DNA-surfactant complexes: self-assembly properties and applications

Facile Mechanophore Integration in Heterogeneous Biologically Derived Materials via "Dip-Conjugation"

Mechanical forces play critical roles in a wide variety of biological processes and diseases, yet measuring them directly at the molecular level remains one of the main challenges of mechanobiology. Here, we show a strategy to "Dip-conjugate" biologically derived materials at the chemical level to mechanophores, force-responsive molecular entities, using Click-chemistry. Contrary to classical prepolymerization mechanophore incorporation, this new protocol leads to detectable mechanochromic response with as low as 5% strain, finally making mechanophores relevant for many biological processes that have previously been inaccessible. Our results demonstrate the ubiquity of the technique with activation in synthetic polymers, carbohydrates, and proteins under mechanical force, with alpaca wool fibers as a key example. These results push the limits for mechanophore use in far more types of polymeric materials in applications ranging from molecular-level force damage detection to direct and quantitative 3D force measurements in mechanobiology.

Supramolecular DNA-based catalysis in organic solvents

The distinct folding accompanied by its polymorphic character renders DNA G-quadruplexes promising biomolecular building blocks to construct novel DNA-based and supramolecular assemblies. However, the highly polar nature of DNA limits the use of G-quadruplexes to water as a solvent. In addition, the archetypical G-quadruplex fold needs to be stabilized by metal-cations, which is usually a potassium ion. Here, we show that a noncovalent PEGylation process enabled by electrostatic interactions allows the first metal-free G-quadruplexes in organic solvents. Strikingly, incorporation of an iron-containing porphyrin renders the self-assembled metal-free G-quadruplex catalytically active in organic solvents. Hence, these "supraG4zymes" enable DNA-based catalysis in organic media. The results will allow the broad utilization of DNA G-quadruplexes in nonaqueous environments.

Oligonucleotide based nanogels for cancer therapeutics

Oligonucleotide-based nanogels, as nascent biomaterials, possess several unique functional, structural, and physicochemical features with excellent drug-loading capacity and high potential for cancer gene therapy. Ongoing studies utilizing oligonucleotide-based nanogels hold great promise, as these cutting-edge nanoplatforms can be elegantly developed with predesigned oligonucleotide sequences and complementary strands which are self-assembled or chemically crosslinked leading to the development of nanogels with predictable shape and tunable size with the desired functional properties. Current paper provides a summary of the properties, preparation methods, and applications of oligonucleotide-based nanogels in cancer therapy. The review is focused on both conventional and modified forms of oligonucleotide-based nanogels, including targeted nanogels, smart release nanogels (responsive to stimuli such as pH, temperature, and enzymes), as well as nanogels used for gene delivery. Their application in cancer immunotherapy and vaccination, photodynamic therapy, and diagnostic applications when combined with other nanoparticles is further discussed. Despite emerging designs in the development of oligonucleotide based nanogels, this field of study is still in its infancy, and clinical translation of these versatile nano-vehicles might face challenges. Hence, extensive research must be performed on in vivo behavior of such platforms determining their biodistribution, biological fate, and acute/subacute toxicity.

Assembly and optically triggered disassembly of lipid-DNA origami fibers

The co-assembly of lipids and other compounds has recently gained increasing interest. Here, we report the formation of stimuli-responsive lipid-DNA origami fibers through the electrostatic co-assembly of cationic lipids and 6-helix bundle (6HB) DNA origami. The photosensitive lipid degrades when exposed to UV-A light, which allows a photoinduced, controlled release of the 6HBs from the fibers. The presented complexation strategy may find uses in developing responsive nanomaterials e.g. for therapeutics.

Biomimetic Mineralization: From Microscopic to Macroscopic Materials and Their Biomedical Applications

Biomineralization is an attractive pathway to produce mineral-based biomaterials with high performance and hierarchical structures. To date, the biomineralization process and mechanism have been extensively studied, especially for the formation of bone, teeth, and nacre. Inspired by those, abundant biomimetic mineralized materials have been fabricated for biomedical applications. Those bioinspired materials generally exhibit great mechanical properties and biological functions. Nevertheless, substantial gaps remain between biomimetic materials and natural materials, particularly with respect to mechanical properties and mutiscale structures. This Review summarizes the recent progress of micro- and macroscopic biomimetic mineralization from the perspective of materials synthesis and biomedical applications. To begin with, we discuss the progress of biomimetic mineralization at the microscopic level. The mechanical strength, stability, and functionality of the nano- and micromaterials are significantly improved by introducing biominerals, such as DNA nanostructures, nanovaccines, and living cells. Next, numerous biomimetic strategies based on biomineralization at the macroscopic scale are highlighted, including in situ mineralization and bottom-up assembly of mineralized building blocks. Finally, challenges and future perspectives regarding the development of biomimetic mineralization are also presented with the aim of offering insights for the rational design and fabrication of next-generation biomimetic mineralized materials.

