Kyoungja Woo

Synthesis & Antimicrobial Efficacy of Magnetic Silica Microspheres Decorated with AgNPs

10th U.S.-Korea Nano Forum, Boston, MA, Oct 15-16, 2013

Needs for Virus Removal System

(Air, Water)

OUTBREAKS OF VIRAL INFECTION !

SOCIAL DEMAND

Nano Convergent Materials Tech.

Motivation of the Project

AgNP interaction with bacterial cells

1) Release Ag+ and generate ROS 2) Interact with membrane protein 3) Accumulate in the cell membrane 4) Enter into the cell

J. Nanopart. Res. (2010) 12:1531

AgNPs

The smaller, the better

AgNP interaction with microbial membranes

The AgNPs bind to the gp120 knobs (cysteine location) of HIV virus

Journal of Nanobiotechnology 2005, 3:6

AgNP(<10 nm) & HIV-I

Degradation of the membrane Structure

Journal of Colloid and Interface Science 2004, 275, 177

AgNP(~12 nm) & E. Coli

b

d

Major challenges in practical utilization of AgNPs 1. Aggregation of AgNPs

2. Environmental release of AgNPs

* The smaller, the better?

Organic Polymer-AgNP Composite

Polysulfone ultrafiltration membrane impregnated with AgNP (Membrane fabrication: 15% PSf, 10% PVP, 75% NMP, 0.9% AgNP)

without AgNP

with AgNP

After filtration of 0.4 L/cm2, 10% AgNP loss !

Water Research 2009, 43, 715

▪ Magnetic hybrid colloid decorated with AgNP (AgNP@MHC)

Inorganic Superparamagnetic AgNP Composite

Inorganic Superparamagnetic AgNP@MHC

S. Coverage: 8.8% 25% 18%

Inorganic Superparamagnetic Ag/Au@MHC

XPS analysis of Ag/Ag@MHC

Fe 3 O 4

Silica

AP

+

+ +

+

+

+

+ +

+ +

+

nAg30@MHC

Ag 3d5/2, 3d3/2 N 1s

AP@MHC + Ag+

AP@MHC

▪ Repeatedly usable noble metal nanocatalyst composite

Catalytic Property of Ag/Au@MHC

ka = 0.095/min TOF(nAg/Au@MHC) = 3.8×10-3/s TOF(chitosan-AgNP5nm) = 0.97×10-3/s

Sci. Rep. 2013, 3, 1497, Woo

Ag/Au@MHC

Antimicrobial effects of AgNP@MHC

E. Coli CN13 Bacteriophage MS2

E.coli CN13+Ag30@MHC as-prepared

E.coli CN13 E.coli CN13+Ag30@MHC @30 min

E.coli CN13+Ag30@MHC @60 min

AgNP@MHC bites away bacteria

AgNP@MHC chemisorbs viruses (Bacteriophage MS2)

Tyr230

Asn228

His181

Arg226

Glu213 Asp94

Arg226

Glu213

His181

Asn228

Asp94 Tyr230

Influenza viral HA structure (interactions at the dimer interface)

from Prof. Kyunghyun Kim in Korea University

Mechanistic study for antimicrobial effects of AgNP (30 nm)

(A) (B) (C)

1 h 1 d

Scale-up synthesis for practical application

TEOS

Acknowledgment Fund: Ministry of Science, ICT & Future Planning through NRF of Korea (GNT program), KIST People: Dr. Hye Hun Park (KIST), Ms. Mihwa Seo (KIST), Dr. Jae-Pyoung Ahn (KIST), Mr. SungJun Park (SNU), Prof. GwangPyo Ko (SNU) Mr. Yoonhaeng Cho (Yonsei U.) Prof. Jeongho Hwang (Yonsei U.)

Thank you !