Hydrogel nanotubes with ice helices entrapped within their internal conduits are a promising material for diabetic wound healing.

Nanomaterials (NMs) with unique structures and compositions can give rise to exotic physicochemical properties and applications. Despite the advancement in solution-based methods, scalable access to a wide range of crystal phases and intricate compositions is still challenging. Solid-state reaction (SSR) syntheses have high potential owing to their flexibility toward multielemental phases under feasibly high temperatures and solvent-free conditions as well as their scalability and simplicity. Controlling the nanoscale features through SSRs demands a strategic nanospace-confinement approach due to the risk of heat-induced reshaping and sintering. Here, we describe advanced SSR strategies for NM synthesis, focusing on mechanistic insights, novel nanoscale phenomena, and underlying principles using a series of examples under different categories. After introducing the history of classical SSRs, key theories, and definitions central to the topic, we categorize various modern SSR strategies based on the surrounding solid-state media used for nanostructure growth, conversion, and migration under nanospace or dimensional confinement. This comprehensive review will advance the quest for new materials design, synthesis, and applications.

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Graphene quantum dots (GQDs) are the harbingers of a paradigm shift that revitalize self-assembly of the colloidal puzzle by adding shape and size to the material-design palette. Although self-assembly is ubiquitous in nature, the extent to which these molecular legos can be engineered reminds us that we are still apprenticing polymer carpenters. In this quest to unlock exotic nanostructures ascending from eventual anisotropy, we have utilized different concentrations of GQDs as a filler in free-radical-mediated aqueous copolymerization. Extensive polymer grafting over the geometrically confined landscape of GQDs (0.05%) bolsters crystallization instilling a loom which steers interaction of polymeric cilia into interlaced equilateral triangles with high sophistication. Such two-dimensional (2D) assemblies epitomizing the planar tiling of “Star of David” forming a molecular kagome lattice (KL) without metal templation evoke petrichor. Interestingly, a higher percentage (0.3%) of GQDs allow selective tuning of the interfacial property of copolymers breaking symmetry due to surface energy incongruity, producing exotic Janus nanomicelles (JNMs). Herein, with the help of a suite of characterizations, we delineate the mechanism behind the formation of the KL and JNMs which forms a depot of heightened drug accretion with targeted delivery of 5-fluorouracil in the colon as validated by gamma scintigraphy studies.

Graphitic carbon nitride (gCN) has only recently experienced a renaissance in a myriad of domains despite existing as a long-established material described in the chemical literature. Notwithstanding the upturn, their conventional synthesis at extremely high temperatures yielding limiting compositions stands in the way of achieving a paradigm shift in gCN fabrication. With the ultimate goal of surpassing these hurdles, we utilize Ndoped carbon nanosheets (N-CNS) as a filler in free-radical-mediated aqueous copolymerization. By dispersing N-CNS in a polymer matrix, high-performance mechanically robust composites could be developed and tailored to individual applications. As-synthesized hydrogel nanocomposite systems are used to decode the balance for emulating evolutionary accomplishments of nature's nanocomposites like the "abalone's nacre". At a lower concentration (0.05%), N-CNS disperse homogeneously and interact intimately with the polymer matrix forming an "interphase" zone around individual nanofillers dramatically affecting the mobility of polymer chains to yield sheet architectures. On increasing the filler concentration (0.3%), the intercalation phenomenon gets perturbed due to an intrinsically oriented aggregation of nanofiller giving rise to a surge in entropy that leads to conspicuous buckling and tubular aggregates. At the interfacial regime, the poly(acrylic acid) domains come in closer proximity to the hydrophobic cages of N-CNS, and a nanoconfinement effect exerts high pressure manifesting acid-catalyzed condensation of melamine units to form, for the first time, quasi-two-dimensional heptazine-gCN (h-gCN) within hydrogel nanocomposites. Polymer properties are enhanced by the addition of N-CNS through complex interfacial interactions and the unique distributions of internanofiller distances. Endowed with mechanical properties that closely mimic natural skin and combined with the repurposed drug "losartan", these hydrogel nanocomposites offer scarless healing of second-degree burns.