Role of Gemini Surfactants with Variable Spacers and SiO2 Nanoparticles in ct-DNA Compaction and Applications toward In Vitro/In Vivo Gene Delivery

Compaction of calf thymus DNA (ct-DNA) by two cationic gemini surfactants, 12-4-12 and 12-8-12, in the absence and presence of negatively charged SiO₂ nanoparticles (NPs) (∼100 nm) has been explored using various techniques. 12-8-12 having a longer hydrophobic spacer induces a greater extent of ct-DNA compaction than 12-4-12, which becomes more efficient with SiO₂ NPs. While 50% ct-DNA compaction in the presence of SiO₂ NPs occurs at ∼77 nM of 12-8-12 and ∼130 nM of 12-4-12, but a conventional counterpart surfactant, DTAB, does it at its concentration as high as ∼7 μM. Time-resolved fluorescence anisotropy measurements show changes in the rotational dynamics of a fluorescent probe, DAPI, and helix segments in the condensed DNA. Fluorescence lifetime data and ethidium bromide exclusion assays reveal the binding sites of surfactants to ct-DNA. 12-8-12 with SiO₂ NPs has shown the highest cell viability (≥90%) and least cell death in the human embryonic kidney (HEK) 293 cell lines in contrast to the cell viability of ≤80% for DTAB. These results show that 12-8-12 with SiO₂ NPs has the highest time and dose-dependent cytotoxicity compared to 12-8-12 and 12-4-12 in the murine breast cancer 4T1 cell line. Fluorescence microscopy and flow cytometry are performed for in vitro cellular uptake of YOYO-1-labeled ct-DNA with surfactants and SiO₂ NPs using 4T1 cells after 3 and 6 h incubations. The in vivo tumor accumulation studies are carried out using a real-time in vivo imaging system after intravenous injection of the samples into 4T1 tumor-bearing mice. 12-8-12 with SiO₂ has delivered the highest amount of ct-DNA in cells and tumors in a time-dependent manner. Thus, the application of a gemini surfactant with a hydrophobic spacer and SiO₂ NPs in compacting and delivering ct-DNA to the tumor is proven, warranting its further exploration in nucleic acid therapy for cancer treatment.

Water-resistant free-standing DNA-complexed films with antioxidant and H2O2-responsive activity

Water-insoluble DNA complexes are suitable for producing free-standing DNA films due to their low water sensitivity, which prevents their rapid degradation in aqueous environments. Here, we proposed two types of free-standing films that exhibit low dissolution rates in water: low molecular weight chitosan (LCS)-DNA films and phosphatidylcholine (PC)-cetyltrimethylammonium (CTMA)-DNA films. The structure and binding characteristics of the LCS-DNA and PC-CTMA-DNA complexes were investigated with UV-Vis spectroscopy and via the fluorescent characteristics of daunorubicin bound to them. A simple drop-casting method was then adopted for both complexes to fabricate free-standing films. An increase in antioxidant activity and water-resistance of the LCS-DNA DNA film was observed when the molar ratio of LCS to DNA was increased, but the dissolution rate of the LCS-DNA film was also dependent on the ionic strength of the dissolving solution. Fourteen days were required to dissolve the LCS-DNA film in deionized water, whereas immediate dissolution was observed in 1× phosphate-buffered saline (PBS). Deformation of the PC-CTMA-DNA film was accelerated by H₂O₂, such that the PC-CTMA-DNA film was degraded after 21 days of immersion in 1× PBS with H₂O₂. Due to the low dissolution rate in water and antioxidant activity, the free-standing LCS-DNA film should be able to store and protect embedded clinical materials, such as proteins and intercalating drugs, from moisture and enable localized delivery of treatments to designated sites. Also, the free-standing PC-CTMA-DNA film could be a biocompatible candidate for use as a membrane or sensor for detecting the levels of reactive oxygen species.

Engineering DNA-Guided Hydroxyapatite Bulk Materials with High Stiffness and Outstanding Antimicrobial Ability for Dental Inlay Applications

Programmable base pair interactions at the nanoscale make DNA an attractive scaffold for forming hydroxyapatite (HAP) nanostructures. However, engineering macroscale HAP mineralization guided by DNA molecules remains challenging. To overcome this issue, a facile strategy is developed for the fabrication of ultrastiff DNA-HAP bulk composites. The electrostatic complexation of DNA and a surfactant with a quaternary ammonium salt group enables the formation of long-range ordered scaffolds using electrospinning. The growth of 1D and 2D HAP minerals is thus realized by this DNA template at a macroscale. Remarkably, the as-prepared DNA-HAP composites exhibit an ultrahigh Young's modulus of ≈25 GPa, which is comparable to natural HAP and superior to most artificial mineralized composites. Furthermore, a new type of dental inlay with outstanding antibacterial properties is developed using the stiff DNA-HAP. The encapsulated quaternary ammonium group within the dense HAP endows the composite with long-lasting and local antibacterial activity. Therefore, this new type of super-stiff biomaterial holds great potential for oral prosthetic applications.

Kinetics and Mechanism of In Situ Metallization of Bulk DNA Films

DNA-templated metallization is broadly investigated in the fabrication of metallic structures by virtue of the unique DNA-metal ion interaction. However, current DNA-templated synthesis is primarily carried out based on pure DNA in an aqueous solution. In this study, we present in situ synthesis of metallic structures in a natural DNA complex bulk film by UV light irradiation, where the growth of silver particles is resolved by in situ time-resolved small-angle X-ray scattering and dielectric spectroscopy. Our studies provide physical insights into the kinetics and mechanisms of natural DNA metallization, in correlation with the multi-stage switching operations in the bulk phase, paving the way towards the development of versatile biomaterial composites with tunable physical properties for optical storage, plasmonics, and catalytic applications.

