Micellar aggregates and hydrogels from phosphonobile salts

Advances in self-assembled injectable hydrogels for cancer therapy

Non-specific toxicity of chemotherapeutics and evolution of malignant tumors against them are major challenges for existing cancer chemotherapeutic regimens. Engineering of nanomaterials has attempted to minimize the toxicity of anticancer drugs, but systemic delivery of these nanomaterials still imposes many hurdles in their clinical use like burst release of chemotherapeutics and toxicity and immunogenicity associated with excipients of nanomaterials. However, there has been a surge in the development of natural and synthetic nanomaterials to deliver anticancer agents to the diseased (tumor) site as it can minimize the systemic circulation of anticancer drugs and reduce the toxicity-related challenges. Therefore, localized drug delivery is considered as the most effective way to deliver therapeutics but is further challenged by poor biodegradability, high immunogenicity, poor drug entrapment efficacy and inability to maintain sustained release of anticancer agents at the tumor site. This review maps out recent advancements in engineering of low molecular weight hydrogels derived from amino acid, fatty acyl, steroidal lipid and drug conjugated amphiphilic scaffolds. We have summarized the efforts for the development of molecular hydrogels in terms of biocompatibility, therapeutic potential and challenges associated with existing molecular hydrogels for cancer therapy.

A self-assembled CdSe QD-organogel hybrid: photophysical and thermoresponsive properties

A luminescent hybrid gel was prepared by incorporating organic ligand capped CdSe quantum dots (QDs) into a steroid-dimer derived organogel. Photophysical measurements and electron microscopy studies allowed us to understand the nature of the hybrid. Detailed analysis of the excited state dynamics of the hybrid was carried out using a kinetic decay model. The luminescence of the QDs in the hybrid was unaltered by taking it through a gel-sol-gel cycle induced by thermal stimuli. We believe that the results obtained herein provide a route to develop a thermoresponsive device for practical applications, because of the spatial assembly between soft organic scaffolds and colloidal QDs.

Spectroscopic imaging with spectral domain visible light optical coherence microscopy in Alzheimer's disease brain samples

A visible light spectral domain optical coherence microscopy system was developed. A high axial resolution of 0.88 μm in tissue was achieved using a broad visible light spectrum (425 - 685 nm). Healthy human brain tissue was imaged to quantify the difference between white (WM) and grey matter (GM) in intensity and attenuation. The high axial resolution enables the investigation of amyloid-beta plaques of various sizes in human brain tissue and animal models of Alzheimer's disease (AD). By performing a spectroscopic analysis of the OCM data, differences in the characteristics for WM, GM, and neuritic amyloid-beta plaques were found. To gain additional contrast, Congo red stained AD brain tissue was investigated. A first effort was made to investigate optically cleared mouse brain tissue to increase the penetration depth and visualize hyperscattering structures in deeper cortical regions.

Hierarchical self-assembly of photoluminescent CdS nanoparticles into a bile acid derived organogel: morphological and photophysical properties

A simple strategy for the preparation of a new bile acid derived organogel–CdS NP hybrid, and the study of its photophysical and morphological properties.

Supramolecular hydrogelation with bile acid derivatives: structures, properties and applications

Bile acid derivatives can form molecular hydrogels that may be useful for drug delivery, tissue engineering and nanotemplating.

Unlocking the potential of bile acids in synthesis, supramolecular/materials chemistry and nanoscience

The Maitra group has explored a variety of chemistry with bile acids during the past 15 years and these experiments have covered a wide variety of chemistry-asymmetric synthesis, molecular recognition, ion receptors/sensors, dendrimers, low molecular mass organo and hydrogelators, gel-nanoparticle composites, etc. Some of what excites us in this field is highlighted in this perspective article.

Simple esters of cholic acid as potent organogelators: direct imaging of the collapse of SAFINs

Unusual gelation of a number of organic solvents by allyl cholate and other simple esters of cholic acid is reported. These gels were characterized by SEM, AFM, polarizing optical microscopy (POM), X-ray powder diffraction and other techniques. Electron micrographs of the xerogels revealed the presence of highly entangled 3D fibrillar networks. Direct imaging of the collapse of SAFINs and their thermal stability were performed using variable temperature polarizing optical microscopy (POM).

Insight on the NMR study of supramolecular gels and its application to monitor molecular recognition on self-assembled fibers

The 1H NMR study of supramolecular gels formed by two organogelators derived from valine is described. The analysis of the variation of chemical shift values and relaxation times in the gel samples reveals that in these systems only discrete species are observed by 1H NMR. The reduced T2 values and negative NOEs that are measured upon gel formation can be ascribed to an exchange between discrete organogelator species and the gel network. This process is found to be fast in the time scale of 1H NMR relaxation and slow in the NMR observation frequency time scale. It is shown here that other molecules, aside from the gelator itself, can interact with the gel network and this process can be monitored easily by measurement of relaxation times. As a proof of principle, the selective interaction of 2,2'-bis(hydroxymethyl)biphenyl over diphenylmethane with the self-assembled fibers formed by one of the gelators in benzene is described.