Molecular Gel Research Articles

Cyano-modified molecular cage silica gel stationary phase: Multi-functional chromatographic performance by high-performance liquid chromatography

This study successfully prepared different loading levels of cyano-functionalized RCC3 molecular cage silica gel stationary phase (RCC3-CN@SiO2) through aldehyde-amine condensation reaction and subsequent modification strategies. Fourier transform infrared spectroscopy, thermogravimetric analysis, nitrogen adsorption-desorption, and scanning electron microscopy confirmed the successful synthesis of RCC3-CN@SiO2 chromatographic stationary phase. The research demonstrates that due to hydrophobic/hydrophilic interactions, π-π interactions, hydrogen bonding, and size-selective porous structure, the stationary phase effectively separates moderately polar and weakly polar compounds in reversed-phase liquid chromatography (RPLC) mode, exhibiting hydrophobic selectivity comparable to the commercial DaisoC18-RP columns. Additionally, the tertiary amine and cyanogen groups on the molecular cage surface enhance the interaction with polar compounds, successfully separating nucleosides, sulfonamides, amino acids, and sugars in hydrophilic interaction chromatography (HILIC) mode. Further applications in the separation analysis of acidic drugs, alkaline drugs, cinnamic acid natural products, and chiral compounds demonstrate the multifunctional chromatographic capabilities for diverse compound types. Compared to Unitary Diol commercial columns, the prepared stationary phase showed significant advantages in wide polarity range separation performance. Moreover, through nucleoside compound separation mode switching analysis, RCC3-CN@SiO2 stationary phase further validates its favorable performance in both RPLC and HILIC modes, demonstrating extensive potential applications in the field of analytical chemistry. Importantly, the stationary phase exhibits efficient separation of nucleoside compounds in pure water systems, aligning with the principles of green analysis.

Rheological analysis of network structure of raw natural rubber prepared by different processing techniques

The performance of raw natural rubber (NR) is dominated by its network structure, particular the levels of long chain branching (LCB) and entanglement. Here, three type of raw rubbers were prepared using different processing methods for commercial grade NRs. Linear and nonlinear viscoelastic behaviors, as well as stress relaxation, were analyzed to access their network structures. The third relative harmonic, phase angle, and first to second quarter-period integral ratio of stress curve were utilized as indicators for the nonlinearity of samples. By combining these values with flow activation energy and characteristic times, it can be confirmed that naturally coagulated NR showed higher elasticity than acid-coagulated NR due to high levels of LCB and entanglement, and hot air drying could lead to chain degradation. These findings correlated with molecular weight parameters, gel content and Mooney viscosity results. This research establishes a method for monitoring raw NR quality and predicting its properties.

Improved qualities of cod-rice dual-protein gel as affected by rice protein: Insight into molecular flexibility, protein interaction and gel properties

Blending plant-based proteins with animal-based proteins to achieve adequate dietary protein intake is a strategy to address dietary deficiencies in the elderly. This research systematically investigated the effect of the ratio of cod protein/rice protein (21:0, 21:1.5, 21:3, 21:4.5, 21:6, 21:7.5, and 21:9) on the gelation properties of dual-protein gels and the underlying dual-protein interaction mechanisms. The results indicated that the myosin heavy chain (MHC) of cod and the glutelin in rice protein are primarily linked by hydrogen bonds, particularly involving Tyr residues, as evidenced by molecular docking and fluorescence quenching results. The addition of rice protein in cod protein promoted α-helix transforming into β-sheet, β-turn and random coil of the original protein solution, which was significantly correlated with molecule flexibility increasing. The decrease in the dual-protein particle size, and rice protein uniformly distributed in a cod protein-based gel network, which promoted the compactness and density of the gel structure. It was found that the hardness and springiness of 21:6 cod-rice protein gel increased by 73.96% and 17.28% compared to single cod gel, respectively. This study provides theoretical basis to the mechanism of dual-protein interaction affecting gel properties from the molecular level.

Small molecular weight alginate gel porogen for the 3D bioprinting of microvasculature.