Exploring the binding mode of ester-based cationic gemini surfactants with calf thymus DNA: A detailed physicochemical, spectroscopic and theoretical study

Gene therapy is a transfectant method for the treatment of hereditary disease, which transfers the gene mutation into the cells. In the view of the high prospects of utilization of cationic gemini surfactants as a non-viral vector for the gene transfection, we have made a comprehensive study on the interactions between a recently synthesized series of ester-functionalized cationic C_m-E2O-C_m gemini surfactants (m = 12, 14 and 16) with calf thymus deoxyribonucleic acid (ctDNA) utilizing various techniques. The micellization behavior of gemini surfactants has been altered in the presence of ctDNA. A series of measurements (fluorescence, UV-vis and time-resolved fluorescence) show that the quenching of ctDNA proceeds by a static mechanism. The competitive displacement studies (EB, AO and HO), KI quenching analysis, CD studies and viscosity measurements suggested intercalative binding mode in a stoichiometry ratio of 1:1 with the K_b (binding constant) order being: C₁₆-E2O-C₁₆ > C₁₄-E2O-C₁₄ > C₁₂-E2O-C₁₂. The thermodynamic parameters show that the geminis interacted with ctDNA spontaneously through ionic/electrostatic interactions. Furthermore, the theoretical approaches offer accurate insights about the binding of gemini surfactants with DNA, and are in consistence with the experimental results.

Sequence Does Not Matter: The Biomedical Applications of DNA-Based Coatings and Cores

Biomedical applications of DNA are diverse but are usually associated with specific recognition of target nucleotide sequences or proteins and with gene delivery for therapeutic or biotechnological purposes. However, other aspects of DNA functionalities, like its nontoxicity, biodegradability, polyelectrolyte nature, stability, thermo-responsivity and charge transfer ability that are rather independent of its sequence, have recently become highly appreciated in material science and biomedicine. Whereas the latest achievements in structural DNA nanotechnology associated with DNA sequence recognition and Watson–Crick base pairing between complementary nucleotides are regularly reviewed, the recent uses of DNA as a raw material in biomedicine have not been summarized. This review paper describes the main biomedical applications of DNA that do not involve any synthesis or extraction of oligo- or polynucleotides with specified sequences. These sequence-independent applications currently include some types of drug delivery systems, biocompatible coatings, fire retardant and antimicrobial coatings and biosensors. The reinforcement of DNA properties by DNA complexation with nanoparticles is also described as a field of further research.

MWNTs or PEG as Stability Enhancers for DNA-Cationic Surfactant Gel Particles

Cationic surfactants interact with DNA (Deoxyribonucleic acid), forming surfactant-DNA complexes that offer particularly efficient control for encapsulation and release of DNA from DNA gel particles. In the present work, DNA-based particles were prepared using CTAB (Cetyltrimethylammonium bromide) as the cationic surfactant and modified using two different additives: (Multi-Walled Carbon Nanotubes) MWNT or PEG (Poly Ethylene Glycol). The use of both additives to form composites increased the stability of the gel particles. The stability was monitored by the release of DNA and CTAB in different pH solutions. However, not much is known about the influence of pH on DNA–surfactant interaction and the release of DNA and surfactant from gel particles. It was observed that the solubilization of DNA occurs only in very acid media, while that of CTAB does not depend on pH and gets to a plateau after about 8 h. Within 2 h in contact with a pH = 2 solution, about 1% DNA and CTAB was released. Complete destruction for the gel particles was observed in pH = 2 solution after 17 days for PEG and 20 days for MWNT. The composite particles show a considerably enlarged sustained release span compared to the unmodified ones. The dehydration-rehydration studies show that the structure of the composite gel particles, as determined from SAXS (Small-Angle-X-Ray-Scattering) experiments, is similar to that of the unmodified ones. These studies will allow a better knowledge of these particles’ formation and evolution in view of possible applications in drug delivery and release.

Modulation of cell membrane functionalization with aggregates of oligodeoxynucleotides containing alkyl chain-modified uridines

In this study, we prepared oligodeoxynucleotides (ODNs) containing the uridine base modified by an alkyl chain at the 5-position (AU) and characterized their aggregate formation, localization, and functions in cells. These experiments revealed that aggregates of these ODNs were readily transported into cells, but their localization was dependent upon the number of hydrophobic units. ODNs with one modified AU were transported in the cytosol, while ODNs with multiple AU modifications resulted in their accumulation at the cell membrane. We also examined the ability of the AU-modified ODNs to capture small molecules at the cell membrane and their cellular uptake. We positioned a thioflavin-T (ThT)-binding aptamer on the cell membrane by means of hybridization with ODNs with three AUs at the strand end. Treatment with ThT resulted in its efficient uptake into cells, due to the capture of the ThT by the aptamers on the cell membrane. Thus, we demonstrated the functionalization of cell membranes with modified ODNs and the efficient delivery of small molecules into the cells.

Harnessing the physicochemical properties of DNA as a multifunctional biomaterial for biomedical and other applications

The biological purpose of DNA is to store, replicate, and convey genetic information in cells. Progress in molecular genetics have led to its widespread applications in gene editing, gene therapy, and forensic science. However, in addition to its role as a genetic material, DNA has also emerged as a nongenetic, generic material for diverse biomedical applications. DNA is essentially a natural biopolymer that can be precisely programed by simple chemical modifications to construct materials with desired mechanical, biological, and structural properties. This review critically deciphers the chemical tools and strategies that are currently being employed to harness the nongenetic functions of DNA. Here, the primary product of interest has been crosslinked, hydrated polymers, or hydrogels. State-of-the-art applications of macroscopic, DNA-based hydrogels in the fields of environment, electrochemistry, biologics delivery, and regenerative therapy have been extensively reviewed. Additionally, the review encompasses the status of DNA as a clinically and commercially viable material and provides insight into future possibilities.

