drug degradation and limited mechanical strength. In-situ gel falls into three categories: temperature-sensitive, ion-sensitive, and pH-sensitive, but multi-responsive gels that respond to multiple stimuli have better drug release characteristics. The mechanism of in-situ gel formation involves physical and chemical mechanisms. There are various applications of in-situ gel, like ocular drug delivery, nose-to-brain delivery, etc. In this review, we have discussed the types, and mechanisms of in-situ gel & use of in-situ gel in the treatment of different diseases through various routes like buccal, vaginal, ocular, nasal, etc., along with its use in targeted drug delivery.

Tocopherol succinate-loaded ethosomal gel synthesized by cold method technique: Deeper biophysical characterizations for translational application on human skin

BACKGROUND

Tocopherols are well-known antioxidant and moisturizing agent. Tocopherol succinate (TS) are widely used in many skin products especially used in anti-aging and skin whitening product formulation.

AIM

We previously reported the successful synthesis and preliminary characterizations of stable TS ethosomal gels (TSEG) (DOI: 10.1111/jocd.14907). Herein, we develop and further characterize TSEG to enhance the stability of the developed formulation with increased permeation through skin.

METHODS

Cold method technique was used to prepare TS ethosomes. The developed ethosomal vesicle size was 250 nm, which allowed TS to penetrate through the stratum corneum layer and act on melanocytes. For stability study was assessed by thermogravimetric analysis (TGA) by placing TSEG and unloaded/control ethosomal gel (CEG) at various temperature conditions, that is, 8°C, 25°C, 40°C, and 40°C ± 75% RH for 3 months. Organoleptic evaluation was done in terms of color, odor, and phase separation. Transmission electron microscopy (TEM), Fourier Transform infrared spectroscopy (FTIR), x-ray diffraction spectroscopy (XRD), zeta potential (ZP) and particle size (PS) was used for TSEG physical characterizations. In vitro dissolution and ex-vivo permeation studies (using Franz diffusion cell) were performed for both TSEG and CEG formulations. Human women (N = 34) were used to evaluate in vivo biophysical parameters including erythema, melanin, moisture content, sebum level, and skin elasticity.

RESULTS

Developed formulation was highly thermostable during the 3 months. Erythema, melanin, and sebum level decreased while marked improvement (p < 0.05) in moisture content and elasticity have been observed for the developed TSEG.

CONCLUSION

The developed TSEG formulation was found to be efficient, safe (no adverse effects observed), stable (at least for 3 months), and easy to use for topical application with improved skin complexation and skin integrity.

Investigating the Role of Extracellular Matrix Stiffness in Modulating the Ferroptosis Process in Hepatocellular Carcinoma Cells via Scanning Electrochemical Microscopy

Extracellular matrix (ECM) stiffness modulates a variety of cellular processes, including ferroptosis, a process with significant potential implications for hepatocellular carcinoma (HCC) fibrosis and cirrhosis. However, the exact relationship between ECM stiffness and HCC ferroptosis is yet unclarified, partially due to the lack of in situ information on key parameters of the ferroptosis process of living HCC cells. This study pioneers the use of in vitro mechanical microenvironment models of HCC and the scanning electrochemical microscopy (SECM) technique for understanding this interplay. We first cultured HuH7 cells on 4.0, 18.0, and 44.0 kPa polyacrylamide (PA) gels to simulate early, intermediate, and advanced HCC ECM stiffness, respectively. Then, we used SECM to in situ monitor changes in cell membrane permeability, respiratory activity, and reactive oxygen species (ROS) levels of erastin-induced HuH7 cells on PA gels, finding that increasing ECM stiffness potentiates ferroptosis, including increased membrane permeabilization and H2O2 release as well as reduced respiratory activity. Through further transcriptome sequencing and molecular biology measurements, we identified a critical role for focal adhesion kinase (FAK)-mediated yes-associated protein (YAP) in regulating the ferroptosis process dependent on ECM stiffness, which provides novel insights into the mechanical regulation of ferroptosis in HCC cells and may pave the way for innovative therapeutic strategies.

Ultra-Rapid and Specific Gelation of Collagen Molecules for Transparent and Tough Gels by Transition Metal Complexation

Collagen is the most abundant protein in the human body and one of the main components of stromal tissues in tumors which have a high elastic modulus of over 50 kPa. Although collagen has been widely used as a cell culture scaffold for cancer cells, there have been limitations when attempting to fabricate a tough collagen gel with cells like a cancer stroma. Here, rapid gelation of a collagen solution within a few minutes by transition metal complexation is demonstrated. Type I collagen solution at neutral pH shows rapid gelation with a transparency of 81% and a high modulus of 1,781 kPa by mixing with K2 PtCl4 solution within 3 min. Other transition metal ions also show the same rapid gelation, but not basic metal ions. Interestingly, although type I to IV collagen molecules show rapid gelation, other extracellular matrices  do not exhibit this phenomenon. Live imaging of colon cancer organoids in 3D culture indicates a collective migration property with modulating high elastic modulus, suggesting activation for metastasis progress. This technology will be useful as a new class of 3D culture for cells and organoids due to its facility for deep-live observation and mechanical stiffness adjustment.

Exploring the difference in the mechanics of vascular smooth muscle cells from wild-type and apolipoprotein-E knockout mice

Atherosclerosis-related cardiovascular diseases are a leading cause of mortality worldwide. Vascular smooth muscle cells (VSMCs) comprise the medial layer of the arterial wall and undergo phenotypic switching during atherosclerosis to a synthetic phenotype capable of proliferation and migration. The surrounding environment undergoes alterations in extracellular matrix (ECM) stiffness and composition and an increase in cholesterol content. Using an atherosclerotic murine model, we analyzed how the mechanics of VSMCs isolated from Western diet-fed apolipoprotein-E knockout (ApoE-/-) and wild-type (WT) mice were altered during atherosclerosis. Increased stiffness of ApoE-/- VSMCs correlated with a greater degree of stress fiber alignment, as evidenced by atomic force microscopy (AFM)-generated force maps and stress fiber topography images. On type-1 collagen (COL1)-coated polyacrylamide (PA) gels (referred to as substrate) of varying stiffness, ApoE-/- VSMCs had lower adhesion forces to COL1 and N-cadherin (N-Cad) compared with WT cells. ApoE-/- VSMC stiffness was significantly greater than that of WT cells. Cell stiffness increased with increasing substrate stiffness for both ApoE-/- and WT VSMCs. In addition, ApoE-/- VSMCs showed an enhanced migration capability on COL1-coated substrates and a general decreasing trend in migration capacity with increasing substrate stiffness, correlating with lowered adhesion forces as compared with WT VSMCs. Altogether, these results demonstrate the potential contribution of the alteration in VSMC mechanics in the development of atherosclerosis.

Electromechanical response performance of a reinforced biomass gel artificial muscle based on natural polysaccharide of sodium alginate doped with an ionic liquid for micro-nano regulation

In this paper, a reinforced Biomass Gel Artificial Muscle (BGAM) was fabricated by natural polysaccharide of Sodium Alginate (SA) doped with an Ionic Liquid (IL) of 1-ethyl-3-methylimidazolium tetrafluoroborate ([EMIm][BF₄]). Micro-nano regulation effect and reinforcement mechanism of IL doping content on electromechanical response performance of BGAM were researched during a single cycle and repeated cycles. Then, a green fabrication process and a set of valid test methods for BGAM were proposed in detail. The experimental results showed that when IL doping content was 4 mL, the BGAM achieved optimal modification, with a porosity of 70.47%, where it internally adopted the porous polymer structure of ion channels. Additionally, specific capacitance of BGAM attained a maximum value of 126.98 mF/g, and the inner resistance and elastic modulus reached minimum values of 2.018 Ω and 1.871 MPa, separately. Thus, the optimal working life and output-force density values, namely, 1720 s and 13.072 mN/g, respectively, were also determined for the BGAM.

