A new training model using the self-healing properties of supramolecular hydrogels for endoscopic combined intrarenal surgery

The combination of hydronephrosis formation, ureteroscopic imaging, and ultrasound delineation has not been included in any non-biological training model of percutaneous nephrolithotomy or endoscopic combined intrarenal surgery. We aimed to develop a realistic kidney phantom using the self-healing properties of supramolecular hydrogels for percutaneous nephrolithotomy and endoscopic combined intrarenal surgery and evaluate its suitability as a training model.Expert and resident urologists performed ultrasound-guided renal pelvic punctures and flexible ureteroscopies for endoscopic combined intrarenal surgery using a training model. Subsequently, the training model was evaluated using a 17-item Likert scale questionnaire (range, 1-5 points). After being filled with carrageenan, the collecting system was inflated, and the relationship between the collecting system volume and collecting system pressure was determined. The durability of the model was verified by repeatedly inserting a 16-Fr access sheath. Five novices and seven urology experts performed the procedure. The mean questionnaire score was 4.25 (standard deviation, 0.37). The model was able to hold 50 mL of air, and the pressure in the collecting system ranged from 6 to 33 mmHg. Repeated punctures were possible even when a 16-Fr access sheath was inserted. Our new training model included the self-healing properties of supramolecular hydrogels, which are tough and flexible and can be evaluated using ultrasonography. According to the questionnaire score, the model was highly satisfactory and has potential as a new educational tool.

Exploration of molecular machines in supramolecular soft robotic systems

Soft robotic system, a new era of material science, is rapidly developing with advanced processing technology in soft matters, featured with biomimetic nature. An important bottom-up approach is through the implementation of molecular machines into polymeric materials, however, the synchronized molecular motions, acumination of strain across multiple length-scales, and amplification into macroscopic actuations remained highly challenging. This review presents the significances, key design strategies, and outlook of the hierarchical supramolecular systems of molecular machines to develop novel types of supramolecular-based soft robotic systems.

Self- and Cross-Fusing of Furan-Based Polyurea Gels Dynamically Cross-Linked with Maleimides

Bio-based polyureas (PUs) with main-chain furan rings were synthesized by the polyaddition of 2,5-bis(aminomethyl)furan with various diisocyanates, such as methylene diphenyl diisocyanate. Several PU's were soluble in polar organic solvents, and were cast to form thermomechanically stable films with softening temperatures of over 100 °C. The furan rings of the PU main chains underwent a dynamic Diels-Alder (DA) reaction with bismaleimide (BMI) cross-linkers. While the mixed solution of PU and BMI did not show any apparent signs of reaction at room temperature, the DA reaction proceeded to form gels upon heating to 60 °C, which became a solution again by further heating to 80 °C (retro-DA reaction). The solution phase was maintained by rapid quenching from 80 °C to room temperature, while the gel was reformed upon slow cooling. The recovered gels exhibited self-healing properties. A scratch made by a hot knife at temperatures above 80 °C disappeared spontaneously. When two different gels were cut using a knife at room temperature, placed in contact with each other, and heated to 60 °C, they fused. The ability to control the DA/retro-DA reaction allowed gels of varying composition to heal.

Design of Cyclodextrin-Based Functional Systems for Biomedical Applications

Cyclodextrins (CDs) are a family of α-1,4-linked cyclic oligosaccharides that possess a hydrophobic cavity and a hydrophilic outer surface with abundant hydroxyl groups. This unique structural characteristic allows CDs to form inclusion complexes with various guest molecules and to functionalize with different substituents for the construction of novel sophisticated systems, ranging from derivatives to polymers, metal-organic frameworks, hydrogels, and other supramolecular assemblies. The excellent biocompatibility, selective recognition ability, and unique bioactive properties also make these CD-based functional systems especially attractive for biomedical applications. In this review, we highlight the characteristics and advantages of CDs as a starting point to design different functional materials and summarize the recent advances in the use of these materials for bioseparation, enzymatic catalysis, biochemical sensing, biomedical diagnosis and therapy.

Supramolecular self-assembly of the γ-cyclodextrin and perfluorononanoic acid system in aqueous solution

Recently, inclusion complexes formed from cyclodextrins (CDs) and surfactants have been found to play complex and important roles in supramolecular self-assembly. In this work, the self-assembly of perfluorononanoic acid (PFNA)/γ-cyclodextrin (γ-CD) in aqueous solution was investigated. The sole PFNA solution assembled into spherical uni-lamellar vesicles under certain concentrations as revealed by freeze-fracture transmission electron microscopy (FF-TEM) images. Interestingly, when γ-CD was added into the PFNA solution, one novel kind of cyclodextrin-based hydrogel with a crystal-like structure was obtained. The morphology of the hydrogels was inerratic parallel hexahedron or regular hexahedron as revealed by optical microscopy and scanning electron microscopy (SEM) measurements. Furthermore, the hydrogels were transformed into crystalline precipitates, which were composed of highly uniform tetragonal sheets with excellent crystallinity and homogeneous size distribution just by changing the γ-CD concentration. More amazingly, the crystal-like hydrogels were sensitive to shear and switched to solutions in their morphology with bar-like and rod-like aggregates and smaller square sheets under different shear rates, and the hydrogel-solution transition behavior was a reversable process. 1H NMR, Fourier transform infrared (FT-IR) and wide-angle X-ray diffraction (WXRD) measurements were performed to lead us to propose the formation mechanism of the above aggregates. Hopefully, our studies will cast new light on the fundamental investigations into the self-assembly of supramolecular systems of fluorinated surfactants and CD molecules and provide a new idea for smart material design.