An enchanting yet challenging task is the development of higher productivity in plants to meet the ample food demands for the growing global population while harmonizing the ecosystem using front-line technologies. This has kindled the practice of green microalgae cultivation as a driver of key biostimulant products, targeting agronomic needs. To this end, a prodigious and economical strategy for producing bioactive compounds (sources of secondary metabolites) from microalgae using carbon-based nanomaterials (CNMs) as a platform can circumvent these hurdles. Recently, the nanobionics approach of incorporating CNMs with living systems has emerged as a promising technique to develop organelles with new and augmented functions. Herein, we discuss the importance of 2D carbon nanosheets (CNS) as an alternative carbon source for the phototrophic cultivation of microalgae. CNS not only aids in cost reduction for algal cultivation but also confers combinatorial innate or exogenous functions that enhance its programmed biosynthetic metabolism, proliferation, or tolerance to stress. Moreover, the inherent ability of CNS to act as efficient biocatalysts can enhance the rate of photosynthesis. The primary focus of this mini-review is the development of an economic route for enhanced yield of bioactive compounds while simultaneously serving as a heterogeneous platform for enhancing the sustainable production of biostimulants including bioactive compounds from algal biomass for pharmaceutical and nutraceutical applications.

Nanoconfinement within flexible interfaces is a key step towards exploiting confinement effects in several biological and technological systems wherein flexible 2D materials are frequently utilized but are arduous to prepare. Hitherto unreported, the synthesis of 2D Hydrogel nanosheets (HNS) using a template- and catalyst-free process is developed representing a fertile ground for fundamental structure-property investigations. In due course of time, nucleating folds propagating along the edges trigger co-operative deformations of HNS generating regions of nanoconfinement within trapped water islands. These severely constricting surfaces force water molecules to pack within the nanoscale regime of HNS almost parallel to the surface bringing about phase transition into puckered rhombic ice with AA and AB Bernal stacking pattern, which was mostly restricted to Molecular dynamics (MD) studies so far. Interestingly, under high lateral pressure and spatial inhomogeneity within nanoscale confinement, bilayer rhombic ice structures were formed with an in-plane lattice spacing of 0.31 nm. In this work, a systematic exploration of rhombic ice formation within HNS has been delineated using High-resolution transmission electron microscopy (HRTEM), and its ultrathin morphology was examined using Atomic Force Microscopy (AFM). Scanning Electron Microscopy (SEM) images revealed high porosity while mechanical testing presented young’s modulus of 155 kPa with ~84% deformation, whereas contact angle suggested high hydrophilicity. The combinations of nanosheets, porosity, nanoconfinement, hydrophilicity, and mechanical strength, motivated us to explore their application as a scaffold for cartilage regeneration, by inducing chondrogenesis of human Wharton Jelly derived mesenchymal stem cells (hWJ MSCs). HNS promoted the formation of cell aggregates giving higher number of spheroid formation and a marked expression of chondrogenic markers (ColI, ColII, ColX, ACAN and S-100), thereby providing some cues for guiding chondrogenic differentiation.

Naturally occurring bioactive compounds have attracted significant interest from the perspective of scientific and industrial aspects owing to the wide range of technological, economic, and healthcare benefits. Their synthetic origin still suffers from several impeding challenges, such as expensive extraction and low yield. To address these critical issues, a unique hybridized system termed “algal-nanohybrids” was established by integrating green microalgae, Chlorella sorokiniana, with carbon-based heterostructured nanomaterials (CHNs), enhancing the microalgal growth for the sustainable augmentation of bioactive compounds as renewable sources of secondary metabolites. Hitherto, this work presents a new avenue in the formation of CHNs comprising propene-bridged cyanurate tetramer crystals nested on two-dimensional (2D) nanosheets, possessing excellent photocatalytic activity along with biocompatibility for the sustainable production of bioactive compounds. Mechanistic insights into the formation of CHNs and their plausible interaction with the algal cells were deciphered using a suite of characterization techniques. The conceptual significance of CHNs was elaborated, as an efficient nanomachinery for bolstering the enhanced production of lutein (97%) from C. sorokiniana, which is higher than that reported for other lutein-producing microalgae grown under photoautotrophic conditions. Interestingly, CHNs not only promoted microalgal biomass by 88% but also enhanced the production of chlorophyll a and carotenoids by 42 and 75%, respectively. This unprecedented work advances the synthesis of biocompatible CHNs, which can provide a breakthrough in the industry for the production of natural lutein and other bioactive compounds from microalgae.