Thermo-responsive gels based on supramolecular assembly of an amidoamine and citric acid

One-step fabrication of flexible polyamide@Ag-dodecanethiol membranes for highly sensitive SERS detection of thiram

The surface-enhanced Raman scattering (SERS) is an effective spectral technology based on Raman scattering, but in practice, the commonly used SERS substrates suffer from low sensitivity and poor stability. In order to overcome these limitations, the SERS substrates were prepared from hydrophobic modification of dodecanethiol (C12) coupled with a flexible substrate, which was then used for pesticides detection in water. A flexible PA@Ag-C12 substrate with surface functionalization has been obtained. This work aims to investigate the self-assembly of Ag NPs modified with C12 onto polyamide (PA) membranes. Initially, transmission electron microscopy and scanning electron microscopy were used to analyze the substrate's morphology. Then with the help of an energy-dispersive spectrometer, sulfur content of C12-modified Ag NPs was analyzed. In order to determine the hydrophobicity of the modified Ag NPs, the contact angle was used. The results indicate that the gap between Ag NPs on PA membrane can be effectively controlled in order to prevent Ag NPs from aggregating. Furthermore, the finite-difference time-domain analysis indicated that the PA@Ag-C12 substrate exhibited a stronger electromagnetic enhancement effect than the PA@Ag substrate. By reducing NPs gaps on the PA membrane, the number of 'hot spots' increased, and the SERS performance of the substrate was improved as a result. According to the results of this study, this method can greatly reduce the manufacturing costs and time costs of the SERS substrate while maintaining the original uniformity. The SERS performance of PA@Ag-C12 was found to be three orders of magnitude better than that of PA@Ag direct self-assembled substrate, and the detection limit for Rhodamine 6G (R6G) was approximately 8.47 × 10-14M. On the basis of the PA@Ag-C12 substrate, thiram is detectable at a detection limit of 5.88 × 10-11M with a high degree of sensitivity and repeatability.

Review of the Perspectives and Study of Thermo-Responsive Polymer Gels and Applications in Oil-Based Drilling Fluids

Thermoresponsive polymer gels are a type of intelligent material that can react to changes in temperature. These materials possess excellent innovative properties and find use in various fields. This paper systematically analyzes the methods for testing and regulating phase transition temperatures of thermo-responsive polymer gels based on their response mechanism. The report thoroughly introduces the latest research on thermo-responsive polymer gels in oil and gas extraction, discussing their advantages and challenges across various environments. Additionally, it elucidates how the application limitations of high-temperature and high-salt conditions can be resolved through process optimization and material innovation, ultimately broadening the scope of application of thermo-responsive polymer gels in oil and gas extraction. The article discusses the technological development and potential applications of thermo-responsive polymer gels in oil-based drilling fluids. This analysis aims to offer researchers in the oil and gas industry detailed insights into future possibilities for thermo-responsive polymer gels and to provide helpful guidance for their practical use in oil-based drilling fluids.

Novel Natural Carrier-Free Self-Assembled Nanoparticles for Treatment of Ulcerative Colitis by Balancing Immune Microenvironment and Intestinal Barrier

Ulcerative colitis (UC) is a chronic inflammatory illness affecting the colon and rectum, with current treatment methods being unable to meet the clinical needs of ulcerative colitis patients. Although nanomedicines are recognized as promising anti-inflammatory medicines, their clinical application is limited by their high cost and unpredictable safety risks. This study reveals that two natural phytochemicals, berberine (BBR) and hesperetin (HST), self-assemble directly to form binary carrier-free multi-functional spherical nanoparticles (BBR-HST NPs) through noncovalent bonds involving electrostatic interactions, π-π stacking, and hydrogen bonding. Because of their synergistic anti-inflammatory activity, berberine-hesperetin nanoparticles (BBR-HST NPs) exhibit significantly better therapeutic effects on UC and inhibitory effects on inflammation than BBR and HST at the same dose by regulating the immune microenvironment and repairing the damaged intestinal barrier. Furthermore, BBR-HST NPs exhibit good biocompatibility and biosafety. Thus, this study proves the potential of novel natural anti-inflammatory nanoparticles as therapeutic agents for UC, which could promote the progress of drug development for UC and eventually benefit patients who suffering from it.

Stimuli-responsive viscosity modifiers

Stimuli responsive viscosity modifiers entail an important class of materials which allow for smart material formation utilizing various stimuli for switching such as pH, temperature, light and salinity. They have seen applications in the biomedical space including tissue engineering and drug delivery, wherein stimuli responsive hydrogels and polymeric vessels have been extensively applied. Applications have also been seen in other domains like the energy sector and automobile industry, in technologies such as enhanced oil recovery. The chemistry and microstructural arrangements of the aqueous morphologies of dissolved materials are usually sensitive to the aforementioned stimuli which subsequently results in rheological sensitivity as well. Herein, we overview different structures capable of viscosity modification as well as go over the rheological theory associated with classical systems studied in literature. A detailed analysis allows us to explore correlations between commonly discussed models such as molecular packing parameter, tube reptation and stress relaxation with structural and rheological changes. We then present five primary mechanisms corresponding to stimuli responsive viscosity modification: (i) packing parameter modification via functional group conditioning and (ii) via dynamic bond formation, (iii) mesh formation by interlinking of network nodes, (iv) viscosity modification by chain conformation changes and (v) viscosity modification by particle jamming. We also overview several recent examples from literature that employ the concepts discussed to create novel classes of intriguing stimuli responsive structures and their corresponding rheological properties. Furthermore, we also explore systems that are responsive to multiple stimuli which can provide enhanced functionality and versatility by providing multi-level and precise actuation. Such systems have been used for programmed site-specific drug delivery.