Effects of salt and heat treatment on the physicochemical properties, microstructure, secondary structure, and simulated in vitro gastrointestinal digestion of duck egg white

BACKGROUND

The texture and structure of the duck egg white (DEW) gel under salt and heat treatment are crucial to its digestibility. Specifically, the structural changes of food protein gels have been recognized for their potential to regulate in vitro digestion. In this study, the effects of gel characteristics and simulated in vitro gastrointestinal digestion of DEW under combined salt and heat treatment were investigated.

RESULTS

With the increase in salting time and temperature, a porous opaque gel with large particles was formed, the moisture content of DEW showed a downward trend, and the same was true for hardness changes. The microstructure suggested that, with the penetration of NaCl, DEW proteins were denatured, and the protein molecules gradually unfolded and then aggregated after 7 days. The secondary structure revealed that, as the salting time and temperature increased, the proportion of intermolecular β-sheets and α-helices decreased. In terms of in vitro digestion, the highest digestibility was obtained at 14 days of salting combined with 100 °C heat treatment, and the digestibility was the lowest when marinated for 7 days at 121 °C. Liquid chromatography and tandem mass spectrometry (LC-MS/MS) indicated that the number of different types of peptides and specific peptides was positively correlated with the salting time and temperature of the DEW at the end of gastric digestion.

CONCLUSIONS

Heat treatment at 100 °C has a higher in vitro digestibility than at 121 °C. Gels with low hardness, large pores, and rough textures are easier to digest by pepsin and release more peptides. © 2021 Society of Chemical Industry.

Effects of mid-stage nitrogen application timing on the morphological structure and physicochemical properties of japonica rice starch

BACKGROUND

Nitrogen management of crops, especially when mid-stage nitrogen is applied, is a key factor affecting the yield and grain quality of rice (Oryza sativa). Here, the timing of mid-stage nitrogen application was evaluated for its effect on rice grain quality by assessing the morphological structure and physicochemical properties of starch from two japonica rice cultivars growing in fields (Nangeng 9108 and Nangeng 5055).

RESULTS

The experiment was arranged in a split-plot design, with the two rice cultivars as the main plot factor and three timings of mid-stage nitrogen application as the within-plot factor. Briefly, three applications were made: at the emergence of the top-sixth-leaf (ahead), the top-fourth-leaf (normal), and the top-second-leaf (delayed) of the main stem. Delaying mid-stage nitrogen application caused the starch granule surface to become uneven and significantly reduced its particle size, whereas it increased the polished rice rate, chalkiness degree, and protein content. Furthermore, the apparent amylose content decreased with a delay in mid-stage nitrogen application, thereby resulting in higher relative crystallinity, swelling power, water solubility, gelatinization enthalpy, and low retrogradation. Finally, we also found that delaying this nitrogen application lowered the characteristic values of rice flour viscosities, leading to cooking quality deterioration.

CONCLUSION

These results therefore suggest that delaying mid-stage nitrogen application enhances the processing and nutritional qualities of japonica rice but evidently has an adverse effect upon its appearance and cooking qualities. © 2020 Society of Chemical Industry.

In Vitro Permeability, Irritability, and Release Evaluation of Commonly Used Topical Diclofenac Gel Preparations (1%, 5%, and 10%)

Recently, there has been an increase in the use of compounded topical pain preparations, raising concerns that clinicians and patients may not be aware of the potential safety risks. Topical diclofenac is one of the most widely used pain medications, often used for joint ailments such as osteoarthritis and other musculoskeletal pain. Systemic exposure to diclofenac has a dose-related risk for gastrointestinal, cardiovascular, and renal adverse events, particularly in elderly patients. Topical diclofenac preparations are frequently compounded in pharmacies at the concentrations of 1% to 10% (or higher) with or without other active ingredients such as camphor. Considering the significantly higher strengths of the compounded preparations as compared to the commercially available products (1% to 3%) and the frequency of application (sometimes up to six times a day), concerns arise as to the levels of absorption with these formulations and their potential toxicity. The objective of this initial study was formulated in an attempt to shed light on safety concerns of topical diclofenac preparations. A study was designed to evaluate the in vitro release, irritability, and permeability of three different concentrations of compounded diclofenac gels (1%, 5%, and 10%) in PLO GEL MEDIFLO and VersaPro Gel bases. Using MatTek's EpiDerm system, skin irritability and the in vitro permeation of compounded diclofenac gels were evaluated. Additionally, the in vitro release profile, drug content, content uniformity, and physical properties of the compounded gels (pH, homogeneity) were assessed. In all cases, the drug content, content uniformity, physical properties, and preparation stability during the recommended beyond-use dating (90 days) were acceptable. The release profiles of all tested preparations followed the Higuchi model. The in vitro skin irritation evaluation of the tested formulations indicated no irritant preparation. The permeability assessment of the formulated gels revealed that there is a correlation between drug release and percutaneous absorption. VersaPro Gelbased preparations, which showed a lower percentage of drug release over the experiment time, showed a significantly lower average flux at steady-state and the average percentage of absorbed dose after 24 hours. The percentage absorption (%abs) from different formulations ranged from 11.18% to 19.6% depending on the gel base. The permeability coefficient, kp, (cm/hr) ranged from 0.019 to 0.037, and the average flux (µg/cm2/hr) ranged from 8.7 to 103 depending on the gel base and the diclofenac concentration. Based on our findings and previously reported data, the possibility exists that higher diclofenac concentrations in compounded topical preparations may lead to significantly higher blood concentrations as compared to commercially available products, which in turn may also lead to serious side effects. Accordingly, there is a need for clinical studies to evaluate the safety of compounded diclofenac preparations with higher diclofenac contents than United States Food and Drug Administrationapproved formulations.

New Insight into Natural Extracellular Matrix: Genipin Cross-Linked Adipose-Derived Stem Cell Extracellular Matrix Gel for Tissue Engineering

The cell-derived extracellular matrix (ECM) is associated with a lower risk of pathogen transfer, and it possesses an ideal niche with growth factors and complex fibrillar proteins for cell attachment and growth. However, the cell-derived ECM is found to have poor biomechanical properties, and processing of cell-derived ECM into gels is scarcely studied. The gel provides platforms for three-dimensional cell culture, as well as injectable biomaterials, which could be delivered via a minimally invasive procedure. Thus, in this study, an adipose-derived stem cell (ADSC)-derived ECM gel was developed and cross-linked by genipin to address the aforementioned issue. The genipin cross-linked ADSC ECM gel was fabricated via several steps, including rabbit ADSC culture, cell sheets, decellularization, freeze-thawing, enzymatic digestion, neutralization of pH, and cross-linking. The physicochemical characteristics and cytocompatibility of the gel were evaluated. The results demonstrated that the genipin cross-linking could significantly enhance the mechanical properties of the ADSC ECM gel. Furthermore, the ADSC ECM was found to contain collagen, fibronectin, biglycan, and transforming growth factor (TGF)-β1, which could substantially maintain ADSC, skin, and ligament fibroblast cell proliferation. This cell-derived natural material could be suitable for future regenerative medicine and tissue engineering application.

Optimizing ophthalmic delivery of a poorly water soluble drug from an aqueous in situ gelling system

Poorly soluble drugs are often unsuitable to incorporate in ocular in situ gelling systems due to the aqueous based gelling formulations and low volumes administered. For such formulations to be successful, the administered drug must have sufficient solubility to diffuse from the formulation to the eye and should not affect the gelation of the in situ gelling material. Drug salt forms can improve the solubility of poorly soluble drugs, however, as in situ gel forming formulations are often designed to be crosslinked by salts (present the lacrimal fluid) it can make salt forms difficult to formulate. The aim of this study was to develop an in situ gel forming ophthalmic formulation of a poorly soluble drug flurbiprofen (FBP) through cyclodextrin complex formation and to analyse the impact on gelation, release and permeation through the cornea. Hydroxypropyl-beta-cyclodextrin (HβCD) was used as a complexing agent and low acyl gellan gum was added to the FBP- HβCD complex as a water soluble in situ gelling polymer. Measurements were performed using rheo-dissolution, which utilises a rheometer with a modified lower plate that has the unique ability to allow rheological measurement and analysis of drug release simultaneously. An ex-vivo permeation study was also performed using porcine cornea. Rheological measurements in terms of elastic (G') and viscous (G″) modulus showed rapid gelation of the formulation upon contact with simulated lacrimal fluid (SLF). Approximately, 97% FBP was released when 10% HβCD was used and release was decreased to 79% when the amount of HβCD was increased to 20%. The percentage of drug permeation through the cornea was 55% in 300 min whereas the marketed non gelling eye drop formulation containing FBP sodium showed only 37% permeation. The data presented here, revealed that not only could a poorly soluble drug be complexed with cyclodextrin and loaded into an in situ gelling system without interfering with the gelation, but also permeability the of the drug improved.