Spatiotemporally programmable cascade hybridization of hairpin DNA in polymeric nanoframework for precise siRNA delivery

DNA nanostructures have been demonstrated as promising carriers for gene delivery. In the carrier design, spatiotemporally programmable assembly of DNA under nanoconfinement is important but has proven highly challenging due to the complexity-scalability-error of DNA. Herein, a DNA nanotechnology-based strategy via the cascade hybridization chain reaction (HCR) of DNA hairpins in polymeric nanoframework has been developed to achieve spatiotemporally programmable assembly of DNA under nanoconfinement for precise siRNA delivery. The nanoframework is prepared via precipitation polymerization with Acrydite-DNA as cross-linker. The potential energy stored in the loops of DNA hairpins can overcome the steric effect in the nanoframework, which can help initiate cascade HCR of DNA hairpins and achieve efficient siRNA loading. The designer tethering sequence between DNA and RNA guarantees a triphosadenine triggered siRNA release specifically in cellular cytoplasm. Nanoframework provides stability and ease of functionalization, which helps address the complexity-scalability-error of DNA. It is exemplified that the phenylboronate installation on nanoframework enhanced cellular uptake and smoothed the lysosomal escape. Cellular results show that the siRNA loaded nanoframework down-regulated the levels of relevant mRNA and protein. In vivo experiments show significant therapeutic efficacy of using siPLK1 loaded nanoframework to suppress tumor growth.

Assembly and functionalization of supramolecular polymers from DNA-conjugated squaraine oligomers

DNA conjugated oligomers of organic molecules are candidates for applications in the materials and medical sciences, in diagnostics, in optical devices, for delivery or for the design of complex molecular architectures. Herein, we describe the synthesis and properties of DNA-conjugated squaraine (Sq) oligomers. The oligomers self-assemble into supramolecular polymers that are amenable to further functionalization via DNA hybridization, as shown by the attachment of gold nanoparticles (AuNPs).

The assembly of supramolecular polymers of DNA-linked squaraine oligomers and their subsequent derivatization is described.

DNA-Origami-Templated Growth of Multilamellar Lipid Assemblies

Lipids are important building blocks in cellular compartments, and therefore their self-assembly into well-defined hierarchical structures has gained increasing interest. Cationic lipids and unstructured DNA can co-assemble into highly ordered structures (lipoplexes), but potential applications of lipoplexes are still limited. Using scaffolded DNA origami nanostructures could aid in resolving these drawbacks. Here, we have complexed DNA origami together with a cationic lipid 1,2-dioleoly-3-trimethylammonium-propane (DOTAP) and studied their self-assembly driven by electrostatic and hydrophobic interactions. The results suggest that the DNA origami function as templates for the growth of multilamellar lipid structures and that the DNA origami are embedded in the formed lipid matrix. Furthermore, the lipid encapsulation was found to significantly shield the DNA origami against nuclease digestion. The presented complexation strategy is suitable for a wide range of DNA-based templates and could therefore find uses in construction of cell-membrane-associated components.

Chiroptical property enhancement of chiral Eu(III) complex upon association with DNA-CTMA

DNA-based materials have attracted much attention due to their unique photo-functional properties and potential applications in various fields such as luminescent and biological systems, nanodevices, etc. In this study, the photophysical properties of a chiral Eu(III) complex, namely (Eu(D-facam)₃), within DNA films were extensively investigated. The enhancement of photoluminescence (more than 25-folds increase of luminescence quantum yield) and degree of circularly polarization in luminescence (g_lum = − 0.6) was observed upon interaction with DNA. Various photophysical analyses suggested that the emission enhancement was mainly due to an increase of the sensitization efficiency (high η_sens) from the ligands to Eu(III) and suppression of the vibrational deactivation upon immobilization onto the DNA molecule. From CD and VCD measurements, it was suggested that the coordination structure of Eu(D-facam)₃ was affected by the interaction with DNA, suggesting that the structural change of Eu(D-facam)₃ contributed to the improvement of its luminescent properties.

Dodecyltrimethylammonium bromide surfactant effects on DNA: Unraveling the competition between electrostatic and hydrophobic interactions

We present a new study on the interaction of the DNA molecule with the surfactant dodecyltrimethylammonium bromide (DTAB), performed mainly with optical tweezers. Single-molecule force spectroscopy experiments performed in the low-force entropic regime allowed a robust characterization of the DNA-DTAB interaction, unveiling how the surfactant changes the mechanical properties of the biopolymer, the binding parameters, and the competition of the two mechanisms involved in the interaction: electrostatic attraction between the cationic surfactant heads and the negative phosphate backbone of the DNA and hydrophobic interactions between the tails of the bound DTAB molecules, which can result in DNA compaction in solution depending on the quantity of bound surfactant. Finally, force clamp experiments with magnetic tweezers and gel electrophoresis assays confirm that DTAB compacts DNA depending not only on the surfactant concentration but also on the conformation of the biopolymer in solution. The present study provides new insights on general aspects of the DNA-surfactant complexes formation, contributing to the fundamental knowledge of the physics of such interactions.