pH- and temperature-responsive supramolecular assemblies with highly adjustable viscoelasticity: a multi-stimuli binary system

Stimuli-responsive materials are increasingly needed for the development of smart electronic, mechanical, and biological devices and systems relying on switchable, tunable, and adaptable properties. Herein, we report a novel pH- and temperature-responsive binary supramolecular assembly involving a long-chain hydroxyamino amide (HAA) and an inorganic hydrotrope, boric acid, with highly tunable viscous and viscoelastic properties. The system under investigation demonstrates a high degree of control over its viscosity, with the capacity to achieve over four orders of magnitude of control through the concomitant manipulation of pH and temperature. In addition, the transformation from non-Maxwellian to Maxwellian fluid behavior could also be induced by changing the pH and temperature. Switchable rheological properties were ascribed to the morphological transformation between spherical vesicles, aggregated/fused spherical vesicles, and bicontinuous gyroid structures revealed by cryo-TEM studies. The observed transitions are attributed to the modulation of the head group spacing between HAA molecules under different pH conditions. Specifically, acidic conditions induce electrostatic repulsion between the protonated amino head groups, leading to an increased spacing. Conversely, under basic conditions, the HAA head group spacing is reduced due to the intercalation of tetrahydroxyborate, facilitated by hydrogen bonding.

An Overview of the Supramolecular Systems for Gene and Drug Delivery in Tissue Regeneration

Tissue regeneration is a prominent area of research, developing biomaterials aimed to be tunable, mechanistic scaffolds that mimic the physiological environment of the tissue. These biomaterials are projected to effectively possess similar chemical and biological properties, while at the same time are required to be safely and quickly degradable in the body once the desired restoration is achieved. Supramolecular systems composed of reversible, non-covalently connected, self-assembly units that respond to biological stimuli and signal cells have efficiently been developed as preferred biomaterials. Their biocompatibility and the ability to engineer the functionality have led to promising results in regenerative therapy. This review was intended to illuminate those who wish to envisage the niche translational research in regenerative therapy by summarizing the various explored types, chemistry, mechanisms, stimuli receptivity, and other advancements of supramolecular systems.

Supramolecular dynamic binary complexes with pH and salt-responsive properties for use in unconventional reservoirs

Hydraulic fracturing of unconventional reservoirs has seen a boom in the last century, as a means to fulfill the growing energy demand in the world. The fracturing fluid used in the process plays a substantial role in determining the results. Hence, several research and development efforts have been geared towards developing more sustainable, efficient, and improved fracturing fluids. Herein, we present a dynamic binary complex (DBC) solution, with potential to be useful in the hydraulic fracturing domain. It has a supramolecular structure formed by the self-assembly of low molecular weight viscosifiers (LMWVs) oleic acid and diethylenetriamine into an elongated entangled network under alkaline conditions. With less than 2 wt% constituents dispersed in aqueous solution, a viscous gel that exhibits high viscosities even under shear was formed. Key features include responsiveness to pH and salinity, and a zero-shear viscosity that could be tuned by a factor of ~280 by changing the pH. Furthermore, its viscous properties were more pronounced in the presence of salt. Sand settling tests revealed its potential to hold up sand particles for extended periods of time. In conclusion, this DBC solution system has potential to be utilized as a smart salt-responsive, pH-switchable hydraulic fracturing fluid.

pH-responsive viscoelastic supramolecular viscosifiers based on dynamic complexation of zwitterionic octadecylamidopropyl betaine and triamine for hydraulic fracturing applications

Viscosity modifying agents are one of the most critical components of hydraulic fracturing fluids, ensuring the efficient transport and deposition of proppant into fissures. To improve the productivity index of hydraulic fracturing processes, better viscosifiers with a higher proppant carrying capacity and a lower potential of formation damage are needed. In this work, we report the development of a novel viscoelastic system relying on the complexation of zwitterionic octadecylamidopropyl betaine (OAPB) and diethylenetriamine (DTA) in water. At a concentration of 2 wt%, the zwitterionic complex fluid had a static viscosity of 9 to 200 poise, which could be reversibly adjusted by changing the suspension pH. The degree of pH-responsiveness ranged from 10 to 27 depending on the shear rate. At a given concentration and optimum pH value, the zwitterionic viscosifiers showed a two-orders-of-magnitude reduction in settling velocity of proppant compared to polyacrylamide solution (slickwater). By adjusting the pH between 4 and 8, the networked structure of the gel could be fully assembled and disassembled. The lack of macromolecular residues at the dissembled state can be beneficial for hydraulic fracturing application in avoiding the permeation damage issues encountered in polymer and linear-gel-based fracturing fluids. The reusability and the unnecessary permanent breakers are other important characteristics of these zwitterionic viscosifiers.

