Silicon Nanoparticles
With the rapid development of nanoscience and nanotechnology in multidisciplinary fields, nanomaterials have attracted extensive attention. Heavy-metal-free nanoscale silicon has been investigated in depth for its unparalleled physical and chemical properties such as the feasibility for surface functionalization, size-dependent tunable multicolor light emission, stability against photo bleaching and intriguingly, favorable nontoxicity. The applications of Si nanoparticles (NPs) to energy source, electronic, sensor, catalysis and biomedical purposes.
Silicon is a key material for microelectronics industry. In contrast to its extensive use in electronic device, bulk silicon has limited optoelectronic application due to indirect nature of its band gap. However, the up growth of nanotechnology has triggered many possible avenues for the applications of nanostructured silicon.
Silicon nanoparticles are promising for biological applications owing to their excellent biocompatibility, low toxicity, thermal stability, facile synthetic route, and large-scale synthetic availability. The particle size, crystallinity, porosity, and shape can be precisely manipulated, enabling the silica nanoparticles for various applications. Moreover, numerous available surface modifications of silica nanoparticles permit their control of surface chemistry to achieve drug loading, good dispensability, and site-specific targeting. These properties, if combined and developed appropriately, make silica nanoparticles a platform for biomedical imaging, detecting, therapeutic delivery, monitoring, and ablative therapies. With the design of diverse dopants, surface functional groups, and assembly techniques, multifunctional nanoparticles can be developed with theranostic applications. Silica nanoparticles have also widely applied in other areas such as energy source, electronic, sensor, and catalysis purposes.
Furthermore, Silicon quantum dots (QDs), i.e. nanoparticles (NPs) with aspherical shape, are considered as a robust nanocomponentfor diverse applications. However, the most useful QDs indiverse applications are nowadays based on highly toxiccompounds like CdSe, CdTe etc. Silicon QDs are characterized by fluorescence similar to that of traditional QDs, but their toxicity is reduced. The biocompatibility, high photoluminescence quantum efficiency, stability to photo bleaching, and the non-blinking behavior of silicon QDs’, aswell as the size-tuneable emission and the possibility offunctionalization, are the properties that have made siliconQDs highly efficient for biological applications.
It has alsobeen observed that silicon QDs are efficient photo sensitizers of singlet oxygen and they have been used for in vivo drug delivery, labs-on-chips applications and for bioanalysis. Ithas been shown that the efficiency under two-photon excitation is three times higher than that of fluorescein. This characteristic is important for their use in bioimaging. The growing interest in silicon-based nanomaterials and theirapplications resulted in an increase in the number of studieson their adverse biological effects.
The properties of silicon (Si) are generally understood based onatomic and bulk Si models.1 Because of the benign, abundantand inexpensive nature of Si materials; the expansion of Si usagesin electronic, optoelectric, biological and other diverse applications is highly desirable. Due to their diverse properties (e.g.size-dependent emission and band gap, biocompatibility, andhigh-sensitivity and reactive Si–H surface) and the huge Simicroelectronics market, Si nanostructures are graduallybecoming one of the most important classes of nano-semiconductors in the sensor, electronic, optic, and catalysis fields.
Si is an indirect band gap semiconductor with a low probability for phonon-assisted, radiative electron–hole recombination(i.e. resulting in the spontaneous emission of photons). Nevertheless, there is global research interest in developing a Si lightemitting diode, ultimately Si-based lasers, and in looking at thephotoluminescence (PL) properties of nanoscale Si particles.
Silicon is a key material for microelectronics industry. In contrast to its extensive use in electronic device, bulk silicon has limited optoelectronic application due to indirect nature of its band gap. However, the up growth of nanotechnology has triggered many possible avenues for the applications of nanostructured silicon.
Silicon nanoparticles are promising for biological applications owing to their excellent biocompatibility, low toxicity, thermal stability, facile synthetic route, and large-scale synthetic availability. The particle size, crystallinity, porosity, and shape can be precisely manipulated, enabling the silica nanoparticles for various applications. Moreover, numerous available surface modifications of silica nanoparticles permit their control of surface chemistry to achieve drug loading, good dispensability, and site-specific targeting. These properties, if combined and developed appropriately, make silica nanoparticles a platform for biomedical imaging, detecting, therapeutic delivery, monitoring, and ablative therapies. With the design of diverse dopants, surface functional groups, and assembly techniques, multifunctional nanoparticles can be developed with theranostic applications. Silica nanoparticles have also widely applied in other areas such as energy source, electronic, sensor, and catalysis purposes.