Lornoxicam controlled release transdermal gel patch: Design, characterization and optimization using co-solvents as penetration enhancers

The aim of the current study was to develop membrane-based transdermal patches of lornoxicam gel using oleic acid (OA)and propylene glycol (PG) as penetration enhancers to improve drug delivery across the skin and to evaluate in vivo analgesic and anti-inflammatory activity. For this purpose, nine formulations were developed in accordance with 32 factorial design using Design Expert® 11. The concentration of propylene glycol (X1) and oleic acid (X2) were selected as independent variable whereas Q10 (Y1), flux (Y2) and lag time (Y3) were considered as the response variables. The impact of drug loading, surface area, gel concentration, membrane variation and agitation speed on drug release and permeation was also studied. The skin sensitivity reaction, analgesic activity and anti-inflammatory action of the optimized patch were also determined in Albino Wistar rats. Stability studies were performed for three months at three different temperature conditions. The result suggests that a membrane-based system with controlled zero-order drug release of 95.8 ± 1.121% for 10 h exhibiting flux of 126.51±1.19 μg/cm2/h and lag time of 0.908 ±0.57h was optimized with the desired analgesic and anti-inflammatory effect can be obtained by using propylene glycol and oleic acid co-solvents as a penetration enhancer. The patch was also found stable at 4˚C for a period of 6.44 months. Formulation F9 comprising of 10% PG and 3% OA was selected as an optimized formulation. The study demonstrates that the fabricated transdermal system of lornoxicam can deliver the drug through the skin in a controlled manner with desired analgesic and anti-inflammatory activity and can be considered as a suitable alternative of the oral route.

Chirality Transfer in Coassembled Organogels Enabling Wide-Range Naked-Eye Enantiodifferentiation

Enantiodifferentiation is crucial in organic chemistry, pharmacochemistry, material chemistry, and life science. However, it remains tremendously challenging to achieve a broad enantioselectivity to different types of chiral substrates via a single-material design. Here, we report a coassembled organogel strategy with chirality transfer to make an enantioselective generality possible. This coassembly contains two components: a chiral rigid molecular linker and an achiral block copolymer. Different from routine helically packed chiral self-assemblies, chirality transfer from the linker to the copolymer directed the coassembly to form a phase-segregated twisted nanofiber, in cooperation with H-bonding and microphase segregation. An organogel was accordingly formed by the further cross-linking in ethanol, where the rigid chiral linker served as the scaffold. On this basis, the system becomes highly sensitive, enabling a naked-eye sensing toward the single enantiomer of a diverse series of chiral species (including axial, point, planar, and polymeric chirality) via gel-to-micelle transformation, due to the asymmetric interaction hampering the chirality transfer in the coassembly and destroying the hierarchical structure. Such a strategy, based on a significant amplification of the stereoselective interactions, facilitates a simple and straightforward way to distinguish a broad optical activity independent of devices.

Enhanced Chemical Stability, Intestinal Absorption, and Intracellular Antioxidant Activity of Cyanidin-3-O-glucoside by Composite Nanogel Encapsulation

A composite nanogel was developed for cyanidin-3-O-glucoside (C3G) delivery by combining Maillard reaction and heat gelation. The starting materials utilized were ovalbumin, dextran, and pectin. C3G-loaded nanogel was spherical with a diameter of ∼185 nm, which was maintained over a wide range of pH and NaCl concentrations. The composite nanogel enhanced the chemical stability of C3G under accelerated degradation models and a simulated gastrointestinal tract. Clathrin-mediated, caveolae-mediated, and macropinocytosis-related endocytosis contributed to the higher cellular uptake of nano-C3G than that of free-C3G. The apparent permeability coefficients of C3G increased 2.16 times after nanoencapsulation. The transcytosis of the C3G-bearing nanogel occurred primarily through the clathrin-related pathway and macropinocytosis and followed the "common recycling endosomes-endoplasmic reticulum-Golgi complex-basolateral plasma membrane" route. Moreover, nano-C3G was more efficient in restoring the viability of cells and activities of endogenous antioxidant enzymes than free-C3G in oxidative models, which may be attributed to the former's high cellular absorption.

Plasma-based fast-gelling biohybrid gels for biomedical applications

Blood based biomaterials are widely researched and used in different biomedical applications including cell therapy, drug delivery, sealants etc. due to their biocompatibility and biodegradability. Blood derived gels are successfully used in clinical studies due to the presence of fibrinogen and several platelet growth factors. In spite of their wide applications, it is challenging to use blood-based biomaterials due to their low mechanical stability, poor adhesive property and contamination risk. In this study, we used porcine plasma to form gel in presence of biodegradable synthetic crosslinkers. Mechanical strength of this plasma gel could be tailored by altering the amount of crosslinkers for any desired biomedical applications. These plasma gels, formed by the synthetic crosslinkers, were utilized as a drug delivery platform for wound healing due to their low cytotoxicity. A model drug release study with these plasma gels indicated slow and sustained release of the drugs.

Arabinoxylan-Based Particles: In Vitro Antioxidant Capacity and Cytotoxicity on a Human Colon Cell Line

Background and objectives: Arabinoxylans (AX) can gel and exhibit antioxidant capacity. Previous studies have demonstrated the potential application of AX microspheres as colon-targeted drug carriers. However, the cytotoxicity of AX gels has not been investigated so far. Therefore, the aim of the present study was to prepare AX-based particles (AXM) by coaxial electrospraying method and to investigate their antioxidant potential and cytotoxicity on human colon cells. Materials and Methods: The gelation of AX was studied by monitoring the storage (G') and loss (G'') moduli. The morphology of AXM was evaluated using optical and scanning electron microscopy (SEM). The in vitro antioxidant activity of AX before and after gelation was measured using the 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS+), 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP) methods. In addition, the effect of AX and AXM on the proliferation of human colon cells (CCD 841 CoN) was evaluated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Results: The final G' and G'' values for AX gels were 293 and 0.31 Pa, respectively. AXM presented spherical shape and rough surface with a three-dimensional and porous network. The swelling ratio and mesh size of AXM were 35 g water/g AX and 27 nm, respectively. Gelation decreased the antioxidant activity of AX by 61-64 %. AX and AXM did not affect proliferation or show any toxic effect on the normal human colon cell line CCD 841 CoN. Conclusion: The results indicate that AXM could be promising biocompatible materials with antioxidant activity.

Thermoresponsive Gel Embedded with Adipose Stem-Cell-Derived Extracellular Vesicles Promotes Esophageal Fistula Healing in a Thermo-Actuated Delivery Strategy

Extracellular vesicles (EVs) are increasingly envisioned as the next generation of biological pro-regenerative nanotherapeutic agents, as has already been demonstrated for heart, kidney, liver, and brain tissues; lung injury repair; and skin regeneration. Herein, we explore another potential EV therapeutic application, fistula healing, together with a local minimally invasive delivery strategy. Allogenic extracellular vesicles (EVs) from adipose tissue-derived stromal cells (ASCs) are administered in a porcine fistula model through a thermoresponsive Pluronic F-127 (PF-127) gel, injected locally at 4 °C and gelling at body temperature to retain EVs in the entire fistula tract. Complete fistula healing is reported to be 100% for the gel plus EVs group, 67% for the gel group, and 0% for the control, supporting the therapeutic use of Pluronic F-127 gel alone or combined with EVs. However, only the combination of gel and EVs results in a statistically significant (i) reduction of fibrosis, (ii) decline of inflammatory response, (iii) decrease in the density of myofibroblasts, and (iv) increase of angiogenesis. Overall, we demonstrate that ASC-EV delivery into a PF-127 gel represents a successful local minimally invasive strategy to induce a therapeutic effect in a swine fistula model. Our study presents prospects for EV administration strategies and for the management of post-operative fistulas.

