Mesostructured Silica Supports for Functional Materials and Molecular Machines

Angelos, Sarah; Johansson, Erik; Stoddart, J. Fraser; Zink, Jeffrey I.

doi:10.1002/adfm.200601217

Cited by 188 publications

(154 citation statements)

References 67 publications

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“…Furthermore, carefully designed compounds can incorporate recognition stations that can be turned "on" or "off" by a variety of means, permitting direct control over molecular-scale movements within MIMs. These unique molecular machines based on MIMs working in concert have been incorporated into drug-delivery vehicles, [60][61][62][63][64][65][66] electrochromic systems, 19,[67][68][69][70] and molecular electronic devices. 26,55,[71][72][73][74][75][76][77][78] Switchable rotaxanes are particularly well-suited for use as artificial muscles because of the potential to harness the collective efforts of ensembles of linear molecules to exert linear forces, as opposed to catenanes, which exhibit radial motions.…”

Section: Rotaxane-based Redox-driven Molecular Machinesmentioning

confidence: 99%

Molecular, Supramolecular, and Macromolecular Motors and Artificial Muscles

Li¹,

Paxton²,

Baughman³

et al. 2009

MRS Bull.

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Recent developments in chemical synthesis, nanoscale assembly, and molecularscale measurements enable the extension of the concept of macroscopic machines to the molecular and supramolecular levels. Molecular machines are capable of performing mechanical movements in response to external stimuli. They offer the potential to couple electrical or other forms of energy to mechanical action at the nano-and molecular scales. Working hierarchically and in concert, they can form actuators referred to as artificial muscles, in analogy to biological systems. We describe the principles behind driven motion and assembly at the molecular scale and recent advances in the field of molecular-level electromechanical machines, molecular motors, and artificial muscles. We discuss the challenges and successes in making these assemblies work cooperatively to function at larger scales.

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Section: Rotaxane-based Redox-driven Molecular Machinesmentioning

confidence: 99%

Molecular, Supramolecular, and Macromolecular Motors and Artificial Muscles

Li¹,

Paxton²,

Baughman³

et al. 2009

MRS Bull.

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“…[1][2][3][4] Further developments in the synthesis and modification of nanosized mesoporous silica materials have created new possibilities for biomedical applications. [5][6][7][8] As opposed to nonporous silica nanoparticles, both the surface and the pore interior of mesostructured nanoparticles can be modified with functional groups, such that they become compatible in various solutions and are able to store different types of molecules.…”

mentioning

confidence: 99%

Antimicrobial Activity of Silver Nanocrystals Encapsulated in Mesoporous Silica Nanoparticles

2009

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MCM-41 type mesoporous silicate particles have attracted a significant amount of research interest due to the ordered porous structure of the materials, their facile synthetic methods, and their broad range of applications. [1][2][3][4] Further developments in the synthesis and modification of nanosized mesoporous silica materials have created new possibilities for biomedical applications. [5][6][7][8] As opposed to nonporous silica nanoparticles, both the surface and the pore interior of mesostructured nanoparticles can be modified with functional groups, such that they become compatible in various solutions and are able to store different types of molecules. [9][10][11][12][13][14][15] These nanomaterials have been well demonstrated for their biocompatibility, [16,17] and in their utilization as fluorescent markers for cells, [18] gene-transfection agents, [19] and delivery vehicles for proteins and anticancer drugs. [20,21] Studies of the interaction of mesoporous silicate nanoparticles with bacteria are rare. The nanoparticles were modified with dye molecules to enable studies of possible interaction using fluorescence microscopy. Rhodamine B isothiocyanate (RITC) was reacted with aminopropyltriethoxysilane and mixed with the silica precursor tetraethylorthosilicate (TEOS) to functionalize the interior pores and surface of the particles with the dye molecules without disrupting the mesostructure. [6,21,22] For our previous studies, two types of bacteria were used: Bacillus anthracis BH450 (B. anthracis), as the Gram-positive model, and Escherichia coli BL21 DE3 (E. coli), as the Gram-negative model. Upon mixing the nanoparticles with bacteria, red fluorescence of the nanoparticles was found to overlap with B. anthracis, but not with E. coli, suggesting that the particle adherence to the bacteria may depend on the bacterial strain and surface characteristic of the nanoparticles (Fig. S1, Supporting Information). Encouraged by these initial results and the report on use of nitric oxidereleasing silica nanoparticles as bactericidal agents, [23] we continued the studies in order to develop mesostructured silica nanocomposites that can store large amounts of antimicrobial materials and slowly release the bactericidal agents over an extended time period.The ability to encapsulate inorganic materials by growing mesostructured silica around them introduces additional functionality to the nanoparticles. Gold, semiconductor, and iron oxide nanocrystals can be incorporated within mesoporous silica nanoparticles to create a yolk/shell architecture without collapsing the mesostructure. [24][25][26][27] In comparison to the traditional coating of inorganic nanocrystals with nonporous silica or polymer, [28][29][30][31][32] the mesoporous silica shell offers the advantage of being able to store molecules or to slowly release the encapsulated inorganic materials. [33,34] Based on the works by Trewyn et al. in synthesizing mesoporous nanoparticles that release bactericidal cationic surfactants, [35] and Jiang et al. in prepar...

