Improved stability and selectivity of lytic peptides through self-assembly

The self-assembly of fine particles is a promising process for the production of nano-structures. In this process, aqueous suspension is often used. The spreading of the suspension on the substrate is a complex phenomenon that sometimes causes problems of instability. This paper discusses the instability phenomenon and proposes countermeasures from various aspects. It was found that special attention should be paid to the pattern design of site-selective assembly. Finally, complex structures made of particles of different sizes and materials are shown to demonstrate the improved stability after repeated dip-coating.

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Stable organic self-assembled microwire lasers for chemical vapor sensing

Communications Chemistry ◽

10.1038/s42004-021-00534-x ◽

2021 ◽

Vol 4 (1) ◽

Author(s):

Zheming Chen ◽

Chenghu Dai ◽

Wei Xiong ◽

Yanke Che ◽

Chuang Zhang

Keyword(s):

Self Assembly ◽

Sensor Arrays ◽

Optical Gain ◽

Chemical Vapor ◽

High Sensitivity ◽

Excitation Power ◽

Stimulated Emission ◽

Vapor Detection ◽

Vapor Sensing ◽

Improved Stability

AbstractOrganic microlasers hold great potentials in fabricating on-chip sensors for integrated photonic circuits due to their chemical versatility and reactivity. However, chemical vapor detection is still challenging for organic microlaser sensors, as it requires not only optical gain and self-assembly capability, but also rapid response to stimuli and long-term stability under high excitation power. In this work, a new laser dye 4,7-bis(9-octyl-7-(4-(octyloxy)phenyl)-9H-carbazol-2-yl)benzo[c][1,2,5]thiadiazole (BPCBT) is designed and synthesized, which self-assembles into microwires showing strong intramolecular charge transfer (ICT) photoluminescence with >80% quantum efficiency. It enables the lasing from BPCBT microwires under a low threshold of 16 μJ·mm−2·pulse−1 with significantly improved stability over conventional organic microlasers. The stimulated emission amplifies the fluorescence change in the BPCBT microwires under chemical vapors including various acid, acetone, and ethanol vapors, indicating high sensitivity and high selectivity of organic microlaser sensors desirable for compact sensor arrays in integrated photonics.

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In vitro and in vivo polysaccharides assembly: ultrastructural and cytochemical study of growing plant cell wall components.

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100083035 ◽

1978 ◽

Vol 36 (2) ◽

pp. 434-435

Author(s):

D. Reis ◽

B. Vian ◽

J. C. Roland

Keyword(s):

Cell Wall ◽

Self Assembly ◽

Plant Cell Wall ◽

Higher Plants ◽

Three Dimensional ◽

Cytochemical Study ◽

Wall Components

Wall morphogenesis in higher plants is a problem still open to controversy. Until now the possibility of a transmembrane control and the involvement of microtubules were mostly envisaged. Self-assembly processes have been observed in the case of walls of Chlamydomonas and bacteria. Spontaneous gelling interactions between xanthan and galactomannan from Ceratonia have been analyzed very recently. The present work provides indications that some processes of spontaneous aggregation could occur in higher plants during the formation and expansion of cell wall.Observations were performed on hypocotyl of mung bean (Phaseolus aureus) for which growth characteristics and wall composition have been previously defined.In situ, the walls of actively growing cells (primary walls) show an ordered three-dimensional organization (fig. 1). The wall is typically polylamellate with multifibrillar layers alternately transverse and longitudinal. Between these layers intermediate strata exist in which the orientation of microfibrils progressively rotates. Thus a progressive change in the morphogenetic activity occurs.