Viscosity modifying agents are one of the most critical components of hydraulic fracturing fluids, ensuring the efficient transport and deposition of proppant into fissures.

Morphological Manipulation of DNA Gel Microbeads with Biomolecular Stimuli

Hydrogels are essential in many fields ranging from tissue engineering and drug delivery to food sciences or cosmetics. Hydrogels that respond to specific biomolecular stimuli such as DNA, mRNA, miRNA and small molecules are highly desirable from the perspective of medical applications, however interfacing classical hydrogels with nucleic acids is still challenging. Here were demonstrate the generation of microbeads of DNA hydrogels with droplet microfluidic, and their morphological actuation with DNA strands. Using strand displacement and the specificity of DNA base pairing, we selectively dissolved gel beads, and reversibly changed their size on-the-fly with controlled swelling and shrinking. Lastly, we performed a complex computing primitive-A Winner-Takes-All competition between two populations of gel beads. Overall, these results show that strand responsive DNA gels have tantalizing potentials to enhance and expand traditional hydrogels, in particular for applications in sequencing and drug delivery.

Single network double cross-linker (SNDCL) hydrogels with excellent stretchability, self-recovery, adhesion strength, and conductivity for human motion monitoring

Hydrogels, as a kind of soft materials, are good candidates for smart skin-like materials. A double network is usually fabricated to improve the mechanical properties of hydrogels, and involves two different kinds of networks. In this work, a novel strategy for preparing single network double cross-linker (SNDCL) hydrogels was proposed and the prepared hydrogels exhibited excellent mechanical properties, including stretchability, compressibility, self-recovery, adhesion, shape memory and mechanical strength. N,N'-Methylenebisacrylamide forms covalent bonds with the network, while citric acid can form multiple weak interactions due to the polycarboxylic structure. This improves the tensile properties (6564%) and compressive properties of the hydrogel, and the hydrogels also exhibit long-lasting self-adhesion ability on various substrates. In addition, the hydrogels with multiple properties can be used as flexible strain sensors, allowing the monitoring of body movements. The hydrogels can hopefully be used in wearable electronic sensor devices and for healthcare monitoring.

Natural Berberine-Based Chinese Herb Medicine Assembled Nanostructures with Modified Antibacterial Application

The abuse of traditional antibiotics has caused a series of health problems including antimicrobial resistance, which threatens human health. Therefore, searching for broad sources of antimicrobial agents and developing multidimensional strategies to combat bacterial infections are urgent. Here, we reported two natural self-assembling modes between berberine (BBR) and flavonoid glycosides: nanoparticles (NPs) and nanofibers (NFs), which were both mainly governed by electrostatic and hydrophobic interactions. These two nanostructures exhibited different antibacterial properties from BBR. NPs showed significantly enhanced bacteriostatic activity, whereas NFs displayed a much weaker effect than BBR. The distinguishing properties can be attributed to the different spatial configurations and self-assembly processes of NPs and NFs. Flavonoid glycosides and BBR first formed a one-dimensional complex unit and subsequently self-assembled into three-dimensional nanostructures. With the hydrophilic glucuronic acid toward the outside, NPs exhibited stronger affinity to bacteria, thereby inducing the collapse of the bacteria population and the decrease in biofilm. In addition, in vitro hemolysis tests, cytotoxicity tests, and in vivo zebrafish toxicity evaluation showed that the obtained self-assemblies had good biocompatibility. This supramolecular self-assembly strategy can be applied to construct other nanoscale antibacterial drugs and thus provides weapons for the development of self-delivering drugs in bacterial infection treatment.

A mixed ligand approach towards lanthanide-based gels using citric acid as assembler ligand: white light emission and environmental sensing

Fine tuning the optical properties of lanthanide-based gels using low molecular weight gelators has several advantages over the polymeric gelator analogues. Herein, we have prepared a lanthanide-based gel using low molecular weight citric acid as the assembler ligand and the optical properties of the gel were fine-tuned, utilizing a mixed ligand approach, enabling white light emission and environmental sensing (pH and temperature). The coligand utilized in the study was 4'-(4-bromophenyl)-2,2':6',2''-terpyridine. The resultant mixed-ligand gel exhibited green and red emissions in the presence of Tb(iii) ions and Eu(iii) ions, respectively. White light emission was achieved, with CIE coordinates (0.33, 0.32), in the bimetallic Tb/Eu metallogel formed by the precise control over Tb/Eu ratio. The correlated color temperature (CCT) for white-light-emitting gel was calculated, and the value of 5473 K suggests that the system generates cool white light. While most of the reported low molecular weight gelators exhibit on-off responses to stimulus at a particular value, the present system is capable of gradually monitoring changes for stimuli such as pH and temperature over a wide range (pH from 4-11 and temperature from 20 to 70 °C). The unique design strategy of the gel and the characteristic physicochemical properties of the lanthanide ions resulted in the unprecedented ability of the system to monitor changes in environmental stimuli over a considerable range.