Nanotechnology is a rapidly growing science of producing and utilizing nano-sized particles that measure in nanometers. These nanomaterials are already having an impact on health care. Now-a-days we are using nanoproducts in various fields. Of these, silver nanoparticles are playing a major role in the field of nanotechnology and nanomedicine.Their unique size-dependent properties make these materials superior and indispensable as they show unusual physical, chemical and biological properties. Silver nanoparticles have potential antimicrobial activity towards many pathogenic microbes. Along with this antimicrobial activity, silver nanoparticles are showing unacceptable toxic effects on human health and the environment. The chronic exposure to silver causes adverse effects such as permanent bluish-grey discoloration of the skin (argyria) and eyes (argyrosis). Besides argyria and argyrosis, exposure to soluble silver compounds may produce other toxic effects like liver and kidney damage, irritation of the eyes, skin, respiratory and intestinal tract and changes to blood cells. This review summarizes the hazardous effects of silver nanoparticles in the environment and theirs toxic effects on human health.
Nano-technology has entered the field of medicine in recent decades and many of the nanomaterials developed have already had a high impact on health care. Among nanomaterials, gold nanoparticles (GNPs) and gold quantum dots (QDs) are receiving significant attention because their unique physical, chemical and biological properties are quite different from the bulk of their counterparts. In this article, after a brief historical overview, the use of gold and nano-gold in medicine is reviewed, analyzed, and discussed. The review particularly deals with the use of GNPs and bio-conjugated GNPs in cancer treatment, drug or gene delivery, DNA detection, biomedical imaging including that of brain activity, enhancement of gene regulation, the detection of toxic metals, immuno-assays, disease detection and diagnostics, therapy and also the toxicity of gold and GNPs, etc. A number of novel applications of GNPs in medicine and perspectives of nano-gold use in medicine are also discussed.
Nanotechnology is an emerging field of science which is producing nano-sized materials. Some nanomaterials are having a significant impact in health care. Of these, carbon nanotubes (CNTs) represent one of the most promising materials in the field of nano-science and technology. Their potential in industrial applications has brought them much attention and the wide spectrum of usage has made it imperative that the impact of CNTs on human health and the environment is investigated thoroughly. In addition to their various beneficial applications, there is a potential for hazardous effects on human health. For example, the potential hazards through inhalation of CNTs have not been sufficiently evaluated. CNTs produce reactive oxygen species (ROS) which are associated with diminishing cellular activities, such as a decrease in the mitochondrial membrane potential etc. This paper reviews the hazardous influence of CNTs on human health and the environment. Specifically, the effects of CNTs on lung toxicity, skin irritation and CNTs cytotoxicity on various cell lines are reviewed. Biomedical applications and biocompatibility of carbon nanotubes are also summarized.
Gold phosphides show unique optical or semiconductor properties and there are extensive high technology applications, e.g. in laser diodes, etc. In spite of the various AuP structures known, the search for new materials is wide. Laser ablation synthesis is a promising screening and synthetic method. Generation of gold phosphides via laser ablation of red phosphorus and nanogold mixtures was studied using laser desorption ionisation time-of-flight mass spectrometry (LDI TOFMS). Gold clusters Au(m)(+) (m = 1 to ~35) were observed with a difference of one gold atom and their intensities were in decreasing order with respect to m. For P(n)(+) (n = 2 to ~111) clusters, the intensities of odd-numbered phosphorus clusters are much higher than those for even-numbered phosphorus clusters. During ablation of P-nanogold mixtures, clusters Au(m)(+) (m = 1-12), P(n)(+) (n = 2-7, 9, 11, 13-33, 35-95 (odd numbers)), AuP(n)(+) (n = 1, 2-88 (even numbers)), Au(2)P(n)(+) (n = 1-7, 14-16, 21-51 (odd numbers)), Au(3)P(n)(+) (n = 1-6, 8, 9, 14), Au(4)P(n)(+) (n = 1-9, 14-16), Au(5)P(n)(+) (n = 1-6, 14, 16), Au(6)P(n)(+) (n = 1-6), Au(7)P(n)(+) (n = 1-7), Au(8)P(n)(+) (n = 1-6, 8), Au(9)P(n)(+) (n = 1-10), Au(10)P(n)(+) (n = 1-8, 15), Au(11)P(n)(+) (n = 1-6), and Au(12)P(n)(+) (n = 1, 2, 4) were detected in positive ion mode. In negative ion mode, Au(m)(-) (m = 1-5), P(n)(-) (n = 2, 3, 5-11, 13-19, 21-35, 39, 41, 47, 49, 55 (odd numbers)), AuP(n)(-) (n = 4-6, 8-26, 30-36 (even numbers), 48), Au(2)P(n)(-) (n = 2-5, 8, 11, 13, 15, 17), A(3) P(n)(-) (n = 6-11, 32), Au(4)P(n)(-) (n = 1, 2, 4, 6, 10), Au(6)P(5)(-), and Au(7)P(8)(-) clusters were observed. In both modes, phosphorus-rich Au(m)P(n) clusters prevailed. The first experimental evidence for formation of AuP(60) and gold-covered phosphorus Au(12)P(n) (n = 1, 2, 4) clusters is given. The new gold phosphides generated might inspire synthesis of new Au-P materials with specific properties.
Detonation nanodiamonds (NDs) were studied by time-of-flight mass spectrometry (TOF MS). The formation of singly charged carbon clusters, C R n , with groups of clusters at n ¼ 1-35, n $160-400 and clusters with n $8000 was observed. On applying either high laser energy or ultrasound, the position and intensity of the maxima change and a new group of clusters at n $70-80 is formed. High carbon clusters consist of an even number of carbons while the percentage of odd-numbered clusters is quite low (£5-10%). On increasing the laser energy, the maximum of ionization (at n $200 carbons) is shifted towards the lower m/z values. It is suggested that this is mainly due to the disaggregation of the original NDs. However, the partial destruction of NDs is also possible. The carbon clusters (n $2-35) are partially hydrogenated and the average value of the hydrogenation was 10-30%. Trace impurities in NDs like Li, B, Fe, and others were detected at high laser energy. Several matrices for ionizing NDs were examined and NDs themselves can also be used as a matrix for the ionization of various organic compounds. When NDs were used as a matrix for gold nanoparticles, the formation of various gold carbides Au m C n was detected and their stoichiometry was determined. It was demonstrated that TOF MS can be used advantageously to analyze NDs, characterize their size distribution, aggregation, presence of trace impurities and surface chemistry.
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