In vitro evaluation of chitosan copper chelate gels as a multimicronutrient feed additive for cattle

BACKGROUND

Effective micronutrient supplementation strategies are critical to ensure optimal health and productivity in livestock. The objective of this study was to develop a copper and vitamin (multimicronutrient) delivery system based on chitosan gel beads, and test its suitability, in vitro, for use as a cattle feed additive.

RESULTS

Chitosan was chelated with copper sulfate to produce millimetre-scale gel matrices (∼2 mm). The copper content was significantly increased (from 61 to 95 mg g by adjusting pH to alkaline conditions post bead formation. The beads could subsequently be loaded with the model vitamin riboflavin to levels as high as 324 µg g^-1 beads. Restricted rehydration of the dried gel matrices in simulated rumen fluid led to a sustained release of riboflavin with no copper released in these neutral conditions for up to 24 h, demonstrating copper rumen bypass. Moreover, sustained release of the mineral was observed in abomasal conditions of pH 2 over a 3 h period.

CONCLUSIONS

The matrices showed rumen bypass for copper yet supplied nutritionally relevant levels of the free mineral in abomasal conditions, as required for effective supplementation in cattle. The controlled-release properties demonstrated by the matrices indicate their potential as a multimicronutrient functional feed additive to enhance cattle nutrition and productivity. © 2018 Society of Chemical Industry.

A Prospective Clinical and Instrumental Study on the Effects of a Transcutaneous Cosmeceutical Gel that is Claimed to Produce CO₂

Carboxytherapy is the therapeutic use of carbon dioxide (CO2) in its gaseous state. Since 1933, carboxytherapy has referred to either the subcutaneous injection of CO2 or percutaneous application in a warm bath. The present clinical study was performed to determine if there were any changes in the dermis after the application of a transcutaneous gel, which is claimed to produce CO2, and, if so, how these changes compared to those with CO2 injection. Ten patients received transcutaneous treatment with the gel on one side of the face and the other side without any product was used as a control. We used videocapillaroscopy with an optic probe (VCSO) to evaluate the changes in the microcirculation of the skin. VCSO was performed for the treated right and untreated left ear lobes in each patient. VCSO was performed before treatment was started (VCSO1) and after 7 days of treatment (VCSO2). A comparison of VCSO1 to VCSO2 showed an increase in the microcirculation, an increase in vertical and horizontal capillaries, and a reduction in the area of ischemia. These results are similar to those observed in other studies with CO2 injection. In conclusion, use of this transcutaneous CO2 gel produced changes in the dermis similar to those observed with subcutaneous injection of CO2.

Identification of candidate genes for gelatinization temperature, gel consistency and pericarp color by GWAS in rice based on SLAF-sequencing

Rice is an important cereal in the world. The study of the genetic basis of important agronomic traits in rice landraces and identification of genes will facilitate the breed improvement. Gelatinization temperature (GT), gel consistency (GC) and pericarp color (PC) are important indices of rice cooking and eating quality evaluation and potential nutritional importance, which attract wide attentions in the application of genetic and breeding. To dissect the genetic basis of GT, GC and PC, a total of 419 rice landraces core germplasm collections consisting of 330 indica lines, 78 japonica lines and 11 uncertain varieties were planted, collected, then GT, GC, PC were measured for two years, and sequenced using specific-locus amplified fragment sequencing (SLAF-seq) technology. In this study, 261,385,070 clean reads and 56,768 polymorphic SLAF tags were obtained, which a total of 211,818 single nucleotide polymorphisms (SNPs) were discovered. With 208,993 SNPs meeting the criterion of minor allele frequency (MAF) > 0.05 and integrity> 0.5, the phylogenetic tree and population structure analysis were performed for all 419 rice landraces, and the whole panel mainly separated into six subpopulations based on population structure analysis. Genome-wide association study (GWAS) was carried out for the whole panel, indica subpanel and japonica subpanel with subset SNPs respectively. One quantitative trait locus (QTL) on chromosome 6 for GT was detected in the whole panel and indica subpanel, and one QTL associated with GC was located on chromosome 6 in the whole panel and indica subpanel. For the PC trait, 8 QTLs were detected in the whole panel on chromosome 1, 3, 4, 7, 8, 10 and 11, and 7 QTLs in the indica subpanel on chromosome 3, 4, 7, 8, 10 and 11. For the three traits, no QTL was detected in japonica subpanel, probably because of the polymorphism repartition between the subpanel, or small population size of japonica subpanel. This paper provides new gene resources and insights into the molecular mechanisms of important agricultural trait of rice phenotypic variation and genetic improvement of rice quality variety breeding.

Dose-dependent effects of rosmarinic acid on formation of oxidatively stressed myofibrillar protein emulsion gel at different NaCl concentrations

The effects of rosmarinic acid (RA) (12, 60 and 300μM/g protein) on the textural properties and stability of oxidized myofibrillar protein (MP) emulsion gels were investigated. A low dose (12µM/g) of RA significantly prevented the loss of thiol and ε-NH2 groups and the unfolding of the oxidized MP. However, a high dose of RA (300µM/g) covalently and non-covalently interacted with the MPs, which induced a significant loss of thiol and ε-NH2 groups and aggregation of the MPs, causing decreased solubility, resulting in a poor three-dimensional emulsion gel network, and hence, higher cooking loss and lower gel strength. Moreover, the emulsifying properties of the MP emulsion gel were jeopardized by 300µM/g RA. A high concentration of NaCl (0.6M) enhanced the interaction between RA and MPs, increasing deterioration of the internal structure and leading to extremely unstable emulsifying properties of the MP emulsion gel.

Modulation of Lipid Digestion Profiles Using Filled Egg White Protein Microgels

Colloidal delivery systems are required to encapsulate, protect, and release active food ingredients, such as vitamins, nutraceuticals, and minerals. In this study, lipid droplets were encapsulated within biopolymer microgels fabricated from egg white proteins using an injection-gelation process. Confocal fluorescence microscopy indicated that lipid droplets were dispersed within a network of cross-linked proteins within the microgels. The properties of the lipid-loaded microgels were compared to those of simple oil-in-water emulsions stabilized by egg white proteins. Light scattering and microscopy measurements indicated that both delivery systems exhibited good stability under acid conditions (pH 3-5) but aggregated at higher pH values as a result of a reduction in electrostatic repulsion. Simulated gastrointestinal tract studies indicated that lipid droplets encapsulated within protein microgels were digested more slowly than free lipid droplets. Our results therefore suggest that egg white protein microgels may be useful for encapsulation and controlled release of hydrophobic bioactive agents.

Diffusion through Pig Gastric Mucin: Effect of Relative Humidity

Mucus covers the epithelium found in all intestinal tracts, where it serves as an important protecting barrier, and pharmaceutical drugs administrated by the oral, rectal, vaginal, ocular, or nasal route need to penetrate the mucus in order to reach their targets. Furthermore, the diffusion in mucus as well as the viscosity of mucus in the eyes, nose and throat can change depending on the relative humidity of the surrounding air. In this study we have investigated how diffusion through gels of mucin, the main protein in mucus, is affected by changes in ambient relative humidity (i.e. water activity). Already a small decrease in water activity was found to give rise to a significant decrease in penetration rate through the mucin gel of the antibacterial drug metronidazole. We also show that a decrease in water activity leads to decreased diffusion rate in the mucin gel for the fluorophore fluorescein. This study shows that it is possible to alter transport rates of molecules through mucus by changing the water activity in the gel. It furthermore illustrates the importance of considering effects of the water activity in the mucosa during development of potential pharmaceuticals.

