Application of Zwitterionic Polymer Hydrogels to Optical Tissue Clearing for 3D Fluorescence Imaging

Abstract

Zwitterionic polymers have both anion and cation groups in the side chain and have been used in various biomedical applications because of the unique properties. In this study, zwitterionic polymer hydrogels are applied to optical tissue clearing for 3D fluorescence imaging. Polyacrylamide hydrogels have been employed in Clear Lipid‐exchanged Acrylamide‐hybridized Rigid Imaging/Immunostaining/In situ‐hybridization‐compatible Tissue‐hYdrogel method. Zwitterionic polymer hydrogels are produced using zwitterionic monomers, such as 3‐[(3‐acrylamidopropyl)dimethylammonio]propane‐1‐sulfonate (DAPS) and 2‐methacryloyloxyethyl phosphorylcholine (MPC), and crosslinkers. The hydrogels made from poly(DAPS‐co‐acrylamide) and MPC homopolymers afford the most transparent tumor tissues. However, the tissues cleared using DAPS copolymers‐containing hydrogels became turbid in a refractive index‐matching solution, which are unable to obtain clear 3D fluorescence images. In contrast, the 3D fluorescence imaging is achieved in the MPC polymer‐treated 2‐mm‐thick brain slices after immunostaining. The 3D fluorescence imaging of lung metastasis that is cleared by the MPC hydrogel to demonstrate the possible application to cancer diagnosis is performed. The results indicate the increased potentials of zwitterionic polymer hydrogels, especially MPC polymer hydrogels, in biomedical applications.

Antibacterial-Based Hydrogel Coatings and Their Application in the Biomedical Field—A Review

“…We can classify antibacterial hydrogel coatings into two categories according to the type of active ingredients. The first is compositions containing antibacterial substances, such as natural or synthetic cationic polymers [28,29], amphoteric polymers [30], and antibacterial peptides [31]. The second is loaded antibacterial substances, such as antibiotics [32], antibacterial analogues [33], nano-silver [34], and zinc oxide, in the three-dimensional hydrogel network [35].…”

In vivo transfection of cytokine genes into tumor cells using a synthetic vehicle promotes antitumor immune responses in a visceral tumor model

“…For 3D fluorescence imaging, after rinsing with PBS, the fixed samples were cleared using tetraethylene glycol dimethacrylate-crosslinked 2-methacryloyloxyethyl phosphorylcholine polymer hydrogel, as described previously. 12 The cleared tissues were incubated with propidium iodide (PI) (Thermo Fisher Scientific, Tokyo, Japan) to visualize cell nuclei and the following Abs: rabbit anti-mouse CD11c monoclonal Ab (mAb) (clone EPR21826, Abcam, Cambridge, UK, Cat# ab219799, RRID:AB_2864725) to detect DCs, rabbit anti-human Granzyme B Ab (Abcam, Cat# ab4059, RRID:AB_304251) to detect killer cells, rabbit anti-mouse CD4 mAb (clone CAL4, Abcam, Cat# 237722) to detect helper T cells, rat anti-mouse FoxP3 mAb (clone FJK-16s, Thermo Fisher Scientific, San Diego, CA, USA, Cat# 14-5773-80, RRID:AB_467575) to detect regulatory T cells (Tregs), rat anti-mouse programmed death-1 (PD-1) mAb (clone RMP1-14, Leinco Technologies, St. Louis, USA, Cat# P362, RRID:AB_2737557), and rabbit anti-human programmed death ligand-1 (PDL-1) Ab (Proteintech, Cat# 17952-1-AP, RRID:AB_10597552) to detect immune checkpoint molecule-expressing cells. Ab-incubated products were visualized using fluorescein isothiocyanate-labeled F(ab')2-Goat anti-rabbit IgG (H+L) Ab (Invitrogen) or Alexa Fluor 647-labeled goat anti-rat IgG (H+L) Ab (Invitrogen).…”

Recent progress and perspectives in applications of 2-methacryloyloxyethyl phosphorylcholine polymers in biodevices at small scales

“…Generally, there are two primary applications of surface coatings of MPC polymers: (1) quantitative analysis of biological samples such as tears, serum, and urine, 49–56 and (2) semi-quantitative or qualitative analysis for disease diagnosis. 57–63…”

“…Generally, there are two primary applications of surface coatings of MPC polymers: (1) quantitative analysis of biological samples such as tears, serum, and urine, [49][50][51][52][53][54][55][56] and (2) semiquantitative or qualitative analysis for disease diagnosis. [57][58][59][60][61][62][63] Several publications have reported the advantages of coating a standard electrode with MPC polymers, which can significantly increase binding selectivity and decrease noise during measurements because of their ability to prevent NPA. 51,52,54,55,64 For instance, Li et al synthesized poly(MPC-co-VPBA-co-vinylferrocene (VFC)) (referred to as PMVF in ref.…”

“…The MPC-modified surface can resist NPA, enabling efficient semi-quantitative or qualitative analysis such as image analysis for disease diagnosis or for observation of an area inside the body without surgery. [57][58][59][60][61][62][63] For example, Yudasaka et al replaced sodium deoxycholate on the surface of single-walled carbon nanotubes (CNTs) by poly(MPC-co-BMA) (referred to as PMB) using ultrafiltration. 69 The obtained PMB-coated CNT emits near-infrared (NIR) fluorescence at wavelengths of 1100-1400 nm.…”