In order to recreate the complexity of human organs, the field of tissue engineering and regenerative medicine has been focusing on methods to build organs from the bottom up by assembling distinct small functional units consisting of a biomaterial and cells. This bottom-up engineering requires bioinks that can be assembled by 3D bioprinting and that permit fast vascularization of the construct to ensure survival of embedded cells. To this end, a small molecular weight alginate (SMWA) gel porogen is presented herein. Alginate is a biocompatible biomaterial, which can be easily converted into small porogen gels with the procedure reported in this article. The SMWA porogen is mixed with photo-crosslinkable hydrogels and leached from the hydrogel post-crosslinking to increase porosity and facilitate vascularization. As a proof of concept, this system is tested with the commonly used biomaterial Gelatin Methacryloyl (GelMA). The SMWA porogen-GelMA blend is proven to be bioprintable. Incubating the blend for 20min in a low concentration phosphate buffered saline and sodium citrate solution significantly reduces the remaining porogen in the hydrogel . The intent to completely leach the porogen from the hydrogel was abandoned, as longer incubation times and higher concentrations of phosphate and citrate were detrimental to endothelial proliferation. Nonetheless, even with remnants of the porogen left in the hydrogel, the created porosity significantly improves viability, growth factor signaling, vasculogenesis, and angiogenesis in 3D bioprinted structures. This article concludes that the usage of the SMWA porogen can improve the assembly of microvasculature in 3D bioprinted structures. This technology can benefit the bottom-up assembly of large scaffolds with high cell density through 3D bioprinting by improving cell viability and allowing faster vascularization.

Effects of glycation modifications of different glycosylating agents on the molecular structure and gel properties of sheep's hoof gelatin

In this study, we utilized sheep's hoof gelatin as a raw material to modify gelatin by non-enzymatic glycation reactions using five different monosaccharides (D-glucose, D-sorbose, D-fructose, D-ribose, and D-erythrose) and five different polysaccharides (pectin, inulin, carrageenan, xanthan gum, and konjac glucomannan) and comparatively analyzed the properties (rheological properties, textural properties, and thermal stability) of differently glycosylated sheep's hoof gelatin to determine the mechanism of different glycosylating agents on the molecular properties and gel performance of sheep's hoof gelatin. The results showed that the reactivity (DG value) and phase transition temperature (Td value) of gelatin modified with monosaccharide glycosylates were notably higher (p < 0.05) compared to those modified with polysaccharides, resulting in a micro-network structure with finer pore size. Conversely, polysaccharide glycosylation significantly enhanced the mechanical properties and rheological characteristics of gelatin (p < 0.05). The formation of a mosaic network structure in the polysaccharide-glycosylated gelatin group played a pivotal role in enhancing gel properties. Notably, the gel strength (584.62 ± 6.34 g), viscosity (η-value), and gel melting temperature (37.85 ± 0.20 °C) of the polysaccharide S-PEC were significantly higher than the other treatment groups (p < 0.05). This research not only provides a new perspective for modifying gelatin derived from sheep's hooves but also offers an important theoretical basis for the exploration and application of gelatin materials in the food industry.

Passion fruit peel-derived low-methoxyl pectin: De-esterification methods and application as a fat substitute in set yogurt

Passion fruit pectin, originally high methoxyl pectin, undergoes substantial conversion into low methoxyl pectin (LMP) through de-esterification. This de-esterification is significance for reducing the application of sugar in food, as calcium ions can replace excessive sugar during gel formation. In this study, LMPs derived from passion fruit pectin were prepared using four methods: low-temperature alkali, room temperature alkali, enzymatic, and dielectric barrier discharge plasma (DBD)-assisted enzyme (DBDE). The de-esterification conditions were optimized, leading to the selection of LMPs with a degree of esterification for the analysis of molecular weight, monosaccharide composition, and gel properties. The results revealed significant differences in the structure and properties of LMPs depending on the de-esterification method applied. The galacturonic acid content of LMPs significantly increased, with LMP from DBDE (LMP-DBDE) exhibiting the highest increase at 47.81 %. Additionally, the molecular weights of LMPs significantly decreased, with LMP-DBDE showing the smallest decrease. LMP-DBDE demonstrated higher apparent viscosity, thermal stability, and gel properties, facilitating the formation of gels. After 21 days of storage, 0.40 % LMP-DBDE yogurt showed no whey separation, significantly extending its shelf life. Therefore, LMP-DBDE exhibits potential as a fat substitute, combining the advantages of LMP with enhanced water-holding capacity, and presenting promising applications in low-fat dairy products.

