Priscyla D. Marcato

Mechanistic aspects of biosynthesis of silver nanoparticles by several Fusarium oxysporum strains

Extracellular production of metal nanoparticles by several strains of the fungus Fusarium oxysporum was carried out. It was found that aqueous silver ions when exposed to several Fusarium oxysporum strains are reduced in solution, thereby leading to the formation of silver hydrosol. The silver nanoparticles were in the range of 20–50 nm in dimensions. The reduction of the metal ions occurs by a nitrate-dependent reductase and a shuttle quinone extracellular process. The potentialities of this nanotechnological design based in fugal biosynthesis of nanoparticles for several technical applications are important, including their high potential as antibacterial material.

Mechanistic aspects in the biogenic synthesis of extracellular metal nanoparticles by peptides, bacteria, fungi, and plants

Metal nanoparticles have been studied and applied in many areas including the biomedical, agricultural, electronic fields, etc. Several products of colloidal silver are already on the market. Research on new, eco-friendly and cheaper methods has been initiated. Biological production of metal nanoparticles has been studied by many researchers due to the convenience of the method that produces small particles stabilized by protein. However, the mechanism involved in this production has not yet been elucidated although hypothetical mechanisms have been proposed in the literature. Thus, this review discusses the various mechanisms provided for the biological synthesis of metal nanoparticles by peptides, bacteria, fungi, and plants. One thing that is clear is that the mechanistic aspects in some of the biological systems need more detailed studies.

Potential use of silver nanoparticles on pathogenic bacteria, their toxicity and possible mechanisms of action

As propriedades da prata sao conhecidas ha muitos anos. Recentemente, as nanoparticulas de prata tem chamado a atencao por sua atividade antimicrobiana que oferece a possibilidade de uso com propositos medicos e de higiene. Estas nanoparticulas de prata em diferentes formulacoes, com diferentes formas e tamanhos, exibem atividades antimicrobianas diferentes. Entretanto, os mecanismos da atividade antimicrobiana de ions e de nanoparticulas, assim como sua toxicidade em tecidos humanos nao estao totalmente esclarecidos. Esta revisao avalia o uso potencial de nanoparticulas de prata no controle de patogenicos com enfase sobre sua acao contra bacterias patogenicas, sua toxicidade e possiveis mecanismos de acao. The antimicrobial properties of silver have been known for thousands of years. Recently, silver nanoparticles have gained attention because of their antimicrobial activity which offers the possibility of their use for medical and hygiene purposes. Indeed, silver nanoparticles in different formulations and with different shapes and sizes exhibit variable antimicrobial activity. However, the mechanisms of antimicrobial activity of silver ions and silver nanoparticles, and their toxicity to human tissues are not fully characterized. This review evaluates the potential use of silver nanoparticles to control pathogens with emphasis on their action against pathogenic bacteria, their toxicity and possible mechanisms of action.

Chitosan-solid lipid nanoparticles as carriers for topical delivery of tretinoin

Tretinoin (TRE) or all-trans retinoic acid is employed in the topical treatment of various skin diseases including acne and psoriasis. However, its use is strongly limited by side effects and high chemical instability. TRE encapsulation in nanostructured systems reduces these problems. Chitosan is a biopolymer that exhibits a number of interesting properties such as bioadhesion and antibacterial activity. The aim of this work was to prepare and characterize solid lipid nanoparticles (SLN) containing TRE, with and without addition of chitosan, to assess their in vitro cytotoxicity in keratinocytes and to evaluate their antibacterial activity against bacteria related to acne. SLN without (SLN-TRE) and with (SLN-chitosan-TRE) chitosan were prepared by hot high pressure homogenization. The hydrodynamic mean diameter and zeta potential were 162.7±1.4 nm and -31.9±2.0 mV for SLN-TRE, and 284.8±15.0 nm and 55.9±3.1 mV for SLN-chitosan-TRE. The SLN-chitosan-TRE exhibited high encapsulation efficiency, high physical stability in the tested period (one year), were not cytotoxic to keratinocytes and showed high antibacterial activity against P. acnes and S. aureus. Therefore chitosan-SLN can be good candidates to encapsulate TRE and to increase its therapeutic efficacy in the topical treatment of acne.

A New Report on Mycosynthesis of Silver Nanoparticles by Fusarium culmorum

Plant pathogenic fungus Fusarium culmorum (MTCC-2090) assists in the mycosynthesis of silver nanoparticles. Formation of spherical silver nanoparticles was confirmed from TEM analysis and found in the range of 5-25 nm with an average diameter of 11 nm. Different temperature and pH affects the synthesis of silver nanoparticles indicating that synthesis depends significantly on temperature and pH. Formation of silver nanoparticles at room temperature and pH-7 was found to be optimum for synthesis process. The combined effects of mycosynthesized silver nanoparticles with different antibiotics like kanamycin, erythromycin, oxacillin, tetracycline, vancomy- cin and gentamycin against Klebsiella pneumoniae (MTCC-7407) and Enterobacter aerogenes (MTCC-6804) were carried out. Oxacillin showed the maximum increase in fold area as compared to other antibiotics tested against both the test organisms. Fungal proteins are re- sponsible for the synthesis of silver nanoparticles. This process is easy, eco-friendly and scalable for the large scale synthesis of silver nanoparticles. The synthesis of silver nanoparticles by F. culmorum has not been reported in the past, and thus, it is being reported for the first time.