Electromyography analysis of natural mastication behavior using varying mouthful quantities of two types of gels

The objectives of this study were to examine the effects of mouthful quantities and mechanical properties of gels on natural mastication behaviors using electromyography (EMG). Two types of hydrocolloid gels (A and K) with similar fracture loads but different moduli and fracture strains were served to eleven normal women in 3-, 6-, 12-, and 24-g masses in a randomized order. EMG activities from both masseter muscles were recorded during natural mastication. Because of the similar fracture loads, the numbers of chews, total muscle activities, and entire oral processing times were similar for similar masses of both gel types. Prior to the first swallow, the more elastic K gel with a higher fracture strain required higher muscle activities than the brittle A gel, which had higher modulus. Majority of subjects had preferred sides of chewing, but all subjects with or without preferred sides used both masseters during the consumption of gels. Similar effects of masses and types of gels were observed in EMG activities of both sides of masseters. Contributions of the dominant side of chewing were diminished with increasing masses of gels, and the mass dependency on ratio of the dominant side was more pronounced with K gel. More repetitions of smaller masses required greater muscle activities and longer periods for the consumption of 24-g gel portions. Reduction in the masses with an increased number of repetitions necessitated slower eating and more mastication to consume the gel portions. These observations suggest that chewing using both sides is more effective and unconsciously reduces mastication times during the consumption of gels.

A Combined In Vitro Imaging and Multi-Scale Modeling System for Studying the Role of Cell Matrix Interactions in Cutaneous Wound Healing

Many cell types remodel the extracellular matrix of the tissues they inhabit in response to a wide range of environmental stimuli, including mechanical cues. Such is the case in dermal wound healing, where fibroblast migrate into and remodel the provisional fibrin matrix in a complex manner that depends in part on the local mechanical environment and the evolving multi-scale mechanical interactions of the system. In this study, we report on the development of an image-based multi-scale mechanical model that predicts the short-term (24 hours), structural reorganization of a fibrin gel by fibroblasts. These predictive models are based on an in vitro experimental system where clusters of fibroblasts (i.e., explants) were spatially arranged into a triangular geometry onto the surface of fibrin gels that were subjected to either Fixed or Free in-plane mechanical constraints. Experimentally, regional differences in short-term structural remodeling and cell migration were observed for the two gel boundary conditions. A pilot experiment indicated that these small differences in the short-term remodeling of the fibrin gel translate into substantial differences in long-term (4 weeks) remodeling, particularly in terms of collagen production. The multi-scale models were able to predict some regional differences in remodeling and qualitatively similar reorganization patterns for the two boundary conditions. However, other aspects of the model, such as the magnitudes and rates of deformation of gel, did not match the experiments. These discrepancies between model and experiment provide fertile ground for challenging model assumptions and devising new experiments to enhance our understanding of how this multi-scale system functions. These efforts will ultimately improve the predictions of the remodeling process, particularly as it relates to dermal wound healing and the reduction of patient scarring. Such models could be used to recommend patient-specific mechanical-based treatment dependent on parameters such as wound geometry, location, age, and health.

Impact of Protein Gel Porosity on the Digestion of Lipid Emulsions

The present study sought to understand how the microstructure of protein gels impacts lipolysis of gelled emulsions. The selected system consisted of an oil-in-water (o/w) emulsion embedded within gelatin gels. The gelatin-gelled emulsions consisted of a discontinuous network of aggregated emulsion droplets (mesoscale), dispersed within a continuous network of gelatin (microscale). The viscoelastic properties of the gelled emulsions were dominated by the rheological behavior of the gelatin, suggesting a gelatin continuous microstructure rather than a bicontinuous gel. A direct relationship between the speed of fat digestion and gel average mesh size was found, indicating that the digestion of fat within gelatin-gelled emulsions is controlled by the ability of the gel's microstructure to slow lipase diffusion to the interface of fat droplets. Digestion of fat was facilitated by gradual breakdown of the gelatin network, which mainly occurred via surface erosion catalyzed by proteases. Overall, this work has demonstrated that the lipolysis kinetics of gelled emulsions is driven by the microstructure of protein gels; this knowledge is key for the future development of microstructures to control fat digestion and/or the delivery of nutrients to different parts of the gastrointestinal tract.

Excess Secretion of Gel-Forming Mucins and Associated Innate Defense Proteins with Defective Mucin Un-Packaging Underpin Gallbladder Mucocele Formation in Dogs

Mucosal protection of the gallbladder is vital yet we know very little about the mechanisms involved. In domestic dogs, an emergent syndrome referred to as gallbladder mucocele formation is characterized by excessive secretion of abnormal mucus that results in obstruction and rupture of the gallbladder. The cause of gallbladder mucocele formation is unknown. In these first mechanistic studies of this disease, we investigated normal and mucocele-forming dog gallbladders to determine the source, identity, biophysical properties, and protein associates of the culprit mucins with aim to identify causes for abnormal mucus behavior. We established that mucocele formation involves an adoptive excess secretion of gel forming mucins with abnormal properties by the gallbladder epithelium. The mucus is characterized by a disproportionally significant increase in Muc5ac relative to Muc5b, defective mucin un-packaging, and mucin-interacting innate defense proteins that are capable of dramatically altering the physical and functional properties of mucus. These findings provide an explanation for abnormal mucus behavior and based on similarity to mucus observed in the airways of people with cystic fibrosis, suggest that abnormal mechanisms for maintenance of gallbladder epithelial hydration may be an instigating factor for mucocele formation in dogs.

Reversibility and Viscoelastic Properties of Micropillar Supported and Oriented Magnesium Bundled F-Actin

Filamentous actin is one of the most important cytoskeletal elements. Not only is it responsible for the elastic properties of many cell types, but it also plays a vital role in cellular adhesion and motility. Understanding the bundling kinetics of actin filaments is important in the formation of various cytoskeletal structures, such as filopodia and stress fibers. Utilizing a unique pillar-structured microfluidic device, we investigated the time dependence of bundling kinetics of pillar supported free-standing actin filaments. Microparticles attached to the filaments allowed the measurement of thermal motion, and we found that bundling takes place at lower concentrations than previously found in 3-dimensional actin gels, i.e. actin filaments formed bundles in the presence of 5-12 mM of magnesium chloride in a time-dependent manner. The filaments also displayed long term stability for up to hours after removing the magnesium ions from the buffer, which suggests that there is an extensive hysteresis between cation induced crosslinking and decrosslinking.

Enzymatically Active Microgels from Self-Assembling Protein Nanofibrils for Microflow Chemistry

Amyloid fibrils represent a generic class of protein structure associated with both pathological states and with naturally occurring functional materials. This class of protein nanostructure has recently also emerged as an excellent foundation for sophisticated functional biocompatible materials including scaffolds and carriers for biologically active molecules. Protein-based materials offer the potential advantage that additional functions can be directly incorporated via gene fusion producing a single chimeric polypeptide that will both self-assemble and display the desired activity. To succeed, a chimeric protein system must self-assemble without the need for harsh triggering conditions which would damage the appended functional protein molecule. However, the micrometer to nanoscale patterning and morphological control of protein-based nanomaterials has remained challenging. This study demonstrates a general approach for overcoming these limitations through the microfluidic generation of enzymatically active microgels that are stabilized by amyloid nanofibrils. The use of scaffolds formed from biomaterials that self-assemble under mild conditions enables the formation of catalytic microgels while maintaining the integrity of the encapsulated enzyme. The enzymatically active microgel particles show robust material properties and their porous architecture allows diffusion in and out of reactants and products. In combination with microfluidic droplet trapping approaches, enzymatically active microgels illustrate the potential of self-assembling materials for enzyme immobilization and recycling, and for biological flow-chemistry. These design principles can be adopted to create countless other bioactive amyloid-based materials with diverse functions.