Designed Boron-Rich Polymeric Nanoparticles Based on Nano-ion Pairing for Boron Delivery

Boron-rich particles with the boron fraction ca.10-20 wt % of controllable shape and size that can be easily prepared via simple ion co-assembly are promising material for tumor treatment by boron neutron capture therapy. Electroneutral, dynamic core-shell polymeric nanoparticles were prepared by co-assembly of cationic PEO-block-PGEA diblock copolymer with sodium closo-dodecaborate, Na₂ [B₁₂ H₁₂ ]. This is the first example of polymer nanoparticles based on [B₁₂ H₁₂ ]^2- nano-ion pairing. The high [B₁₂ H₁₂ ]^2- loading is proven by calorimetry at physiological salt concentration. As a result of rational design, rod-, worm- and sphere-like particles were produced and further tested using human glioblastoma and cervical carcinoma cell lines. Rod-like particles yielded the highest internalization capability in all tested cell lines.

Injectable and NIR-Responsive DNA-Inorganic Hybrid Hydrogels with Outstanding Photothermal Therapy

Surgical excision is one of the main treatments for malignant tumors. However, high risk of tumour recurrence is a major challenge. Near-infrared (NIR)-light-induced tumor photothermal therapy has been studied, while its clinical applications are still restricted due to the limited therapeutic effects. To address this, here, a novel NIR-light-responsive and injectable DNA-mediated upconversion and Au nanoparticle hybrid (DNA-UCNP-Au) hydrogel is developed. Due to the confined and concentrated environment induced by the interaction between adjacent DNA strands and UCNP-Au NPs, an ultrastrong photothermal effect is observed. A photothermal efficiency as high as 42.7% is realized in the hydrogel, which is superior to pristine inorganic particles. Upon direct peritumoral injection of the hydrogel and with the treatment of 808 nm laser irradiation, tumors are eradicated and no recurrence is observed. Meanwhile, there are no side effects on normal tissues due to the local treatment. Taking advantage of the high phototherapeutic effect, biocompatibility, and flexible operability in this system, a novel approach for malignant tumor therapy is demonstrated.

Lipid-oligonucleotide conjugates for bioapplications

Lipid-oligonucleotide conjugates (LONs) are powerful molecular-engineering materials for various applications ranging from biosensors to biomedicine. Their unique amphiphilic structures enable the self-assembly and the conveyance of information with high fidelity. In particular, LONs present remarkable potential in measuring cellular mechanical forces and monitoring cell behaviors. LONs are also essential sensing tools for intracellular imaging and have been employed in developing cell-surface-anchored DNA nanostructures for biomimetic-engineering studies. When incorporating therapeutic oligonucleotides or small-molecule drugs, LONs hold promise for targeted therapy. Moreover, LONs mediate the controllable assembly and fusion of vesicles based on DNA-strand displacements, contributing to nanoreactor construction and macromolecule delivery. In this review, we will summarize the general synthesis strategies of LONs, provide some characterization analysis and emphasize recent advances in bioanalytical and biomedical applications. We will also consider the relevant challenges and suggest future directions for building better functional LONs in nanotechnology and materials-science applications.

The plant dehydrin Lti30 stabilizes lipid lamellar structures in varying hydration conditions

A major challenge to plant growth and survival are changes in temperature and diminishing water supply. During acute temperature and water stress, plants often express stress proteins, such as dehydrins, which are intrinsically disordered hydrophilic proteins. In this article, we investigated how the dehydrin Lti30 from Arabidopsis thaliana stabilizes membrane systems that are exposed to large changes in hydration. We also compared the effects of Lti30 on membranes with those of the simple osmolytes urea and trimethylamine N-oxide. Using X-ray diffraction and solid-state NMR, we studied lipid-protein self-assembly at varying hydration levels. We made the following observations: 1) the association of Lti30 with anionic membranes relies on electrostatic attraction, and the protein is located in the bilayer interfacial membrane region; 2) Lti30 can stabilize the lamellar multilayer structure, making it insensitive to variations in water content; 3) in lipid systems with a composition similar to those present in some seeds and plants, dehydrin can prevent the formation of nonlamellar phases upon drying, which may be crucial for maintaining membrane integrity; and 4) Lti30 stabilizes bilayer structures both at high and low water contents, whereas the small osmolyte molecules mainly prevent dehydration-induced transitions. These results corroborate the idea that dehydrins are part of a sensitive and multifaceted regulatory mechanism that protects plant cells against stress.

DNA thermotropic liquid crystals controlled by positively charged catanionic bilayer vesicles

We report DNA thermotropic liquid crystal (TLC) formation by positively charged catanionic surfactant bilayer vesicles. The properties of DNA TLCs were found to be manipulated by both the chemical structures of cationic and anionic surfactants and the DNA amount. Positively charged catanionic bilayer vesicles bond to negative DNA sites resulting in the transition from vesicles to long range ordered lamellar crystals of DNA-catanionic surfactants, as confirmed by cryo- and freeze-fracture (FF) TEM observations and small-angle X-ray scattering (SAXS) measurements.