Insight into the Stabilization Mechanism of Succinylation Modification on Black Bean Protein Gels: Molecular Conformation, Microstructure, and Gel Properties.

The objective of this work was to investigate the effect of succinylation treatment on the physicochemical properties of black bean proteins (BBPI), and the relationship mechanism between BBPI structure and gel properties was further analyzed. The results demonstrated that the covalent formation of higher-molecular-weight complexes with BBPI could be achieved by succinic anhydride (SA). With the addition of SA at 10% (v/v), the acylation of proteins amounted to 92.53 ± 1.10%, at which point there was a minimized particle size of the system (300.90 ± 9.57 nm). Meanwhile, the protein structure was stretched with an irregular curl content of 34.30% and the greatest processable flexibility (0.381 ± 0.004). The dense three-dimensional mesh structure of the hydrogel as revealed by scanning electron microscopy was the fundamental prerequisite for the ability to resist external extrusion. The thermally induced hydrogels of acylated proteins with 10% (v/v) addition of SA showed excellent gel elastic behavior (1.44 ± 0.002 nm) and support capacity. Correlation analysis showed that the hydrogel strength and stability of hydrogels were closely related to the changes in protein conformation. This study provides theoretical guidance for the discovery of flexible proteins and their application in hydrogels.

Microstructure Evolution of Reactive Polyurethane Films During In Situ Polyaddition and Film-Formation Processes.

Due to the advantages of low energy consumption, no air and water pollutions, the reactive polyurethane films (RPUFs) are replacing the solvated and waterborne PUFs nowadays, which significantly promotes the green and low-carbon production of PU films. However, the microstructure evolution and in situ film-formation mechanism of RPUFs in solvent-free media are still unclear. Herein, according to time-temperature equivalence principle, the in situ polyaddition and film-formation processes of RPUFs generated by the typical polyaddition of diisocyanate terminated prepolymer (component B) and polyether glycol (component A) are thoroughly investigated at 25 °C. According to the temporal change of viscosity, the RPUFs gradually transfer from liquid to gel and finally to solid state. Further characterizing the molecular weight, hydrogen bonds, crystallinity, gel content, and phase images, the polyaddition and film-formation processes can be divided into three stages as 1) chain extension and microcrystallization; 2) gelation and demicrocrystallization; 3) microphase separation and film-formation. This work promotes the understanding of the microstructure evolution and film-formation mechanism of RPUFs, which can be used as the theoretical guidance for the controllable preparation of high-performance products based on RPUFs.

Development of CDK12 as a Cancer Therapeutic Target and Related Inhibitors.

Cyclin-dependent Kinase 12 (CDK12) is a Cyclin-dependent Kinase (CDK) that plays a crucial role in various biological processes, including transcription, translation, mRNA splicing, cell cycle regulation, and DNA damage repair. Dysregulation of CDK12 has been implicated in tumorigenesis, and genetic alterations affecting CDK12 have been identified in multiple cancer types, including breast cancer, ovarian cancer, gastric cancer, and prostate cancer. Numerous studies have demonstrated that suppression of CDK12 expression effectively inhibits tumor growth and proliferation, underscoring its significance as a cancer biomarker and a potential therapeutic target in cancer treatment. A thorough comprehension of CDK12 is expected to significantly enhance the advancement of novel approaches for the treatment and prevention of cancer. In recent times, endeavors have been undertaken to formulate targeted inhibitors for CDK12, such as PROTAC and molecular gel degraders. Concurrently, investigations have been conducted on the combined utilization of CDK12 small molecule inhibitors and immunotherapy as a potential strategy. This paper examines the diverse functions of CDK12 in the modulation of gene expression and its implications in human tumors. Specifically, it explores the recently uncovered roles of CDK12 kinases in various cellular processes, emphasizing the potential of CDK12 as a viable therapeutic target for the management of human tumors. Furthermore, this review provides an up-to-- date account of the advancements made in utilizing CDK12 in tumor therapy.