Protein/arabinoxylans gels: effect of mass ratio on the rheological, microstructural and diffusional characteristics

Wheat bran arabinoxylan (WBAX) gels entrapping standard model proteins at different mass ratios were formed. The entrapment of protein affected the gel elasticity and viscosity values, which decreased from 177 to 138 Pa. The presence of protein did not modify the covalent cross-links content of the gel. The distribution of protein through the network was investigated by confocal laser scanning microscopy. In mixed gels, protein aggregates forming clusters were detected at protein/polysaccharide ratios higher than 0.25. These clusters were not homogeneously distributed, suggesting that WBAX and protein are located in two different phases. The apparent diffusion coefficient (Dm) of proteins during release from mixed gels was investigated for mass ratios of 0.06 and 0.12. For insulin, Dm increased significantly from 2.64 × 10⁻⁷ to 3.20 × 10⁻⁷ cm²/s as the mass ratio augmented from 0.06 to 0.12. No significant difference was found for Dm values of ovalbumin and bovine serum albumin released from the mixed gels. The results indicate that homogeneous protein/WBAX gels can be formed at low mass ratios, allowing the estimation of Dm by using an analytical solution of the second Fick’s law.

Preparation of TAT peptide-modified poly(N-isopropylacrylamide) microgel particles and their cellular uptake, intracellular distribution, and influence on cytoviability in response to temperature change

Thermo-sensitive microgel particles may exert a swelling force inside cells and influence on cell viability due to their volume transition in response to external temperature change. In this study, cross-linked poly(N-isopropylacrylamide) (PNIPAM) microgel particles with a thermo-responsive volume expansion ability were prepared by precipitation polymerization of NIPAM, poly(ethylene glycol) diacrylate and acrylic acid. To endow the microgel particles with enhanced cellular uptake and visualization, cell penetrating peptide TAT and fluorescent probe were further covalently immobilized. The cellular uptake, intracellular distribution and thermo-responsive cytotoxicity of the microgel particles were studied by co-culture with lung adenocarcinoma (A549) cells. The PNIAPM microgel particles were largely ingested by A549 cells and mainly located in lysosomes. TAT modification enhanced the cellular internalization of particles but did not alter their intracellular distribution. While the PNIPAM microgel particles did not show significant impact on cell viability at 37°C, they caused cytotoxicity to some extent when being cultured at 25°C for 4 h. Doxorubicin loaded PNIPAM microgel particles showed the strongest cytotoxicity when being cultured at 25°C for 4 h, suggesting the combinational effect of intracellular volume expansion and drug release on cells.

Plasmin activity in UHT milk: relationship between proteolysis, age gelation, and bitterness

Plasmin, the major indigenous protease in milk, is linked to quality defects in dairy products. The specificity of plasmin on caseins has previously been studied using purified caseins and in the indigenous peptide profile of milk. We investigated the specificity and proteolytic pathway of plasmin in directly heated UHT milk (>150 °C for <0.2 s) during 14 weeks of storage at 20 °C in relation to age gelation and bitter peptides. Sixty-six peptides from αS- and β-caseins could be attributed to plasmin activity during the storage period, of which 23 were potentially bitter. Plasmin exhibited the highest affinity for the hydrophilic regions in the caseins that most probably were exposed to the serum phase and the least affinity for hydrophobic or phosphorylated regions. The proteolytic pattern observed suggests that plasmin destabilizes the casein micelle by hydrolyzing casein-casein and casein-calcium phosphate interaction sites, which may subsequently cause age gelation in UHT milk.

Dually fluorescent core-shell microgels for ratiometric imaging in live antigen-presenting cells

Core-shell microgels containing sensors/dyes in a matrix were fabricated by two-stage free radical precipitation polymerization method for ratiometric sensing/imaging. The microgels composing of poly(N-isopropylacrylamide) (PNIPAm) shell exhibits a low critical solution temperature (LCST), underwent an entropically driven transition from a swollen state to a deswollen state, which exhibit a hydrodynamic radius of ∼450 nm at 25°C (in vitro) and ∼190 nm at 37°C (in vivo). The microgel’s ability of escaping from lysosome into cytosol makes the microgel be a potential candidate for cytosolic delivery of sensors/probes. Non-invasive imaging/sensing in Antigen-presenting cells (APCs) was feasible by monitoring the changes of fluorescence intensity ratios. Thus, these biocompatible microgels-based imaging/sensing agents may be expected to expand current molecular imaging/sensing techniques into methods applicable to studies in vivo, which could further drive APC-based treatments.

Gelation chemistries for the encapsulation of nanoparticles in composite gel microparticles for lung imaging and drug delivery

The formation of 10-40 μm composite gel microparticles (CGMPs) comprised of ∼100 nm drug containing nanoparticles (NPs) in a poly(ethylene glycol) (PEG) gel matrix is described. The CGMP particles enable targeting to the lung by filtration from the venous circulation. UV radical polymerization and Michael addition polymerization reactions are compared as approaches to form the PEG matrix. A fluorescent dye in the solid core of the NP was used to investigate the effect of reaction chemistry on the integrity of encapsulated species. When formed via UV radical polymerization, the fluorescence signal from the NPs indicated degradation of the encapsulated species by radical attack. The degradation decreased fluorescence by 90% over 15 min of UV exposure. When formed via Michael addition polymerization, the fluorescence was maintained. Emulsion processing using controlled shear stress enabled control of droplet size with narrow polydispersity. To allow for emulsion processing, the gelation rate was delayed by adjusting the solution pH. At a pH = 5.4, the gelation occurred at 3.5 h. The modulus of the gels was tuned over the range of 5 to 50 kPa by changing the polymer concentration between 20 and 70 vol %. NP aggregation during polymerization, driven by depletion forces, was controlled by the reaction kinetics. The ester bonds in the gel network enabled CGMP degradation. The gel modulus decreased by 50% over 27 days, followed by complete gel degradation after 55 days. This permits ultimate clearance of the CGMPs from the lungs. The demonstration of uniform delivery of 15.8 ± 2.6 μm CGMPs to the lungs of mice, with no deposition in other organs, is shown, and indicates the ability to concentrate therapeutics in the lung while avoiding off-target toxic exposure.

Acid induced gelation of soymilk, comparison between gels prepared with lactic acid bacteria and glucono-δ-lactone

The objective of this work was to compare the gelation of soymilk particles induced by the acidification of a commercial starter culture with that resulting by addition of glucono-δ-lactone (GDL). Structure formation was followed using rheology, and the microstructure was observed by confocal microscopy. Acidification of lactic acid bacteria resulted in a higher gelation pH (pH 6.29±0.05) compared to that of a gel induced by GDL (pH 5.9±0.04). This difference was attributed to the longer time available for rearrangements of the soymilk particles in soymilk with starter cultures compared to the fast acidification by GDL. In spite of the earlier gelation pH, there were no observed differences in the final gel stiffness measured at pH 5.1, the value of tan δ, the frequency dependence and the linear viscoelastic range of the gels measured at the final pH. Microstructural observations also showed a similar protein network structure.

Microrheological characterization of collagen systems: from molecular solutions to fibrillar gels

Collagen is the most abundant protein in the extracellular matrix (ECM), where its structural organization conveys mechanical information to cells. Using optical-tweezers-based microrheology, we investigated mechanical properties both of collagen molecules at a range of concentrations in acidic solution where fibrils cannot form and of gels of collagen fibrils formed at neutral pH, as well as the development of microscale mechanical heterogeneity during the self-assembly process. The frequency scaling of the complex shear modulus even at frequencies of ∼10 kHz was not able to resolve the flexibility of collagen molecules in acidic solution. In these solutions, molecular interactions cause significant transient elasticity, as we observed for 5 mg/ml solutions at frequencies above ∼200 Hz. We found the viscoelasticity of solutions of collagen molecules to be spatially homogeneous, in sharp contrast to the heterogeneity of self-assembled fibrillar collagen systems, whose elasticity varied by more than an order of magnitude and in power-law behavior at different locations within the sample. By probing changes in the complex shear modulus over 100-minute timescales as collagen self-assembled into fibrils, we conclude that microscale heterogeneity appears during early phases of fibrillar growth and continues to develop further during this growth phase. Experiments in which growing fibrils dislodge microspheres from an optical trap suggest that fibril growth is a force-generating process. These data contribute to understanding how heterogeneities develop during self-assembly, which in turn can help synthesis of new materials for cellular engineering.