Reconfigurable Liquids Stabilized by DNA Surfactants

Polyelectrolyte microcapsules can be produced either by the layer-by-layer assembly technique or the formation of polyelectrolyte complexes at the liquid-liquid interface. Here, we describe the design and construction of DNA microcapsules using the cooperative assembly of DNA and amine-functionalized polyhedral oligomeric silsesquioxane (POSS-NH₂) at the oil-water interface. "Janus-like" DNA surfactants (DNASs) assemble in situ at the interface, forming an elastic film. By controlling the jamming and unjamming behavior of DNASs, the interfacial assemblies can assume three different physical states: solid-like, elastomer-like, and liquid-like, similar to that seen with thermoplastics upon heating, that change from a glassy to a rubbery state, and then to a viscous liquid. By the interfacial jamming of DNASs, the liquid structures can be locked-in and reconfigured, showing promising potentials for drug delivery, biphasic reactors, and programmable liquid constructs.

A DNA and Self-Doped Conjugated Polyelectrolyte Assembled for Organic Optoelectronics and Bioelectronics

Deoxyribonucleic acid (DNA) and a self-doped conjugated polyelectrolyte, poly(4-(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl-methoxy)-1-butanesulfonic acid (PEDOT-S), are assembled for organic optoelectronics and bioelectronics. The DNA's helix-coil phase transition in water is studied as a function of composition by thermo-optical analysis. DNA and PEDOT-S are functionalized by using a surfactant, cetyltrimethylammonium chloride (CTMA), and DNA:CTMA, PEDOT-S:CTMA, and DNA:CTMA:PEDOT-S:CTMA complexes were characterized regarding thermal, optical, morphological, and structural properties. Finally, DNA and DNA:PEDOT-S mixtures are processed in water for fabricating organized films through brushing. The electrical properties of these films are characterized using an interdigitated electrode. The films show an electronic conductivity of ∼10^-6-10^-5 S/cm in a range of semiconductors.

Visualization of materials using the confocal laser scanning microscopy technique

The development of materials science always benefits from advanced characterizations. Currently, imaging techniques are of great technological importance in both fundamental and applied research on materials. In comparison to conventional visualization methods, confocal laser scanning microscopy (CLSM) is non-invasive, with macroscale and high-contrast scanning, a simple and fast sample preparation procedure as well as easy operation. In addition, CLSM allows rapid acquisition of longitudinal and cross-sectional images at any position in a material. Therefore, the CLSM-based visualization technique could provide direct and model-independent insight into material characterizations. This review summarizes the recent applications of CLSM in materials science. The current CLSM approaches for the visualization of surface structures, internal structures, spatial structures and reaction processes are discussed in detail. Finally, we provide our thoughts and predictions on the future development of CLSM in materials science. The purpose of this review is to guide researchers to build a suitable CLSM approach for material characterizations, and to open viable opportunities and inspirations for the development of new strategies aiming at the preparation of advanced materials. We hope that this review will be useful for a wide range of research communities of materials science, chemistry, and engineering.

Influence factors on the critical micelle concentration determination using pyrene as a probe and a simple method of preparing samples

The critical micelle concentration (CMC) is an important parameter of widely used surfactants and needs to be measured in the application and development of surfactants. Fluorometric method is a widely used method determining CMC values owing to the advantages of highly sensitivity, fast response and wide application range. There are two common methods (I and II) of preparing samples for CMC fluorometric determination. In the process of developing CMC probes with aggregation-induced emission (AIE) characteristics, we found that methods I and II were not suitable for CMC probes with AIE charateristics and developed a new sample preparation method (III), which is not only suitable for CMC probes with AIE characteristic but also decreases operation procedures and errors owing to omitting the addition of micro amount of dyes into each sample. To ascertain if method III is also suitable for other CMC probes without AIE characteristics, the CMC values of surfactants were determined by fluorometric method using widely used pyrene without AIE charateristic as probe and methods I-III to prepare samples. The obtained experimental results proved that method III not only was suitable for preparation of samples for CMC determination of surfactants using pyrene as probe but also led to the least average deviation (methods I-III led to ±0.13, ±0.34 and ±0.05 mM deviation for the CMC determination of sodium dodecyl sulfate (SDS), respectively). The CMC determination using pyrene as probe is based on its change in the ratio (I FIII/I FI) of its emission peaks I and III with surfactant concentration. Unexpectedly, it was found that the I FIII/I FI value of pyrene in surfactant solutions is sensitive to the measurement conditions changing exciting light energy, such as slit widths and sample-measured number. In addition, it was found that surfactant SDS or cetrimonium bromide from different suppliers not only has significantly different CMC values but also leads to very different I FIII/I FI values of pyrene in a certain concentration of surfactant, which can be used as a simple method to distinguish the same surfactant with different CMC values.