Furthermore, Silicon quantum dots (QDs), i.e. nanoparticles (NPs) with aspherical shape, are considered as a robust nanocomponentfor diverse applications. However, the most useful QDs indiverse applications are nowadays based on highly toxiccompounds like CdSe, CdTe etc. Silicon QDs are characterized by fluorescence similar to that of traditional QDs, but their toxicity is reduced. The biocompatibility, high photoluminescence quantum efficiency, stability to photo bleaching, and the non-blinking behavior of silicon QDs’, aswell as the size-tuneable emission and the possibility offunctionalization, are the properties that have made siliconQDs highly efficient for biological applications.
It has alsobeen observed that silicon QDs are efficient photo sensitizers of singlet oxygen and they have been used for in vivo drug delivery, labs-on-chips applications and for bioanalysis. Ithas been shown that the efficiency under two-photon excitation is three times higher than that of fluorescein. This characteristic is important for their use in bioimaging. The growing interest in silicon-based nanomaterials and theirapplications resulted in an increase in the number of studieson their adverse biological effects.
The properties of silicon (Si) are generally understood based onatomic and bulk Si models.1 Because of the benign, abundantand inexpensive nature of Si materials; the expansion of Si usagesin electronic, optoelectric, biological and other diverse applications is highly desirable. Due to their diverse properties (e.g.size-dependent emission and band gap, biocompatibility, andhigh-sensitivity and reactive Si–H surface) and the huge Simicroelectronics market, Si nanostructures are graduallybecoming one of the most important classes of nano-semiconductors in the sensor, electronic, optic, and catalysis fields.
Si is an indirect band gap semiconductor with a low probability for phonon-assisted, radiative electron–hole recombination(i.e. resulting in the spontaneous emission of photons). Nevertheless, there is global research interest in developing a Si lightemitting diode, ultimately Si-based lasers, and in looking at thephotoluminescence (PL) properties of nanoscale Si particles.
Silicon nanoparticles in agriculture
Silicon has also been observed to be used by plants to strengthen their cell walls; the plants of the Equisetaceae family cannot survive in nutrient solutions lacking silicon. Therefore, silicon is considered an essential element for the Equisetaceae family. Silicon content in plants was observed to vary from 0.1 to 10%, which was attributed to different mechanisms of silicon uptake. Dissolved silicon was reported to be absorbed by plants in the form of monosilicic acid, and in some plants with a high accumulation capacity of metalloids, different silicon transporter genes (such as LSi1, LSi2, and LSi6) have been reported to help in its transportation. Nanoparticles may exhibit different properties than their bulk material due to their small size, greater surface area-to-weight ratio, and different shapes. Similarly, silicon nanoparticles (Si-NPs) were observed to exhibit different physical and chemical properties than their bulk material. Therefore, it is important to know how differently Silicon-NPs interact within the environment. Due to their unique properties, Si-NPs exhibit great potential in agriculture and may work better in alleviating different abiotic stresses than bulk material. Apart from the direct impact of Si-NPs on plant growth and development, Si-NPs can also be used as nanopesticides, nano-herbicides, and nanofertilizers. Silicon nanoparticles may also be used as delivery agents for proteins, nucleotides, and other chemicals in plants; nano-zeolite and nanosensors incorporate Si-NPs and may be effectively used in agriculture for increasing the water retention of soil and for soil monitoring, respectively.
Energy and Electronics
Si NPs exhibit fascinating electronic and optical properties compared with bulk silicon and have been investigated in depth for photovoltaic applications. For lithium ion battery applications, silicon formulations such as silicon nanowires, silicon nanotubes and micro porous silicon nanoparticles have been widely investigated to overcome the disappointing shortcomings of previous silicon anodes. Despite the change in nanostructure, researchers have ceaselessly been searching for novel candidate anode materials featuring higher Li-ion storage and stronger rechargeable capability to serve as substitutes for low charge-stored carbon based anodes.