Micellization and Single-Particle Encapsulation with Dimethylammoniopropyl Sulfobetaines

Abstract

Sulfobetaines (SBs) are a class of zwitterionic surfactants with a reputation for enhancing colloidal stability at high salt concentrations. Here, we present a systematic study on the self-assembly of SB amphiphiles (sultaines or hydroxysultaines) in aqueous solutions, as a function of chain length and composition, ionic strength, and in the presence of alkanethiol-coated Au nanoparticles (GNPs). The diameters of the micelles assembled from SB and amidosulfobetaine (ASB) generally increase monotonically with chain length, although ASB micelles are smaller relative to alkyl SB micelles with similarly sized tailgroups, and oleyl sulfobetaine (OSB) micelles are slightly larger. SB amphiphiles can stabilize alkanethiol-coated GNPs in physiologically relevant buffers at concentrations well below their CMC, with size increases corresponding to single-particle encapsulation. SB-encapsulated GNPs were prepared by three different methods with SB:GNP weight ratios of 10:1, followed by dispersion in water or 1 M NaCl. The low hydrodynamic size of the SB micelles and SB-coated NPs is within the range needed for efficient renal clearance.

Nanoparticle induced formation of self-assembled zwitterionic surfactant microdomains which mimic microemulsions for the in situ fabrication and dispersion of silver nanoparticles

“…19,20 For instance, the surfactant SB3-10 (same formula as C 10 -APSO 4 except the terminal anionic group is sulfonate, -SO 3 , rather than sulfate) has a diameter of only 2-4 nm. 19,20 Although a C n -APSO 4 surfactant is neutral overall, the zetapotential of the solution including this surfactant at pH 3 (without Ag-NPs) was determined to be +23.2, +10.2 and À20.0 mV for C 8 -, C 9 -, and C 10 -APSO 4 respectively. These values are in the range of reported values for other zwitterionic surfactant systems which can range from slightly positive to À70 mV depending upon the type and concentration of added salts and pH.…”

siRNA Delivery Using Dithiocarbamate-Anchored Oligonucleotides on Gold Nanorods

“…To prevent the aggregation of GNRs at high ionic strength (I ≥ 0.5 M), we examined a suite of zwitterionic surfactants with sulfobetaine (SB) or amidosulfobetaine (ASB) headgroups, which are known to form stable micelles under these conditions. 59 Citrate-stabilized GNRs were centrifuged and dispersed twice in 0.1 M NaCl with millimolar amounts of SB surfactant, then adjusted with brine to an ionic strength of 0.5 or 1.0 M. Several amphiphiles (ASB-14, ASB-16, C18-SB, and OSB) were able to stabilize GNRs in 1 M NaCl with over 90% retention of optical density after one day and 80% retention after one week ( Figure S2, Supporting Information). These zwitterionic surfactants were assessed for potential offtarget toxicity using mitochondrial activity assays with SKOV-3 cells, hepatic HepaRG cells, and two kidney cell types (MDCK and LLC-PK1).…”

“…All were found to be less toxic than CTAB by one to two orders of magnitude, with IC 50 values well above the level of residual surfactant after siRNA loading (Table 1 and Figure S3, Supporting Information). Among these, we selected OSB for its relatively good solubility in both low and high salt solutions, 59 and also for the stability of OSB-coated GNRs against shear stress which enabled their efficient recovery after centrifugation.…”

“…58 In this paper, we present a method for loading siRNA duplexes onto GNRs using DTC chemistry and demonstrate their receptor-mediated uptake by SKOV-3 cells, a drug-resistant ovarian cancer cell line, with light-triggered siRNA release and efficient knockdown of two target gene products. siRNA loading is performed in a single step by using oleylsulfobetaine (OSB), 59 a novel zwitterionic surfactant, to maintain colloidal stability at high ionic strength. The stability and release profiles of DTC-siRNA are compared against that of iminothiolate-siRNA, using pulsed or CW laser irradiation for photothermal activation.…”

6,7-Dihydro-5H-pyrrolo[1,2-a]imidazole

“…Ionic liquids have emerged as a promising area in material science because of their tunable properties, allowing them to be used in a wide range of application such as: carbon dioxide capture, fuel cells, nanoparticle stabilization, and many more (Song et al, 2019;Huang et al, 2017;Wang et al, 2017). In this context, our group has been working on the synthesis of new cation moieties for ionic liquid designs.…”