Determining the Critical Micelle Concentration of Surfactants by a Simple and Fast Titration Method

Critical micelle concentration (CMC) is a crucial parameter of widely used surfactants, and many methods have been developed for CMC determination. However, the current methods for CMC determination, such as conductive, surface tension, and fluorometric methods, are tedious and time- and sample-consuming because a series of samples with different concentrations of surfactants need to be prepared and measured. Although an economical, simple, and fast titration method for CMC determination (only one sample and several minutes are needed) was reported using changes in the color/fluorescence of ionic organic dyes, it has not been used in practical CMC determination owing to the disadvantages of these dyes: very narrow application range (only suitable for cationic or anionic surfactants) and difficult to identify titration end point, especially using different concentrations (10-300 μM) for the same kind surfactants. Here a C6-unsubstituted tetrahydropyrimidine (THP-T1) was found to possess unique and excellent characteristics in titrated surfactant solutions: above CMC, preferring to dissolve in micelles and showing no emission, and not until near/at CMC, being released from micelles and instantly forming aggregates with strong fluorescence. The fluorescence-turn-on change at CMC (titration end point) is so sensitive that it can be clearly observed without comparison of blank and control of dye concentration, and the concentration (c'_THP) of THP-T1 in titrated solution at CMC is only about 1 μM for zwitterionic surfactants and 2.5 μM for other kinds of surfactants. The CMC values determined by the THP-T1-based titration method are almost the same as those determined by the fluorometric method using THP-T1 as probe. THP-T1 overcomes the disadvantages of reported dyes for CMC titration and realizes the economical, simple and fast CMC titration of different kinds of surfactants for the first time.

Synthesis, structure-activity relationship and biological evaluation of tetracationic gemini Dabco-surfactants for transdermal liposomal formulations

In this study, we report the relationship between structure, self-assembly behavior and antimicrobial activity of multicationic gemini surfactants and their successful use as stabilizers of a new liposomal formulation for transdermal drug delivery. New surfactants containing natural moiety 1,4-diazabicyclo[2.2.2]octane with four charges and two hydrophobic chains (n-Dabco-s-Dabco-n, where s = 2, 6, 12 and n = 12, 14, 16, 18) were synthesized. A linear dependence of the CMC decrease, with the increase of the number of carbon atoms in alkyl groups (slope 0.23) was shown. The aggregation numbers of n-Dabco-2-Dabco-n are smaller than 30 and they decrease with increasing alkyl chain length. This is in compliance with the larger surface area per n-Dabco-2-Dabco-n molecule. New liposomal formulations loading Rhodamine B phosphatidylcholine (with mean size about 100 nm and increased zeta potential from -7 ± 2 mV to +55 ± 2 mV) have been successfully stabilized by n-Dabco-s-Dabco-n surfactants. These formulations were designed to improve the bioavailability and skin permeation of loaded compound. The antibacterial activity of Dabco-surfactants was shown to be strongly affected by their structure (alkyl chain length and number of charged nitrogen). 12-Dabco-2-Dabco-12 was the most active (MIC = 0.48, 0.98 and 15.6 µg/mL against S. aureus, B. cereus and E. coli, respectively) without hemolytic activity at 3.1 µg/mL concentration. PC/14-Dabco-2-Dabco-14-liposomes were shown to be the best formulation, with the highest antibacterial activity against Sa (MIC = 7.8 μg‧mL^-1) and lowest cytotoxicity (IC₅₀ > 125). The modification of liposomes by Dabco-surfactants stabilizes the membrane of the vesicles, preventing the release of rhodamine B and impairing the penetration of the dye across Strat-M® membrane. Cellular uptake of rhodamine B-loaded PC/12-Dabco-2-Dabco-12-liposomes was also reported. This is the first example of cationic mixed liposomes containing Dabco-surfactants of potential interest for transdermal drug delivery.

Nano-Inspired Technologies for Peptide Delivery

Nano-inspired technologies offer unique opportunities to treat numerous diseases by using therapeutic peptides. Therapeutic peptides have attractive pharmacological profiles and can be manufactured at relatively low costs. The major advantages of using a nanodelivery approach comprises significantly lower required dosages compared to systemic delivery, and thus reduced toxicity and immunogenicity. The combination of therapeutic peptides with delivery peptides and nanoparticles or small molecule drugs offers systemic treatment approaches, instead of aiming for single biological targets or pathways. This review article discusses exemplary state-of-the-art nanosized delivery systems for therapeutic peptides and antibodies, as well as their biochemical and biophysical foundations and emphasizes still remaining challenges. The competition between using different nanoplatforms, such as liposome-, hydrogel-, polymer-, silica nanosphere-, or nanosponge-based delivery systems is still "on" and no clear frontrunner has emerged to date.

Multivalent Ultrasensitive Interfacing of Supramolecular 1D Nanoplatforms

Multivalent display on linear platforms is used by many biomolecular systems to effectively interact with their corresponding binding partners in a dose-responsive and ultrasensitive manner appropriate to the biological system at hand. Synthetic supramolecular multivalent displays offer a matching approach for the modular and bottom-up construction and systematic study of dynamic 1D materials. Fundamental studies into multivalent interactions between such linear, 1D materials have been lacking because of the absence of appropriate modular nanoplatforms. In this work we interfaced two synthetic multivalent linear nanoplatforms based on a dynamic supramolecular polymer, formed by hybrid discotic-oligonucleotide monomers, and a series of complementary DNA-duplex-based multivalent ligands, also with appended short oligonucleotides. The combination of these two multivalent nanoplatforms provides for the first time entry to study multivalent effects in dynamic 1D systems, of relevance for the conceptual understanding of multivalency in biology and for the generation of novel multivalent biomaterials. Together the two nanoscaffolds provide easy access to libraries of multivalent ligands with tunable affinities. The DNA scaffold allows for exact control over valency and spatial ligand distribution, and the discotic supramolecular polymer allows for dynamic adaptation and control over receptor density. The interaction between the two nanoplatforms was studied as a function of ligand interaction strength, valency, and density. Usage of the enhancement parameter β allowed quantification of the effects of ligand valency and affinity. The results reveal a generalized principle of additive binding increments. Receptor density is shown to be crucially and nonlinearly correlated to complex formation, leading to ultrasensitive responses. The results reveal that, not unlike biomolecular signaling, high density multivalent display of receptors is crucial for functionally increased affinities.

