Banca de QUALIFICAÇÃO: RONY LUCAS DA SILVA VIANA

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : RONY LUCAS DA SILVA VIANA
DATE: 11/04/2022
TIME: 14:00
LOCAL: Videoconferência - Link para acesso: https://meet.google.com/emz-dqai-sxd
TITLE:

Silver nanoparticles containing xylans: synthesis, characterization and evaluation of their immunomodulatory and antibacterial effect

KEY WORDS:

Corn cob; Green synthesis; Bacterial resistance; nanotechnology.

PAGES: 100
BIG AREA: Ciências Biológicas
AREA: Bioquímica
SUMMARY:

In recent decades, the increase in bacterial resistance to conventional treatments has led to an incessant search for new effective alternatives against diseases caused by these microorganisms. Within this context, significant progress has been achieved in the development of drugs based on nanotechnology in order to combat/attenuate bacterial resistance. And among the nanoparticles, those made of silver (NANO) are pointed out as a promising option in this sense, including being already applied in different uses, such as in the textile industry. However, their use in clinical medicine has a smaller dimension, and this has been driving the development of different mixed NANO, which contain, in addition to silver, an organic portion in their constitution, since this can enhance or provide new applicability to NANO. This has even allowed the use of techniques less aggressive to the environment (green synthesis) for the synthesis of NANO. Polysaccharides are one of the organic molecules that have been used in this sense. Xylan is a hemi-cellulose found in different plants and, therefore, very abundant in nature. However, there are less than a dozen papers with NANO containing xylans, and none have evaluated their antimicrobial effect. Therefore, in this work NANO was synthesized with different xylans extracted from corn cob (Zea mays). For this, corn cob, in 0.1M NaOH, was subjected to ultrasound waves to obtain a xylan-rich extract (EBX), which was subsequently fractionated with the addition of increasing volumes of ethanol. Thus, six ethanolic fractions (EF's) were obtained, which after being characterized (sugar content, proteins, phenolic compounds, and monosaccharide composition), were used for the green synthesis of NANO. These NANO were characterized by UV-visible spectroscopy, scanning electron microscopy, dynamic light scattering, energy scattering spectroscopy and infrared spectroscopy. All NANO (NANO EBX, NANO E0.3, NANO E0.4, NANO E0.8, NANO E1.4 and NANO E2.2) were essentially composed of silver and xylans, presented round shape, average size ranging from 105, 0 and 79.7 nm and stability of 24 months. These NANO were not cytotoxic against fibroblast (3T3) and macrophages (RAW). Furthermore, they promoted the reduction of nitric oxide (NO) production in macrophages activated by bacterial lipopolysaccharide. The different NANOs, synthesized here, also showed antibacterial activity. All were effective against Gram-negative bacteria tested (Escherichia coli; carbapenemase-producing Klebsiella pneumoniae – KPPC) with emphasis on NANO EBX and NANO E1.4, which showed a minimum inhibitory concentration (MIC) of 62.5 µg/mL against E. coli. For KPPC, NANO EBX, NANO E0.4, NANO E1.4 and NANO E2.2 stand out, which presented a MIC of 250 µg/mL. The data presented here show the biotechnological potential of the different xylans in the form of nanoparticles and future tests, including in vivo, should be carried out to confirm the antibacterial potential of the different NANO synthesized with EBX and FE's.

BANKING MEMBERS:
Presidente - 1549705 - ADRIANA FERREIRA UCHOA
Interno - 3060683 - LEONARDO THIAGO DUARTE BARRETO NOBRE
Externa à Instituição - DAYANNE LOPES GOMES - UFRN