Cu2+ inhibition of gel secretion in the xylem and its potential implications for water uptake of cut Acacia holosericea stems

Maintaining a high rate of water uptake is crucial for maximum longevity of cut stems. Physiological gel/tylosis formation decreases water transport efficiency in the xylem. The primary mechanism of action for post-harvest Cu(2+) treatments in improving cut flower and foliage longevity has been elusive. The effect of Cu(2+) on wound-induced xylem vessel occlusion was investigated for Acacia holosericea A. Cunn. ex G. Don. Experiments were conducted using a Cu(2+) pulse (5 h, 2.2 mM) and a Cu(2+) vase solution (0.5 mM) vs a deionized water (DIW) control. Development of xylem blockage in the stem-end region 10 mm proximal to the wounded stem surface was examined over 21 days by light and transmission electron microscopy. Xylem vessels of stems stood into DIW were occluded with gels secreted into vessel lumens via pits from surrounding axial parenchyma cells. Gel secretion was initiated within 1-2 days post-wounding and gels were detected in the xylem from day 3. In contrast, Cu(2+) treatments disrupted the surrounding parenchyma cells, thereby inhibiting gel secretion and maintaining the vessel lumens devoid of occlusions. The Cu(2+) treatments significantly improved water uptake by the cut stems as compared to the control.

Ultrasound-assisted dextranase entrapment onto Ca-alginate gel beads

In this research work, dextranase has immobilized onto calcium alginate beads using a novel ultrasound method. The process of immobilization of the enzyme was carried out in a one-step ultrasound process. Effects of ultrasound conditions on loading efficiency and immobilization yield of the enzyme onto calcium alginate beads were investigated. Furthermore, the activity of the free and immobilized enzymes prepared with and without ultrasound treatment, as a function of pH, temperature, recyclability and enzyme kinetic parameters, was compared. The maximum loading efficiency and the immobilization yield were observed when the immobilized dextranase was prepared with an ultrasonic irradiation at 25 kHz, 40 W for 15 min, under which the loading efficiency and the immobilization yield increased by 27.21% and 18.77%, respectively, compared with the immobilized enzymes prepared without ultrasonic irradiation. On the other hand, immobilized enzyme prepared with ultrasonic irradiation showed Vmax and KM value higher than that for the immobilized enzyme prepared without ultrasonic irradiation, likewise, both the catalytic and specificity constants of immobilized enzyme prepared with ultrasonic irradiation were higher than that for immobilized enzyme prepared without ultrasound, indicating that, this new ultrasonic method improved the catalytic kinetics activity of immobilized dextranase at all the reaction conditions studied. Compared with immobilized enzyme prepared without ultrasound treatment, the immobilized enzymes prepared with ultrasound irradiation exhibited: a higher pH optimum, optimal reaction temperature, activation energy, and thermal stability, as well as, a higher recyclability, which, illustrating the effectiveness of the sonochemical method. To the best of our knowledge, this is the first report on the effect of ultrasound treatments on the immobilization of dextranase.

Hsp70 chaperone-based gel composition as a novel immunotherapeutic anti-tumor tool

The recent advances in designing Hsp70-based anti-cancer vaccines and the ability of the chaperone to penetrate inside a living cell prompted us to develop a non-invasive method for the treatment of surface tumors. We designed hydrogel-containing gel-forming substances and human recombinant Hsp70 and applied them on the surface of a 7-day-old B16F10 melanoma tumor. According to the results of histochemistry, Hsp70 diffused through skin layer inside the B16 tumor, and this transport was proved by biochemical data. The application of Hsp70 gel reduced the rate of tumor growth by 64% and prolonged the life of animals by 46%. Increased survival was correlated with the enhancement of B16-specific cytotoxicity and up-regulation of gamma-interferon production. Taken together, the data confirm the anti-tumor effect of pure recombinant Hsp70 delivered intratumorally and demonstrate the relevance of a novel non-invasive technology of Hsp70-based therapy.

[The effect of OPTC-shRNA on the bovine retinal pigment epithelial cells and hyalocytes co-culture collagen gel contraction system]

OBJECTIVE

To investigate the OPTC-shRNA inhibiting effect on the opticin expression by the bovine hyalocytes and retina pigment epithelial (RPE) cells co-culture collagen gel contraction system.

METHODS

Experimental study. The OPTC-shRNA expression vector was designed and transfected into bovine RPE cells cultured in vitro. The relative expression and the inhibition rate of the opticin protein were measured by Western blot on days 3, 5 and 7. An in vitro cells co-culture bovine type I collagen gel contraction assay was constructed consisting of the hyalocytes and RPE cells. Six groups were established in this experiments:OPTC-shRNA plasmid transfected RPE cells and hyalocytes (group A), empty plasmid transfected RPE cells and hyalocytes (group B), non-transfected RPE cells and hyalocytes (group C), non-transfected RPE cells (group D), only hyalocytes (group E), and no cells (group F). The collagen gel contractile activities of these groups were compared by One-way ANOVA, SNK-q tests and regression analysis;and the influence of the hyalocytes density variance on the collagen gel contraction in groups A, B and C were also analyzed.

RESULTS

The OPTC-shRNA expression vector with significant inhibition effect was constructed and transfected into bovine RPE cells successfully. The results of Western blot analysis showed that the inhibitory rates on the opticin expression on days 3, 5 and 7 were (83.91 ± 2.88), (84.71 ± 4.27) and (82.85 ± 2.72)%, respectively. Furthermore, the differences among days 3, 5 and 7 were insignificant (F = 1.15, P > 0.05). On day 3, the gel contraction rates for the sub-groups with various hyalocytes densities (2×10(7), 1×10(8) and 5×10(8)/L) in groups A, B and C were: group A: (23.52 ± 2.08), (56.00 ± 1.02), (61.62 ± 1.73)%; group B: (16.56 ± 2.01), (36.41 ± 1.33), (49.56 ± 1.75)%; group C: (15.75 ± 1.37), (37.45 ± 1.14), (48.45 ± 1.97)%. The gel contraction rates for groups D and E were (12.18 ± 0.95)% and (10.95 ± 0.93)%, respectively; no gel contraction was observed in group F. Pairwise comparisons of the gel contraction rates were performed by SNK-q test among groups A, B and C for various hyalocyte densities. In the 2×10(7)/L cell density group, the differences between groups A and B or C were significant (q = 11.38, 2.72, respectively, P both < 0.05), the differences between B and C were insignificant (q = 1.34, P > 0.05). In the 1×10(8)/L cell density group, the differences between groups A and B or C were significant (q = 8.83, 46.22, respectively, P both < 0.05), the differences between B and C were insignificant (q = 1.34, P > 0.05). In the 5×10(8)/L cell density group, the differences between groups A and B or C were significant (q = 48.83, 46.22, respectively, P both < 0.05), the differences between groups B and C were insignificant (q = 1.74, P > 0.05). Pairwise comparisons of the sub-groups with different hyalocyte densities in groups A, B and C (comparisons of 2×10(7)/L and 1×10(8)/L, 2×10(7)/L and 5×10(8)/L, 2×10(7)/L and 2×10(7)/L, respectively), the differences were all significant (group A:q = -55.97, -65.66, -9.69, respectively; group B: q = -34.53, -57.41, -22.88, respectively; group C: q = -41.94, -63.19, -21.25, P all < 0.05). Furthermore, the regression analysis was performed between the hyalocyte density and the collage gel contraction rates in each group. The results showed that there was a positive correlation between the gel contraction rates of the co-culture collagen gel contraction system and its hyalocyte density (groups A, B, C: r = 0.919, 0.981, 0.937, respectively, P all < 0.05). Pairwise comparison of groups D and E, D and F, E and F by SNK-q test revealed q = 54.87, 49.33, 5.54, respectively, P all < 0.05.