Alkyl–π Functional Molecular Gels: Control of Elastic Modulus and Improvement of Electret Performance

AbstractThe development of optoelectronically‐active soft materials is drawing attention to the application of soft electronics. A room‐temperature solvent‐free liquid obtained by modifying a π‐conjugated moiety with flexible yet bulky alkyl chains is a promising functional soft material. Tuning the elastic modulus (G′) is essential for employing optoelectronically‐active alkyl–π liquids in deformable devices. However, the range of G′ achieved through the molecular design of alkyl–π liquids is limited. We report herein a method for controlling G′ of alkyl–π liquids by gelation. Adding 1 wt % low‐molecular‐weight gelator formed the alkyl–π functional molecular gel (FMG) and increased G′ of alkyl–π liquids by up to seven orders of magnitude while retaining the optical properties. Because alkyl–π FMGs have functional π‐moieties in the gel medium, this new class of gels has a much higher content of π‐moieties of up to 59 wt % compared to conventional π‐gels of only a few wt %. More importantly, the gel state has a 23 % higher charge‐retention capacity than the liquid, providing better performance in deformable mechanoelectric generator‐electret devices. The strategy used in this study is a novel approach for developing next‐generation optoelectronically‐active FMG materials.

Alkyl-π Functional Molecular Gels: Control of Elastic Modulus and Improvement of Electret Performance.

The development of optoelectronically-active soft materials is drawing attention to the application of soft electronics. A room-temperature solvent-free liquid obtained by modifying a π-conjugated moiety with flexible yet bulky alkyl chains is a promising functional soft material. Tuning the elastic modulus (G') is essential for employing optoelectronically-active alkyl-π liquids in deformable devices. However, the range of G' achieved through the molecular design of alkyl-π liquids is limited. We report herein a method for controlling G' of alkyl-π liquids by gelation. Adding 1 wt % low-molecular-weight gelator formed the alkyl-π functional molecular gel (FMG) and increased G' of alkyl-π liquids by up to seven orders of magnitude while retaining the optical properties. Because alkyl-π FMGs have functional π-moieties in the gel medium, this new class of gels has a much higher content of π-moieties of up to 59 wt % compared to conventional π-gels of only a few wt %. More importantly, the gel state has a 23 % higher charge-retention capacity than the liquid, providing better performance in deformable mechanoelectric generator-electret devices. The strategy used in this study is a novel approach for developing next-generation optoelectronically-active FMG materials.

Natural rubber – Increasing diversity of an irreplaceable renewable resource

This paper discusses the importance of introducing domestic natural rubber production and presents the rediscovery of a rubber-producing species, Scorzonera tau-saghyz or “mountain gum”, originally discovered in 1929 on the Karatau mountains in Kazakhstan. This plant could potentially also be cultivated in the U.S. In this exploratory work, roots (2–5 years old) were harvested on June 16, 2021 from wild strands in the Karatau mountains, Kumantas ridge, and Saraba, Kazakhstan, and processed at the Ohio State University. The rubber extraction method was based on an indigenous method in Kazakhstan to make natural chewing gum. Water extraction followed by purification yielded 16.2 wt% rubber from the dry roots, in comparison with 4–8 wt% from most rubber dandelion (Taraxacum kok-saghyz) plants, also a potential domestic rubber producing plant. High-resolution size exclusion chromatography was used to analyze rubber samples. The molecular weights and gel and oligomer contents were very similar to the rubber from Hevea brasiliensis, the current commercial source of natural rubber. More detailed investigations of this very interesting rubber-producing plant are in progress.

Methods of changing low molecular weight gel properties through gelation kinetics.

Low molecular weight gels continue to attract notable interest, with many potential applications. However, there are still significant gaps in our understanding of these systems and the correlation between the pre-gel and final gel states. The kinetics of the gelation process plays a crucial role in the bulk properties of the hydrogel and presents an opportunity to fine-tune these systems to meet the requirements of the chosen application. Therefore, it is possible to use a single gelator for multiple applications. This review discusses four ways to modify the pre-gelled structures before triggering gelation. Such modifications can enhance the material's intended performance, which may result in significant advancements in high-tech areas, such as drug delivery, cell culturing, electronics, and tissue engineering.