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“…Subsequently, the macrocyclic component threaded on the interlocked molecule's backbone by noncovalent interactions could serve as the gate that controls access of guest molecules into and out of the nanopores of the mesoporous silica nanoparticles, to act as nanovalves [5,6]. One of the attractive features of nanovalve systems is the ability to induce controlled release (a diffusion-controlled system) of guest molecules from the nanopores using various external stimuli such as pH change [7] addition of salts, [8] redox process, [9] and light [10].…”

Section: Highlightmentioning

confidence: 99%

The Quest of Smart Nanomaterials for Multiple Drug Delivery

Leung¹

2017

Arch Chem Res

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HighlightRecently, the research of smart nanomaterials embedded with molecular and nano-machines has gained much attention on accounting for their prolific applications in the fields of nanotechnology, in particular for controlled drug delivery and bio-mimetics. For biomolecules and various biological systems, the functions of the sensor, processor and effector are associated with the hierarchical structures based on covalent or noncovalent bonds. Combining these functions in synthetic nanomaterials could lead to a mimic of the natural feedback systems. The realization of the proposed research idea would hopefully shed light on mimicking functional enzyme systems [1][2][3][4].For example, "smart" switchable interlocking molecules could be attached to the pore orifices of mesoporous silica nanoparticles. Subsequently, the macrocyclic component threaded on the interlocked molecule's backbone by noncovalent interactions could serve as the gate that controls access of guest molecules into and out of the nanopores of the mesoporous silica nanoparticles, to act as nanovalves [5,6]. One of the attractive features of nanovalve systems is the ability to induce controlled release (a diffusion-controlled system) of guest molecules from the nanopores using various external stimuli such as pH change [7] addition of salts, [8] redox process, [9] and light [10]. Moreover, these ON/OFF switchable molecular nanovalves process superior properties of reversibility and reusability of the materials as well as the regional and temporal control of substrate release. To facilitate practical biomedical applications in vivo, the use of non-invasive low-intensity ultrasound [11] has been routinely employed for pregnancy diagnosis, as a stimulus to trigger drug release from the drugencapsulated smart materials. On the other hand, the ability to carry hydrophobic and hydrophilic drugs to specific cancer site (targeting) is beneficial to cancer treatment with smart materials [12]. In particular, smart materials that are responsive to significant pH change between cancerous cells (pH~5) and normal cells (pH~7), are candidates for targeted therapy. Recently, relatively non-cytotoxic iron oxide magnetic nanocomposites with tunable particle and pore sizes and their hollow and core/shell derivatives were introduced to successfully demonstrate a better magnetic separation method for recycling the nanomaterials from the reaction mixture using a magnet [13][14][15][16][17][18][19][20]. Different magnetic hybrid nanostructures have been successfully fabricated in spheres, wires, etc, which would be capable to covalently attach or physically encapsulate supramolecules, organic molecules, and drugs [21][22][23][24][25][26]. For covalent attachment of molecules, the process can be performed by chemical coupling reactions between molecules with functional groups and nanoparticles with reactive surface at their periphery or at the mesopores. For physical encapsulation of molecules to the nanoparticles, porous nanoparticles with tunable pore size can be em...

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Mesostructured Silica Supports for Functional Materials and Molecular Machines

Cited by 188 publications

References 67 publications

Molecular, Supramolecular, and Macromolecular Motors and Artificial Muscles

Molecular, Supramolecular, and Macromolecular Motors and Artificial Muscles

Antimicrobial Activity of Silver Nanocrystals Encapsulated in Mesoporous Silica Nanoparticles

The Quest of Smart Nanomaterials for Multiple Drug Delivery

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