Photoregulation between small DNAs and reversible photochromic molecules

Oligonucleotides are widely used biological materials in the fields of biomedicine, nanotechnology, and materials science. Due to the demands for the photoregulation of DNA activities, scientists are placing more and more research interest in the interactions between reversible photochromic molecules and DNAs. Photochromic molecules can work as switches for regulating the DNAs' behavior under light irradiation; meanwhile, DNAs also exert influence over the photochromic molecules. The photochromic molecules can be attached to DNAs either by covalent bonds or by noncovalent forces, which results in different regulative functions. Azobenzenes, spiropyrans, diarylethenes, and stilbene-like compounds are important photochromic molecules working as photoswitches. By summarizing their interactions with oligonucleotides, this review intends to facilitate the relevant research on oligonucleotides/photochromic molecules in the biological and medicinal fields and in materials science.

Alkyl triphenylphosphonium surfactants as nucleic acid carriers: complexation efficacy toward DNA decamers, interaction with lipid bilayers and cytotoxicity studies

Herein, for the first time the complexation ability of a homological series of triphenylphosphonium surfactants (TPPB-n) toward DNA decamers has been explored. Formation of lipoplexes was confirmed by alternative techniques, including dynamic light scattering, indicating the occurrence of nanosized complexes (ca. 100-150 nm), and monitoring the charge neutralization of nucleotide phosphate groups and the fluorescence quenching of dye-intercalator ethidium bromide. The complexation efficacy of TPPB-surfactants toward an oligonucleotide (ONu) is compared with that of reference cationic surfactants. Strong effects of the alkyl chain length and the structure of the head group on the surfactant/ONu interaction are revealed, which probably occur via different mechanisms, with electrostatic and hydrophobic forces or intercalation imbedding involved. Phosphonium surfactants are shown to be capable of disordering lipid bilayers, which is supported by a decrease in the temperature of the main phase transition, T_m. This effect enhances with an increase in the alkyl chain length, indicating the integration of TPPB-n with lipid membranes. This markedly differs from the behavior of typical cationic surfactant cetyltrimethylammonium bromide, which induces an increase in the T_m value. It was demonstrated that the cytotoxicity of TPPB-n in terms of the MTT-test on a human cell line 293T nonmonotonically changes within the homological series, with the highest cytotoxicity exhibited by the dodecyl and tetradecyl homologs.

Chiral self-assembly of fullerene clusters on CT-DNA templates

Herein we discuss the differential interaction of three monosubstituted fullerene derivatives possessing pyridinium, aniline or phenothiazine end groups (F-Py, F-An and F-PTz, respectively) with calf thymus DNA (CT-DNA), probed via spectroscopic and imaging techniques. The pyridinium derivative, F-Py becomes molecularly dissolved in 10% DMSO-PBS and interacts with CT-DNA via groove binding and electrostatic interactions, leading to the initial condensation of CT-DNA into micrometer sized aggregates and subsequent precipitation. On the other hand, the aniline derivative F-An, which is reported to form nanoclusters of 3-5 nm size, interacts with DNA through ordered, chiral assemblies on the CT-DNA template, thus perturbing the highly networked structure of CT-DNA to form nanonetworks, which eventually transform into condensed aggregates. The binding interactions between CT-DNA and F-An nanoclusters were established via UV-Vis, AFM and TEM analysis, and the chiral nature of the fullerene nanocluster assemblies on CT-DNA was confirmed by the presence of induced circular dichroism that was exhibited around the 250-370 nm region, corresponding to F-An nanocluster absorption. In contrast, the phenothiazine derivative F-PTz, which forms larger nanoclusters of ∼70 nm size in 10% DMSO-PBS, exhibited only weak interactions with CT-DNA without affecting its network structure. These results demonstrate the role of the hydrophobic-hydrophilic balance in the design of DNA interacting fullerene derivatives by controlling their cluster size and interactions with CT-DNA, and are significant in applications such as DNA condensation, gene delivery and dimension controlled nanomaterial fabrication.

DNA-Functionalized Supramolecular Polymers: Dynamic Multicomponent Assemblies with Emergent Properties

Recent years have witnessed an increasing interest in hybrid molecular systems in which the programmability of DNA hybridization is used to introduce enhanced molecular control in synthetic systems. The first examples of DNA-functionalized supramolecular polymers have been reported only recently, but have already revealed structural and functional properties that are not easily obtained in either synthetic supramolecular polymers or DNA-only based systems. In this Topical Review, we provide an overview of the various forms of additional control offered by DNA hybridization for different types of supramolecular polymers and discuss how orthogonal supramolecular interactions in these hybrid systems can give rise to emergent structural and functional properties.

Preparation of membrane-mimicking lamellar structures by molecular confinement of hybrid nanocomposites

Hybrid nanocomposites are multiphase systems with a wide range of applications. Some nanocomposites are water insoluble thereby preventing several applications. Thus, we prepared telechelic PEO with glucose molecules to form water-soluble lamellar nanostructures by co-assembly with metallacarborane. The lamellas formed by PEO/metallacarborane decorated by glucose molecules on the surface can serve as delivery agents for boron clusters and benzoxaboroles.