Kinetic studies and bioremediation potential of chromate reductase-characterized Aspergillus flavus from tannery effluent

Chromium is among the major environmental pollutants endangering the health of all living things, including humans. Conventional methods for chromium detoxification are expensive, so bioremediation using fungi as potential agents for the detoxification of chromium is justified. This study aims to investigate chromium-resistant fungi capable of reducing or transforming Cr (VI) to less toxic Cr (III) from tannery effluents. The fungi were isolated from tannery wastewater and identified using 16S rRNA gene sequencing. Chromate reductase was isolated from pure fungal isolate and purified using molecular weight estimation and gel filtration chromatography. Aspergillus flavus, in an interesting turn of events, demonstrated 97% chromate reduction. The chromate reductase from Aspergillus flavus has KM of 0.015 mM and a Vmax of 0.25 mol/min. Furthermore, the enzyme's activity was constant at its peak at pH 7.0 and 50 oC, with a single band displaying a molecular weight of 44 kDa for a pure protein. The data suggest that A. flavus can be a good candidate for the detoxification of Cr (VI) in industrial effluents. The efficiency of which can be attributed to the action of chromate reductase in the A. flavus.

Constructing hierarchically elongated porous structure in ultrathin ultrahigh molecular weight polyethylene membrane: Achieving high selectivity with remained permeability

Anisotropic pores with a high aspect ratio exhibit higher permeability as well as selectivity than circular pores. Herein, highly selective porous membranes exhibiting elongated slit-like pores and disk-like interlayer large pores are fabricated successfully by biaxial stretching and further constrained uniaxial stretching of ultrahigh molecular weight polyethylene gel films. The thickness and the surface roughness of the porous membrane decrease, and the pore size distribution become narrow during biaxial stretching, while the porous structure become elongated during constrained uniaxial stretching. The thickness decreases from 173.23 μm to 2.33 μm, which reduces the resistance to water passage and then increases the water permeability from approximately 540 L/ (m2 h bar) to 780 L/ (m2 h bar). Due to the presence of mineral oil, the porosity is maintained and even high ratios of constrained uniaxial stretching do not close the pores. The elongation of the porous structure resulted in a significant reduction of the membrane pore size. At a total stretching ratio of 144 times, the pore size of the porous membrane with only biaxial stretching is 0.098 μm, while that of the porous membrane with biaxial stretching and further constrained uniaxial stretching is 0.048 μm. The separation accuracy and stability of the porous membrane improve distinctly, ascribing that the small pore size can reject small particles and prevent the particles from entering the membrane. This study provides one novel strategy to regulate the porous structure of porous polymer membranes for improving the separation efficiency.

