Phase Behavior of Poly(sulfobetaine methacrylate)-Grafted Silica Nanoparticles and Their Stability in Protein Solutions

Abstract

Biocompatible and zwitterionic poly(sulfobetaine methacrylate) (PSBMA) was grafted onto the surface of initiator-modified silica nanoparticles via surface-initiated atom transfer radical polymerization. The resultant samples were characterized via nuclear magnetic resonance, Fourier transform infrared spectroscopy, transmission electron microscopy, and thermogravimetric analysis. Their molecular weights and molecular weight distributions were determined via gel permeation chromatography after the removal of silica by etching. Moreover, the phase behavior of these polyzwitterionic-grafted silica nanoparticles in aqueous solutions and stability in protein/PBS solutions were systematically investigated. Dynamic light scattering and UV-visible spectroscopy results indicate that the silica-g-PSBMA nanoparticles exhibit an upper critical solution temperature (UCST) in aqueous solutions, which can be controlled by varying the PSBMA molecular weight, ionic strength, silica-g-PSBMA nanoparticle concentration, and solvent polarity. The UCSTs shift toward high temperatures with increasing PSBMA molecular weight and silica-g-PSBMA nanoparticle concentration. However, increasing the ionic strength and solvent polarity leads to a lowering of the UCSTs. The silica-g-PSBMA nanoparticles are stable for at least 72 h in both negative and positive protein/PBS solutions at 37 °C. The current study is crucial for the translation of polyzwitterionic solution behavior to surfaces to exploit their diverse properties in the development of new, smart, and responsive coatings.

Tunable Dual‐Thermoresponsive Phase Behavior of Zwitterionic Polysulfobetaine Copolymers Containing Poly(N,N‐dimethylaminoethyl methacrylate)‐Grafted Silica Nanoparticles in Aqueous Solution

“…Initiator‐functionalized silica nanoparticles were synthesized according to previously reported procedures (see Supporting Information). The average diameter of the initiator‐functionalized silica nanoparticles was determined to be approximately 50 nm by TEM (Figure b).…”

“…The molecular weights of the grafted copolymer, which was cleaved via HF aqueous solutions from silica nanoparticles, increase from 7.26 × 10 4 g mol −1 to 9.87 × 10 4 g mol −1 with SBMA contents from 20 mol% to 70 mol% (Table ). Based on our previous studies, there is no hydrolysis of grafted copolymer chains treated by HF solution. According to the GPC trace of the S50 sample, the molecular weight is 8.54 × 10 4 g mol −1 and the polydispersity index (PDI) is 1.43 (Figure S2, Supporting Information).…”

Zwitterionic‐Coated “Stealth” Nanoparticles for Biomedical Applications: Recent Advances in Countering Biomolecular Corona Formation and Uptake by the Mononuclear Phagocyte System

“…Ji and co‐workers have grafted poly(sulfobetaine methacrylate) (PSBMA) onto silica nanoparticles via surface‐initiated ATRP to produce ca . 120 nm‐sized particles with a Zeta potential of –‐7.5 mV under salt‐free conditions (the slightly negative surface charge was attributed incomplete coverage of the negatively‐charged silica surface) (structure 18 , Figure ) . The particles were stable for at least 72 h in solutions of positive‐ and negatively‐charged proteins, as well as phosphate‐buffered saline (PBS).…”

Zwitterionic ceramics for biomedical applications

“…The most widely used method to graft zwitterionic polymers to bioceramic surfaces is the surface-initiated atom transfer radical polymerization (SI-ATRP) [38]. This method has been used to coat silica NPs with poly(sulfobetaine) (pSB) (structure 6, Figure 2) [39] and polycarboxybetaine (pCB) derivatives [40,41]. Alternatively, surface reversible addition-fragmentation chain transfer (RAFT) polymerization has been used to graft SB copolymers from mesoporous silica nanoparticles (MSNPs) [42].…”