Zhanwei Zhou,Chenzi Li,Minghua Zhang,Qingyan Zhang,Chenggen Qian,David Oupicky,Minjie Sun
Hydrophobic modification on polycations were commonly used to improve the stability and transfection efficiency of polyplexes. However, the improved stability often means undesired release of the encapsulated siRNA, limiting the application of cationic micelles for siRNA delivery. The current strategy of preparing bioresponsive micelles based on the cleavage of sensitive linkages between polycation and hydrophobic part was far from sufficient, owing to the siRNA binding of the separated polycations from micelles leading to the incomplete release of siRNA. In this study, we propose a new strategy by the combination of micelles disassembly and separated polycations charge reversal. FPBA (3-fluoro-4-carboxyphenylboronic acid) grafted PEI 1.8 k (polyethylenimine) as the polycations of PEI-FPBA and dopamine (with diol-containing moiety) conjugated with cholesterol as the hydrophobic part (Chol-Dopa). The PFCDM micelles was assembled by PEI-FPBA and Chol-Dopa, based on the FPBA-Dopa conjugation. The prepared PFCDM showed strong siRNA loading ability and superior stability in the presence of PBS or serum. Besides, the PFCDM exhibited excellent ATP sensibility. The intracellular ATP could effectively trigger the disassembly of micelles and charge reversal of PEI-FPBA, resulting in the burst release of siRNA in the cytosol. With the property of extracellular stability and intracellular instability, PFCDM displayed good performance on in vitro and in vivo luciferase silencing on 4T1 cells. It should also be noted that the assembly of low molecular weight PEI was relatively safe to cells compared with 25 k PEI. To sum up, the ATP-fueled assembly and charge reversible micelles gave examples for polyplexes to achieve better stability and on demand cargo release at the same time and shows potential to be used for in vitro and in vivo siRNA transfection.
Epilepsy is characterized by repeated spontaneous seizures and remains untreatable due to its complicate pathogenesis. Low-dose hydrogen sulfide (H 2 S) has been shown to exert antiepileptic and protective effects in the central nervous system, but the administration of H 2 S gas to suppress seizures is difficult. In the present study, we synthesized a safe and efficient carbazole-based H 2 S donor from aldehydes with a one-pot procedure and characterized this specific H 2 S donor via proton nuclear magnetic resonance ( 1 HNMR), scanning electron microscopy (SEM), and absorption spectroscopy. In vitro and in vivo risk assessments demonstrated that the H 2 S donor (up to a 400-μM concentration) had sufficient biocompatibility and membrane permeability and suppressed epileptic seizures. Importantly, the suppression of seizures was determined in the brain when the H 2 S donor was injected into the lateral ventricle in a rat model of advanced seizures. Furthermore, the mechanism by which the H 2 S donor suppressed the expression of seizures may have been related to H 2 S donor-induced increases in the expressions of the ATP-sensitive potassium channel (K ATP ) subunits, Kir6.2 and SUR1. Taken together, these assays suggested that our novel H 2 S donor may represent a potential therapeutic strategy for ameliorating seizures in epilepsy.
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