Permeability reduction techniques: Plain and fiber HPAM gels in fractured cores

The aim of this study is to investigate how fibers influence the ability of polymer gels to resist washing out from fractures. For this purpose, synthetic and mineral wool fibers were integrated into polymer gels. These fiber-gels were compared to plain gels using bottle tests, viscosity measurements, and fractured core flooding experiments.The bottle tests show no effect of 13-mm-long synthetic fibers on gel strength. However, inside a constricted fracture, the polymer-synthetic fiber gel exhibited 8.4 times higher resistance to the flow of brine compared to the plain gel. This is explained by the retention of the fibers at the constriction point. In low salinity brine, mineral wool fibers allowed a substantial improvement in gel strength, while, at the same time, a reduction in the concentration of chemicals by 40% was made possible.Furthermore, with the addition of 0.6 wt.% mineral wool fibers, the viscosity of the 0.3 wt.% polymer gel increased from 560.5 to 106,920 cp. In fact, in a 1-mm-wide fracture, a gel containing 0.3 wt.% polymer and 0.6 wt.% mineral wool fiber achieved a post-flush pressure gradient that was 58 times higher than a 0.75 wt.% plain polymer gel. Unfortunately, the choice of a makeup brine with an increased salinity resulted in the deterioration of fiber-gel strength. Nonetheless, a substantial improvement of gel strength can be achieved by adding 0.6 wt.% mineral wool fibers, even if the salinity is as high as 143 g/L. Moreover, in experiments in which the permeability of the adjacent matrix was very low, 0.018 mD, a gel of 0.3 wt.% polymer and 0.6 wt.% mineral wool fiber prepared in 242.6 g/L brine, was still superior to a 0.75 wt.% plain gel prepared in low salinity brine.Experimentation with large fracture widths of 2.55 mm and 4 mm was also done to confirm gel effectiveness. For example, a gel of 0.3 wt.% polymer and 0.6 wt.% mineral wool fiber, prepared in 14 g/L brine, provided a 1.46 times higher post-flush pressure gradient in a 2.55-mm-wide fracture, as compared to that of a 0.75 wt.% plain polymer low salinity gel in a 1-mm-wide fracture. With an increase in the salinity, to 234.6 g/L, of the makeup brine used with a fiber-gel, the resistance to the flow of brine in a 2.55-mm-wide fracture became comparable to that of a plain gel in a 1-mm-wide fracture. In a 4-mm-wide fracture, a gel with 0.3 wt.% polymer prepared in 234.6 g/L brine and one of 0.5 wt.% polymer prepared in 14 g/L brine, each with 0.6 wt.% mineral wool fiber, provided maximal post-flush pressure gradients equal to 12–14 psi/ft. This is the same range usually expected from a 0.5 wt.% relatively low molecular weight plain polymer gel in a 1-mm-wide fracture.Although, fibers improved the ability of gels to resist washing out from fractures, in a 4-mm-wide fracture such a fiber-gel could not provide notable resistance to the flow of brine with an increase in the superficial flow velocity higher than 1,000 ft/d. Discovering formulas that would increase the resistance of gels to being washed out of wide fractures must continue.

Molecular design, gel properties, and anti-settling ability with natural rosin-based sulfonamide compounds regulated by conjugation

The design of compounds with excellent controllable weak forces is of great significance to solve current industrial problems. Herein, three natural rosin-based sulfonamide compounds (i.e., dehydroabietyl-based benzene sulfonamide (DBS-1); dehydroabietyl-based benzyl sulfonamide (DBS-2), and dehydrofiranic acid-based p-toluene sulfonamide (DBS-3)) were designed and synthesized by regulating the conjugation of sulfamide, carbonamide, and benzene. Organogels with rod-like, spherical, and layered morphologies were formed by π–π stacking and one-dimensional hydrogen bonding in the absence of an external driving force. Rheological studies emphasized the mechanical strength of these organogels, and gel three-dimensional networks at the nano- and micron-scales can effectively capture six volatile organic solvents. Notably, the presence of conjugation can effectively regulate the dynamic and static equilibrium of organogels to construct stable supermolecular assemblies. DBS-1, which contained abundant conjugated structures and weak intermolecular forces, exhibited amazing anti-settling ability in synthetic oil-based drilling fluids, with a static sedimentation factor of 0.512. Thus, industrial problems such as barite settlement can be solved by using DBS-1 as an additive agent. This report provides inspiration for the effective design of natural anti-settling agents.

Study on low methoxyl pectin (LMP) with varied molecular structures cross-linked with calcium inducing differences in the gel properties

The gel properties of pectin are significantly connected with its molecular structure. In this paper, we investigated the relationship between low methoxyl pectin (LMP) molecular structure and gel strength in the same degree of esterification (DE) range. LMP with DE of 31% ± 2% was prepared from citrus peels by acid, alkaline, enzymatic, and citric acid/sodium citrate solution methods. And based on data from monosaccharide composition, Mw, and NMR spectroscopy, the proportion of structural regions was speculated. The result revealed that C-LMP (pectin de-esterified by citric acid/sodium citrate solution method) was a highly branched macromolecular polysaccharide with short HG and enriched RG-I, with HG and RG-I proportions of 19.37% and 76.96%. According to the gel property investigation, of all the LMP samples, A-LMP-0.7 (pectin de-esterified by acid method at pH 0.7), which possessed lengthy HG and enriched RG-I domain, exhibited the best gel strength. C-LMP, A-LMP-0.5 (pectin de-esterified by acid method at pH 0.5), and B-LMP (pectin de-esterified by alkaline) failed to form a complete gel due to the low HG linearity, sparse RG-I and low Mw, respectively.