Modification of Drug Crystallization by Cyclodextrins in Pre-formulation Study

Controlling drug crystallization is one of the important issues in pre-formulation study. In recent years, advanced approaches including the use of tailor-made additives have gathered considerable attention to control crystallization behavior of drugs. This review focuses on the use of hydrophilic cyclodextrins (CDs) as additives for controlling drug crystallization. CDs affect the crystallization of drugs in solution and in solid state based on a host-guest interaction. For example, 2,6-di-O-methyl-β-CD and 2-hydroxybutyl-β-CD suppressed solution-mediated transition of drugs during crystallization by the host-guest interaction; as a result, metastable forms selectively precipitated in solution. The use of CDs in crystal engineering provided an opportunity for the detection of a new polymorph by changing the crystallization pathway. It was also possible to modify crystal morphology (i.e., crystal habit) by selective suppression of crystal growth on a certain direction based on the host-gust interaction. For solid formulation, stable amorphous drug/CDs complex under humid conditions was prepared using two different CDs. An overview of some recent progress in the use of CDs in crystal engineering and in amorphous formulation is described in this review.

Complex systems that incorporate cyclodextrins to get materials for some specific applications

Cyclodextrins (CDs) are a family of biodegradable cyclic hydrocarbons composed of α-(1,4) linked glucopyranose subunits, the more common containing 6, 7 or 8 glucose units are named α, β and γ-cyclodextrins respectively. Since the discovery of CDs, they have attracted interest among scientists and the first studies were about the properties of the native compounds and in particular their use as catalysts of organic reactions. Characteristics features of different types of cyclodextrins stimulated investigation in different areas of research, due to its non-toxic and non-inmunogenic properties and also to the development of an improved industrial production. In this way, many materials with important properties have been developed. This mini-review will focus on chemical systems that use cyclodextrins, whatever linked covalently or mediated by the non covalent interactions, to build complex systems developed mainly during the last five years.

Macroscopic supramolecular assembly of rigid hydrogels assisted by a flexible spacing coating

To address the difficult challenge of realizing macroscopic supramolecular assembly (MSA) of high-modulus hydrogels, we propose a strategy of introducing a flexible spacing coating to improve the surface compliance for efficient MSA, which holds promise to develop versatile MSA methods for fabricating hydrogel-based tissue scaffolds, and to provide insight into the MSA mechanism.

Supramolecular Pharmaceutical Sciences: A Novel Concept Combining Pharmaceutical Sciences and Supramolecular Chemistry with a Focus on Cyclodextrin-Based Supermolecules

Supramolecular chemistry is an extremely useful and important domain for understanding pharmaceutical sciences because various physiological reactions and drug activities are based on supramolecular chemistry. However, it is not a major domain in the pharmaceutical field. In this review, we propose a new concept in pharmaceutical sciences termed "supramolecular pharmaceutical sciences," which combines pharmaceutical sciences and supramolecular chemistry. This concept could be useful for developing new ideas, methods, hypotheses, strategies, materials, and mechanisms in pharmaceutical sciences. Herein, we focus on cyclodextrin (CyD)-based supermolecules, because CyDs have been used not only as pharmaceutical excipients or active pharmaceutical ingredients but also as components of supermolecules.

Azo group(s) in selected macrocyclic compounds

Azobenzene derivatives due to their photo- and electroactive properties are an important group of compounds finding applications in diverse fields. Due to the possibility of controlling the trans-cis isomerization, azo-bearing structures are ideal building blocks for development of e.g. nanomaterials, smart polymers, molecular containers, photoswitches, and sensors. Important role play also macrocyclic compounds well known for their interesting binding properties. In this article selected macrocyclic compounds bearing azo group(s) are comprehensively described. Here, the relationship between compounds' structure and their properties (as e.g. ability to guest complexation, supramolecular structure formation, switching and motion) is reviewed.

Macroscopic supramolecular assembly to fabricate multiplexed DNA patterns for potential application in DNA chips

Macroscopic supramolecular assembly (MSA) is a newly established methodology to construct supramolecular materials directly from large building blocks. Demonstrations of MSA for various functions are urgently needed to advance MSA from fundamental studies to practical uses. Here we propose the fabrication of DNA microarrays by combining MSA and magnetic-assisted localization.

Self-Correction Strategy for Precise, Massive, and Parallel Macroscopic Supramolecular Assembly

Macroscopic supramolecular assembly (MSA) represents a new advancement in supramolecular chemistry involving building blocks with sizes beyond tens of micrometers associating through noncovalent interactions. MSA is established as a unique method to fabricate supramolecularly assembled materials by shortening the length scale between bulk materials and building blocks. However, improving the precise alignment during assembly to form orderly assembled structures remains a challenge. Although the pretreatment of building blocks can ameliorate order to a certain degree, defects or mismatching still exists, which limits the practical applications of MSA. Therefore, an iterative poststrategy is proposed, where self-correction based on dynamic assembly/disassembly is applied to achieve precise, massive, and parallel assembly. The self-correction process consists of two key steps: the identification of poorly ordered structures and the selective correction of these structures. This study develops a diffusion-kinetics-dependent disassembly to well identify the poorly aligned structures and correct these structures through iterations of disassembly/reassembly in a programmed fashion. Finally, a massive and parallel assembly of 100 precise dimers over eight iteration cycles is achieved, thus providing a powerful solution to the problem of processing insensitivity to errors in self-assembly-related methods.