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This study investigated the colourful secondary particles formed by controlling the aggregation states of colloidal silica particles and the enhancement of the structural colouration of the secondary particles caused by adding black particles. We obtained glossy, partially structurally coloured secondary particles in the absence of NaCl, but matte, whitish secondary particles were obtained in the presence of NaCl. When a small amount of carbon black was incorporated into both types of secondary particles, the incoherent multiple scattering of light from the amorphous region was considerably reduced. However, the peak intensities in the reflection spectra, caused by Bragg reflection and by coherent single wavelength scattering, were only slightly decreased. Consequently, a brighter structural colour of these secondary particles was observed with the naked eye. Furthermore, when magnetite was added as a black particle, the coloured secondary particles could be moved and collected by applying an external magnetic field.

A periodically ordered interconnecting porous structure can be embodied in chemical gels by using closest-packed colloidal crystals as templates. The interconnecting porosity not only provides a quick response but also endows the porous gels with structural color arising from coherent Bragg optical diffraction. The structural colors revealed by porous gels can be regulated by several techniques, and thus, it is feasible to obtain desirable, smart, soft materials. A well-known thermosensitive monomer, N-isopropylacrylamide (NIPA), and other minor monomers were used to fabricate various structural colored gels. The selection of minor monomers depended on the targeted properties. This review focuses on the synthesis of templates, structural colored porous gels, and the applications of structural colored gel as smart soft materials for tunable photonic crystals.

This review will focus on the rapid, selective, accurate, easy, affordable, versatile, and point-of-care diagnosis of COVID-19 using electrochemical, optical, magnetic, aptameric, and plasmonic nano-biosensors.

The study aimed at inventorying of threatened plant species of Bangladesh to determine their status of occurrence for emphasizing the setting-up of national conservation strategies and sustainable management. Complete inventory of two families, the Apocynaceae and Vitaceae, has been made and recognized 28 threatened species facing environmental threats, and need sustainable conservation management. The study was based on long-term field investigation, survey of relevant floristic literature and examination of herbarium specimens. An enumeration of threatened taxa is prepared with updated field data on conservation status to include into Red Data Book of Bangladesh.

Hydrogel is advertently pertinent in numerous practical applications, but their breadth of use is often significantly restricted by their poor mechanical strength, including low toughness and reduced stretchability. A number of efforts to synthesize hydrogels with enhanced mechanical properties have already been rendered. However, a simple and widely adopted strategy for producing hydrogel with desirable strength and biocompatibility has yet to be materialized. Here, we have reported a hydrogel with incredible stretchability and toughness by strengthening the polyacrylamide (PAAm) network structure utilizing narrowly dispersed silica particles (SiO2) as a cross‐linker. SiO2 particles, grafted with vinyl end groups comprising 3‐(trimethoxysilyl)propyl methacrylate (MPTS), were used as a macro‐crosslinker (MSiO2) during the polymerization reaction of AAm to formulate hydrogel. The unique nature of synthesized hydrogel comprising both organic and inorganic compounds led to a rise in their wide‐spread applications as they have exceptional stretching and toughness of ∼59,400 Jm−2. Additionally, all synthesized hydrogels demonstrate high transparency in visible light wavelengths (above 75 %). The hydrogels exhibit significantly enhanced mechanical performance compared with the other ordinary type hydrogel prepared by conventional cross‐linker.

Like other conventional smart materials, structural color showing smart materials inherit physical and chemical characteristics imposed by the templates. Smart Material such as structural colored gel made of photonic crystal (PC) as template, exhibits angle dependent structural color because the color arises from the Bragg optical diffraction of light from crystal planes. But angle independent or low angle dependent structural color is required for devising of display with a wide viewing angle. To meet this purpose we prepared photonic glass (PG) from silica colloidal spheres. This PG is able to exhibit structural color, which is stable against the change of the angle of view and the angle of illumination. The transmittance spectrum evidences the angle independence of the structural color of PG. The Fast Fourier Transformation and the autocorrelation function prove that we prepared an amorphous material. The existence of short range order helps PG to exhibit angle independent structural color.

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