Clinical Evaluation of a Novel Combination of Sodium Hypochlorite/Amino Acid and Cross-linked Hyaluronic Acid Adjunctive to Non-surgical Periodontal Treatment: A Case Series.

The adjunctive subgingival application of sodium hypochlorite/amino acid and a mixture of natural and cross-linked hyaluronic acid gels (high molecular weight) has been recently proposed as a novel modality to enhance the outcomes of non-surgical periodontal therapy. The aim of this prospective case series was to evaluate the clinical outcomes obtained following the subgingival application of a combination of sodium hypochlorite/amino acid and a mixture of natural and cross-linked hyaluronic acid (high molecular) gels in conjunction with non-surgical periodontal therapy. Twenty-one systemically healthy, non-smoking patients diagnosed with stage II-III, grade A/B periodontitis underwent full-mouth subgingival debridement (SD) performed with ultrasonic and hand instruments. All sites with probing depths (PD) ≥ 4 mm were treated with additional repeated (i.e., 2-3 times) instillation of sodium hypochlorite/amino acid gel in the periodontal pockets prior to and during SRP. Following mechanical debridement, a mixture of natural and cross-linked hyaluronic acid (high molecular) gel was applied in the pockets. The primary outcome variable was PD reduction; changes in clinical attachment level (CAL) and bleeding on probing (BOP) were the secondary outcomes. The clinical parameters were assessed at baseline, 3 and 6 months after therapy. Compared to baseline, a statistically significant mean reduction of PD values was obtained after 3 and 6 months, amounting to 2.6 ± 0.4 mm, and 2.9 ± 0.4 mm, respectively (p < 0.001). Mean CAL gain measured 2.3 ± 0.5 mm at 3 months and 2.6 ± 0.5 mm at 6 months in comparison to baseline (p < 0.001). Mean reduction of BOP values was 54.9 ± 16.9 % at 3 months and 65.6 ± 16.4 % at 6 months (p < 0.001). The number of moderate pockets (4-5 mm) decreased from 1808 at baseline to 274 at the 6-month evaluation, and the number of deep (≥ 6 mm) pockets dropped from 319 to 3, respectively. The combination of sodium hypochlorite/amino acid and a mixture of natural and cross-linked hyaluronic acid (high molecular) adjunctive to subgingival debridement may represent a valuable approach to improve the outcomes of non-surgical periodontal treatment.

Modulus self-recovery phenomenon after shearing of natural rubber based on supramolecular network aggregation structure

Natural rubber (NR) and isoprene rubber (IR) exhibit a similar shear-thinning phenomenon, in which NR has the inverse ‘S′ shape stress-strain curve and IR has the yield stress-strain curve. Different from IR, NR exhibits the modulus self-recovery phenomenon after shearing. The experimental data showed that the 300% modulus of NR could recover 41.84% after it was sheared 5 times and stored for 30 days. The tensile strength would even recover completely. The modulus self-recovery efficiency (MSRE) would decrease with increasing shearing times. A mechanism model of the structure self-healing efficiency (SSHE) was proposed based on the supramolecular network aggregation structure (SNAS) formed by the weak valence bond of the non-rubber components (NRCs) at the terminal group of the NR macromolecular chains. The mechanical shearing force would break the SNAS of NR and the short molecular chains would fall off from the SNAS. The dropped shorted molecular chains of NR would re-enter the SNAS under the hydrogen-bond interaction generated by the NRCs after storing for a while, increasing the molecular weight and improving the mechanical properties. The 300% modulus would recover partly and the tensile strength might exceed the initial value if the NR was sheared slightly. On the contrary, as the same molecular structure without NRCs, IR did not show any modulus self-recovery phenomenon after shearing. Except it was confirmed by the increased molecular weight and gel content after shearing and storing, this mechanism model could be confirmed by the de-structured transesterification natural rubber (TENR) which did not exhibit the modulus self-recovery phenomenon anymore after removing the NRCs, such as proteins and phospholipids.