Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: PEG Branched Polymer for Functionalization of Nanomaterials with
  Ultralong Blood Circulation   Nanomaterials have been actively pursued for biological and medical
applications in recent years. Here, we report the synthesis of several new
poly(ethylene glycol) grafted branched-polymers for functionalization of
various nanomaterials including carbon nanotubes, gold nanoparticles (NP) and
gold nanorods (NRs), affording high aqueous solubility and stability for these
materials. We synthesize different surfactant polymers based upon
poly-(g-glutamic acid) (gPGA) and poly(maleic anhydride-alt-1-octadecene)
(PMHC18). We use the abundant free carboxylic acid groups of gPGA for attaching
lipophilic species such as pyrene or phospholipid, which bind to nanomaterials
via robust physisorption. Additionally, the remaining carboxylic acids on gPGA
or the amine-reactive anhydrides of PMHC18 are then PEGylated, providing
extended hydrophilic groups, affording polymeric amphiphiles. We show that
single-walled carbon nanotubes (SWNTs), Au NPs and NRs functionalized by the
polymers exhibit high stability in aqueous solutions at different pHs, at
elevated temperatures and in serum. Morever, the polymer-coated SWNTs exhibit
remarkably long blood circulation (t1/2 22.1 h) upon intravenous injection into
mice, far exceeding the previous record of 5.4 h. The ultra-long blood
circulation time suggests greatly delayed clearance of nanomaterials by the
reticuloendothelial system (RES) of mice, a highly desired property for in vivo
applications of nanomaterials, including imaging and drug delivery.

8
The categories of this paper are: hep-ex
22
The categories of this paper are: chao-dyn
6
The categories of this paper are: astro-ph
5
The categories of this paper are: gr-qc
3
The categories of this paper are: physics
7
The categories of this paper are: hep-th
29
The categories of this paper are: funct-an
31
The categories of this paper are: ao-sci
11
The categories of this paper are: hep-lat
37
The categories of this paper are: supr-con
21
The categories of this paper are: adap-org
33
The categories of this paper are: plasm-ph
34
The categories of this paper are: chem-ph
0
The categories of this paper are: hep-ph
35
The categories of this paper are: mtrl-th
16
The categories of this paper are: stat