Screening of different Fusarium species to select potential species for the synthesis of silver nanoparticles

Eleven different Fusarium species were isolated from various infected plant materials and screened to select a potential species for the synthesis of silver nanoparticles. All the isolates were identified on the basis of cultural and microscopic characteristics using Fusarium identification keys. For the confirmation of preliminary identified isolates of Fusarium species, online BLAST analysis was carried out. All the eleven species demonstrated the ability for synthesis of silver nanoparticles. This was confirmed by UV-Vis spectroscopy, which gave characteristic peak around 420 nm. Further confirmation of silver nanoparticles was carried out using nanoparticles tracking analysis (NTA), zeta potential, photon correlation spectroscopy (PCS), powder X-ray diffractometry (XRD) and transmission electron microscopy (TEM). The smallest size of silver nanoparticles was synthesized by F. oxysporum (3-25 nm) and largest size silver nanoparticles were synthesized by F. solani (3-50 nm).

Biomedical applications of nanobiosensors: the state-of-the-art

O desenvolvimento de nanobiosensores e um dos avancos mais recentes no campo da nanotecnologia. A investigacao sobre nanobiosensores opticos com dimensoes submicrometricas tem aberto novos horizontes para as medicoes intracelulares. Aproveitando as propriedades unicas dos nanomateriais, nanobiosensores mais rapidos e sensiveis podem ser desenvolvidos. Alem de serem sensiveis e rapidos, os estudos de nanobiosensores tem voltado seus esforcos para o desenvolvimento de sensores baseados em nanomateriais que sao acessiveis, robustos e reprodutiveis. Os nanobiosensores estao equipados com sondas biorreceptoras imobilizadas, por exemplo, anticorpos, substrato de enzima. A excitacao por laser e transmitida para o sistema fotometrico na forma de sinal optico (fluorescencia). Os nanobiosessores poderao revolucionar no futuro o diagnostico de doencas. A presente revisao discute os conceitos basicos, a evolucao e as aplicacoes biomedicas de nanobiosensores. Development of nanobiosensor is one of the most recent advancement in the field of Nanotechnology. Research on optical nanobiosensors with submicron-sized dimensions has opened new horizons for intracellular measurements. Taking advantage of the unique properties of the nanomaterials, faster and sensitive nanobiosensors can be developed. Apart from being sensitive and fast, the studies related to nanobiosensors have geared their efforts towards the development of nanomaterial-based sensors that are affordable, robust and reproducible. The nanobiosensors are equipped with immobilized bioreceptor probes, e.g., antibodies, enzyme substrate. Laser excitation is transmitted to photometric system in the form of optical signal (fluorescence). Nanobiosensors will revolutionize the future of disease diagnosis. The present review discusses the basic concepts, developments and the biomedical applications of nanobiosensors.

Development of a Sustained-release System for Nitric Oxide Delivery using Alginate/Chitosan Nanoparticles

Free radical nitric oxide (NO) has been known to interact with various physiological processes, such as wound repair processes and control of vascular tone. However, NO is an unstable molecule and the development of NO delivery systems that enhance its stability has also been studied. In this work, alginate/chitosan nanoparticles have been studied as a drug delivery system of the S- nitrosoglutathione (GSNO) as NO donor. For this, glutathione, GSH, the GSNO precursor, was encapsulated in alginate/chitosan nanoparticles. The presence of GSNO was confirmed by UV spectra at 336 nm. Alginate/chitosan nanoparticles with negative and posi- tive surface charges were obtained by increasing the chitosan amount. The encapsulation efficiency (EE) relied on the nanoparticle zeta potential, obtaining 80% of EE for positive particles. The NO release from GSNO showed that polymeric nanoparticles lead to the stabi- lization of GSNO decomposition, at physiological temperature. Moreover, this system did not exhibit cytotoxicity for fibroblast V79 cells up to the maximum concentration tested (18 μmolL -1 ). These results showed that alginate/chitosan nanoparticles are interesting particles to encapsulate NO donors for biomedical applications where NO might have a therapeutic effect.

Fungi-Mediated Synthesis of Silver Nanoparticles: Characterization Processes and Applications

The term “nanotechnology” is derived from the Greek word ‘nano’, meaning ‘dwarf’, and applies to the principles of engineering and manufacturing at a molecular level. The common definition of nanotechnology is that of manipulation, observation, measurement and synthesis at a scale of 1 to 100 nanometers (Raj and Asha, 2009). Nanobiotechnology is a new branch of science dedicated to the improvement and utilization of devices and structures ranging from 1 to 100 nm in size, in which new chemical, physical, and biological properties, not seen in bulk materials, can be observed. There is tremendous excitement in this field with respect to their fundamental properties, organization of superstructure and applications.

State of the Art of Nanobiotechnology Applications in Neglected Diseases

The neglected diseases have not received any especial public and private attention in the last years, as for example, some para- sitic diseases. Considerable amounts of private and public money are needed to apply nanobiotechnology for the treatment of neglected diseases. This review focuses on malaria, leishmaniasis, schistosomiasis, trypanosomiasis, tuberculosis, leprosy and filiarasis, and on- chocerciasis where liposomes, polymeric nanoparticles or nanostructured lipid carriers have been applied. These nanocarrier systems have shown promissing results in the treatment of many neglected diseases with diminished toxicity and increased efficacy as well as a prolonged release with a reduced number of dosages. Despite these promising results, few nanocarriers have been used in clinical tests. As far as we know, these references are a minority compared to the number of studies of drug delivery systems that have been published in the last years. Therefore, the challenge for the researchers in this area is to generate interest amongst the governments and industries for the treatment of neglected diseases.