Pegda 700

FeCl₃·6H₂O (Acros
Organics, 99%), fumaric acid (Acros Organics, 99%), Pluronic F127
(Sigma-Aldrich, average Mw = 12,600 g/mol, Aldrich), acetic acid (Thermo
Scientific, 99.7%), poly(ethylene glycol) diacrylate (Sigma-Aldrich,
average Mn = 250), PEGDA₂₅₀, poly(ethylene glycol) diacrylate
(Sigma-Aldrich, average Mn = 700) PEGDA₇₀₀, TMPTA (Sigma
Aldrich), and diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (Sigma-Aldrich,
97%) were purchased and used without further purification.

GelMA was synthesized and characterized as previously described (Soman et al., 2013 (link)). Polyethylene glycol diacrylate (Mn 700, PEGDA700) was purchased from Sigma-Aldrich. Lithium phenyl-2,4,6-trimethylbenzoylphosphinate (LAP) was synthesized as previously described (Fairbanks et al., 2009 (link)) and was stored under argon at 4°C for use as a photo-initiator. The bioink for scaffold printing comprised 4% (w/v) GelMA, 0.1% (v/v) PEGDA, and 0.6% (w/v) LAP in Dulbecco’s PBS (DPBS, Gibco). For the CPMV/Qβ-laden scaffolds, CPMV/Qβ were first resuspended in DPBS to the designated concentration, and the suspension was used to prepare the bioink. The scaffold was printed layer-by-layer using an in-house digital light projection (DLP) 3D bioprinter, which consists of a blue light source (405 nm), a digital micromirror array device for optical pattern generation, a set of projection optics, a motorized stage to guide the fabrication of each layer, and a computer control system. For each layer, a user-defined blue light pattern was projected on the bioink reservoir and only the illuminated area was polymerized. After one layer was polymerized, the stage was lifted by the designated layer thickness, where bioink refilled the gap and allowed the fabrication of the subsequent layer.

Polyvinylpyrrolidone (PVP, average molecular weight 10,000 g/mol), L-ascorbic acid (vitamin C, ≥99%, ACS reagent), diacrylate poly(ethylene glycol) (PEGDA 575—average molecular weight 575 g/mol and PEGDA 700—average molecular weight 700 g/mol), and 2-hydroxy-2-methylpropiophenone (97%) were bought in Sigma Aldrich (Saint Louis, MO, USA). In turn, Aloe vera juice (100%) was purchased from Herbal Pharmaceuticals (Krakow, Poland). All reagents were applied as received without further purification.

PEDOT:PSS solutions (Clevios PH 1000) were purchased from Heraeus, Hanau, Germany, which had a PEDOT:PSS ratio of 1:2.5. Acetone and ethylene glycol from Fisher Scientific, Fair Lawn, NJ, USA; isopropyl alcohol, methanol, and ethanol from EMD Millipore, Billerica, MA, USA; PEGDA-700, benzophenone, sodium periodate (⩾99.8%), and benzyl alcohol (anhydrous, 99.8%) from Sigma-Aldrich, St. Louis, MO, USA, were used as received. The mass ratio of base to curing agent of PDMS (Sylgard 184, Dow Corning, Auburn, MI, USA) was chosen to be 10:1. The prepolymers were mixed and then cured at 120 °C for 30 min. A commercial PEDOT:PSS conducting film (Kodak, Rochester, NY, USA) was used for comparison³⁷ .

The mixture of PEGDA 700 (M_n = 700, SigmaAldrich, St. Louis, MO, USA), PEGDA 250 (Mn = 700, Sigma Aldrich, St. Louis, MO, USA), and sodium alginate (Macklin Chemical Reagent Shanghai Co., Ltd, Shanghai, China) (1 wt%) aqueous solution (Na-Alginate) was used as the inner phase fluid. 2-Hydroxy-2-methylpropiophenone (2% v/v) was added into the mixture of PEDGA 700 and PEDGA 250 as the photoinitiator for UV light curing. Poly (vinyl alcohol) (PVA) (97.5–99% hydrolyzed, Aladdin Reagent Shanghai Co., Ltd, Shanghai, China) was added into deionized water (DI) to achieve a concentration of 5 wt% to be used as the continuous phase fluid. Doxorubicin hydrochloride (DOX) was used as a model drug. Simulated gastric fluid (SGF, pH = 1.2, Shanghai Yuanye Bio-Technology Co., Ltd. Shanghai, China) and simulated intestinal fluid (SIF, pH = 7.2, Shanghai Yuanye Bio-Technology Co., Ltd. Shanghai, China) were used to simulate the environment of the human digestive tract in the drug release experiment. Silicone oil (Aladdin Reagent Shanghai Co., Ltd, Shanghai, China; 20 mPa.s) was used as the oil phase to obtain homogeneous “cup-shaped” microparticles.