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The Nature of Rapidly Extracted Phycocyanin from the Blue-Green Alga Plectonema Boryanum

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100065870 ◽

1971 ◽

Vol 29 ◽

pp. 366-367

Author(s):

M. Kessel ◽

R. MacColl

Keyword(s):

Self Assembly ◽

Analytical Ultracentrifugation ◽

Uranyl Acetate ◽

The Self ◽

Major Protein ◽

Subunit Structure ◽

Blue Green Alga ◽

Thin Sections ◽

Blue Green Algae ◽

Cacodylate Buffer

The major protein of the blue-green algae is the biliprotein, C-phycocyanin (Amax = 620 nm), which is presumed to exist in the cell in the form of distinct aggregates called phycobilisomes. The self-assembly of C-phycocyanin from monomer to hexamer has been extensively studied, but the proposed next step in the assembly of a phycobilisome, the formation of 19s subunits, is completely unknown. We have used electron microscopy and analytical ultracentrifugation in combination with a method for rapid and gentle extraction of phycocyanin to study its subunit structure and assembly.To establish the existence of phycobilisomes, cells of P. boryanum in the log phase of growth, growing at a light intensity of 200 foot candles, were fixed in 2% glutaraldehyde in 0.1M cacodylate buffer, pH 7.0, for 3 hours at 4°C. The cells were post-fixed in 1% OsO4 in the same buffer overnight. Material was stained for 1 hour in uranyl acetate (1%), dehydrated and embedded in araldite and examined in thin sections.

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Video real-time imaging of artificial membranes during freeze-drying by cryo-electron microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010010216x ◽

1988 ◽

Vol 46 ◽

pp. 16-17

Author(s):

Alan S. Rudolph ◽

Ronald R. Price

Keyword(s):

Real Time ◽

Self Assembly ◽

Freeze Drying ◽

Video Capture ◽

Drying Process ◽

Artificial Membranes ◽

The Past ◽

Cryo Electron Microscopy ◽

Spherical Structures ◽

Capture Techniques

We have employed cryoelectron microscopy to visualize events that occur during the freeze-drying of artificial membranes by employing real time video capture techniques. Artificial membranes or liposomes which are spherical structures within internal aqueous space are stabilized by water which provides the driving force for spontaneous self-assembly of these structures. Previous assays of damage to these structures which are induced by freeze drying reveal that the two principal deleterious events that occur are 1) fusion of liposomes and 2) leakage of contents trapped within the liposome [1]. In the past the only way to access these events was to examine the liposomes following the dehydration event. This technique allows the event to be monitored in real time as the liposomes destabilize and as water is sublimed at cryo temperatures in the vacuum of the microscope. The method by which liposomes are compromised by freeze-drying are largely unknown. This technique has shown that cryo-protectants such as glycerol and carbohydrates are able to maintain liposomal structure throughout the drying process.

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Biomimetic materials: An introduction

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100129735 ◽

1992 ◽

Vol 50 (2) ◽

pp. 1020-1021 ◽

Cited By ~ 1

Author(s):

M. Sarikaya ◽

J. T. Staley ◽

I. A. Aksay

Keyword(s):

Self Assembly ◽

Structural Control ◽

Hierarchical Structures ◽

Ceramic Composites ◽

Advanced Materials ◽

Length Scale ◽

Spider Webs ◽

Biomimetic Materials ◽

Synthetic Materials ◽

All Ceramic

Biomimetics is an area of research in which the analysis of structures and functions of natural materials provide a source of inspiration for design and processing concepts for novel synthetic materials. Through biomimetics, it may be possible to establish structural control on a continuous length scale, resulting in superior structures able to withstand the requirements placed upon advanced materials. It is well recognized that biological systems efficiently produce complex and hierarchical structures on the molecular, micrometer, and macro scales with unique properties, and with greater structural control than is possible with synthetic materials. The dynamism of these systems allows the collection and transport of constituents; the nucleation, configuration, and growth of new structures by self-assembly; and the repair and replacement of old and damaged components. These materials include all-organic components such as spider webs and insect cuticles (Fig. 1); inorganic-organic composites, such as seashells (Fig. 2) and bones; all-ceramic composites, such as sea urchin teeth, spines, and other skeletal units (Fig. 3); and inorganic ultrafine magnetic and semiconducting particles produced by bacteria and algae, respectively (Fig. 4).

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