CONCLUSION

Opticin is capable of regulating the contraction of bovine hyalocytes and RPE cells co-culture collagen gel.

A gene-networked gel matrix-supported lipid bilayer as a synthetic nucleus system

A spheroidal transgene-networked gel matrix was designed as a synthetic nucleus system. It was spheroidically manufactured using both advanced lithography and DNA nanotechnology. Stable Aqueorea coerulescens green fluorescent protein (AcGFP)-encoding gene cross-networks have been optimized in various parameters: the number of gene-networked gel (G-net-gel) spheroids, the concentration of a AcGFP plasmid in the scaffold, and the molar ratio between the X-DNA building blocks and the gene. It was then assessed that 800 units of the gene networked gel matrix at a 4000:1 molar ratio of X-DNA blocks and AcGFP gene components accomplished 20-fold enhanced in vitro protein expression efficiency for 36 h. Furthermore, once with lipid capping, it reproduced the natural nucleus system, demonstrating the 2-fold increased levels of messenger RNAs (mRNAs) relative to solution phase vectors.

Controlled release of dexamethasone from peptide nanofiber gels to modulate inflammatory response

New biomaterials that have the ability to locally suppress an immune response could have broad therapeutic use in the treatment of diseases characterized by acute or chronic inflammation or as a strategy to facilitate improved efficacy in cell or tissue transplantation. We report here on the preparation of a modular peptide amphiphile (PA) capable of releasing an anti-inflammatory drug, dexamethasone (Dex), by conjugation via a labile hydrazone linkage. This molecule self-assembled in water into long supramolecular nanofibers when mixed with a similar PA lacking the drug conjugate, and the addition of calcium salt to screen electrostatic repulsion between nanofibers promoted gel formation. These nanofiber gels demonstrated sustained release of soluble Dex for over one month in physiologic media. The Dex released from these gels maintained its anti-inflammatory activity when evaluated in vitro using a human inflammatory reporter cell line and furthermore preserved cardiomyocyte viability upon induced oxidative stress. The ability of this gel to mitigate the inflammatory response in cell transplantation strategies was evaluated using cell-surrogate polystyrene microparticles suspended in the nanofiber gel that were then subcutaneously injected into mice. Live animal luminescence imaging using the chemiluminescent reporter molecule luminol showed a significant reduction in inflammation at the site where particles were injected with Dex-PA compared to the site of injection for particles within a control PA in the same animal. Histological evidence suggested a marked reduction in the number of infiltrating inflammatory cells when particles were delivered within Dex-PA nanofiber gels, and very little inflammation was observed at either 3 days or 21 days post-implantation. The use of Dex-PA could facilitate localized anti-inflammatory activity as a component of biomaterials designed for various applications in regenerative medicine and could specifically be a useful module for PA-based therapies. More broadly, these studies define a versatile strategy for facile synthesis of self-assembling peptide-based materials with the ability to control drug release.

Thiolated xyloglucan: Synthesis, characterization and evaluation as mucoadhesive in situ gelling agent

The objective of present study was to enhance bioadhesive potential of xyloglucan by thiolation. Thiolation of xyloglucan was achieved with esterification with thioglycolic acid. Thiolated xyloglucan was characterized by NMR, DSC, and XRD analysis. Thiolated xyloglucan was determined to possess 4mmol of thiol groups/g of polymer by Ellman's method. Comparative evaluation of mucoadhesive property of ondansetron containing in situ gel system of xyloglucan and thiolated xyloglucan using sheep nasal mucosa revealed higher ex vivo bioadhesion time of thiolated xyloglucan as compared to xyloglucan. Improved mucoadhesive property of thiolated xyloglucan over the xyloglucan can be attributed to the formation of disulfide bond between mucus and thiolated xyloglucan. Ex vivo permeation study conducted using sheep nasal showed improved drug permeation in formulation based on thiolated xyloglucan. In conclusion, thiolation of xyloglucan improves its bioadhesion and drug permeation without affecting the resultant gel properties.

Enzymatic method for measuring starch gelatinization in dry products in situ

An enzymatic method based on hydrolysis of starch by amyloglucosidase and measurement of d-glucose released by glucose oxidase-peroxidase was developed to measure both gelatinized starch and hydrolyzable starch in situ of dried starchy products. Efforts focused on the development of sample handling steps (particle size reduction of dry samples followed by a unique mechanical resolubilization step) prior to the enzymatic hydrolysis using native and fully gelatinized flours of corn and rice. The new steps, when optimized, were able to maximize resolubilization of gelatinized/retrograded starch while minimizing solubilization of native starch in dried samples, thus effectively addressing issues of insusceptibility of retrograded starch and susceptibility of native starch to enzymatic attacks and eliminating the need to isolate starch from dry samples before using an enzymatic method. Various factors affecting these and other steps were also investigated, with the objectives to simplify the procedures and reduce errors. Results are expressed as the percentage of the total starch content. The proposed method, verified by measuring mixed samples of native and fully gelatinized flours of five grain species (corn, rice, barley, oat, and wheat) at different ratios, is simple, accurate, and reliable, with a relative standard deviation of less than 5%.

Incorporation of cell-adhesion peptides into collagen scaffolds promotes corneal epithelial stratification

The objective of this study was to examine the effects of cell-adhesion peptides incorporated into collagen scaffolds on corneal epithelial cell stratification. Peptides (YIGSR, YIGSRIKVAV, IKVAVYIGSR and negative control YISGR) were first chemically attached to dendrimers. The peptide-modified dendrimers were then used as collagen cross-linkers. This permitted the incorporation of the peptides into the bulk structure of the collagen gels. The amount of peptide incorporated into the collagen gels was determined by 125I radiolabelling to be between 0.064 and 6.4 microg/mg collagen for YIGSR, and between 0.1187 to 11.87 microg/mg collagen for YIGSRIKVAV and IKVAVYIGSR. Corneal epithelial cell monolayers were grown on the surface of the collagen scaffolds and then exposed to conditions that promoted stratification as a stratified epithelial layer is desired in a tissue-engineered cornea. It was found that all of the incorporated peptides promoted stratification of the cells with the exception of the negative control YISGR. A synergistic effect of the combined sequences from laminin was observed, with the orientation of the peptide sequences having a great impact on the ability of the materials to promote cell stratification.

Measuring binding of protein to gel-bound ligands using magnetic levitation

This paper describes the use of magnetic levitation (MagLev) to measure the association of proteins and ligands. The method starts with diamagnetic gel beads that are functionalized covalently with small molecules (putative ligands). Binding of protein to the ligands within the bead causes a change in the density of the bead. When these beads are suspended in a paramagnetic aqueous buffer and placed between the poles of two NbFeB magnets with like poles facing, the changes in the density of the bead on binding of protein result in changes in the levitation height of the bead that can be used to quantify the amount of protein bound. This paper uses a reaction-diffusion model to examine the physical principles that determine the values of rate and equilibrium constants measured by this system, using the well-defined model system of carbonic anhydrase and aryl sulfonamides. By tuning the experimental protocol, the method is capable of quantifying either the concentration of protein in a solution, or the binding affinities of a protein to several resin-bound small molecules simultaneously. Since this method requires no electricity and only a single piece of inexpensive equipment, it may find use in situations where portability and low cost are important, such as in bioanalysis in resource-limited settings, point-of-care diagnosis, veterinary medicine, and plant pathology. It still has several practical disadvantages. Most notably, the method requires relatively long assay times and cannot be applied to large proteins (>70 kDa), including antibodies. The design and synthesis of beads with improved characteristics (e.g., larger pore size) has the potential to resolve these problems.