Cell penetrating peptide (CPP) has been highlighted for promising potential in cytosolic supply, enabling purposes as carriers to penetrate throughout organic boundaries resembling cell membrane, mucosa, stratum corneum, and blood-brain barrier [1], [2], [3], [4], [5], [6]. These peptides had been extensively employed as supply automobiles for intracellular protein transport [7], [8], [9], [10], [11], through genetic engineering [1], [12], or chemically conjugation [13], [14], [15] onto cargo proteins. The CPP-tagged proteins have proven elevated mobile uptake, however their supply efficacy is normally unsufficient as a result of endosomal entrapment. As well as, the conjugated peptides might have an effect on the bioactivity of cargo proteins as a result of potential steric impact or strengthened intramolecular interactions [13], [16], [17].
In addition to the covalent technique, CPPs might immediately advanced with cargo proteins to kind nanoparticles through ionic and hydrophobic interactions for cytosolic supply [18]. Nonetheless, the fashioned nanoparticles through non-covalent interactions are liable to disassembly as a result of considerable ions and biomacromolecules in physiological circumstances [19], [20], [21], [22], [23], [24]. To strengthen the binding interactions and nanoparticle stability, polymerized CPPs with linear or branched topological constructions had been designed to realize a multivalent impact [25], [26], [27], [28]. Alternatively, hydrophobic motifs resembling alkyl chains or ldl cholesterol had been conjugated to CPPs to arrange amphipathic cationic peptides (ACPs), which might successfully enhance nanoparticle stability through supramolecular meeting [10], [22], [29], [30]. To enhance the endosomal escape functionality, pH-responsive CPPs enabling conformational modifications when entrapped in acidic vesicles, such because the influenza HA fusion area, had been adopted to design the supply service [31], [32]. Moreover, acidic amino acids resembling glutamic acid or aspartic acid residues had been integrated into CPPs to assemble the lipid-sensitive endosomolytic peptide carriers [33], [34].
Our earlier research have demonstrated that fluorination on carriers is an efficient technique to advertise the cytosolic supply of genes and proteins [35], [36], [37]. Conjugation of a fluorous tag to cargo peptides additionally obtain environment friendly and sturdy cytosolic peptide supply through enhanced supramolecular meeting, mobile uptake and endosomal escape [38], [39], [40]. Right here, we suggest to design a kind of fluorinated CPPs for cytosolic protein supply (Fig. 1). A library of amphiphilic cationic peptides (ACPs) was constructed by conjugating a fluorous tag bearing 13 fluorine atoms on the C-terminus to acquire fluorinated ACPs (FACPs). The ACPs within the library initiately designed with arginine- and tryptophan-rich peptides for environment friendly cytosolic protein supply. The cationic amino acid arginine can work together with cargo protein through salt-bridge interactions [41], [42], [43], [44], and promote intracellular supply through the identified “arginine magic” [45], whereas the hydrophobic tryptophan can strongly work together with cell membranes through a number of interactions [19], [46]. The number of the hexa-arginine motif is rationalized by the established precept that 6–8 arginine residues are optimum for mobile internalization, as demonstrated by Futaki and our group [41], [47]. Herein, we intention to develop a novel sort of hexa-peptide carriers for environment friendly and sturdy intracellular protein supply. The structure-function relationships of the FACPs in cytosolic protein supply are intensively investigated. The lead materials FACP2 effectively ship ovalbumin (OVA) into dendritic cells (DCs), stimulate DCs maturation and promote antigen cross-presentation each in vitro and in vivo (Fig. 1). The ready FACP2/OVA nanovaccine considerably inhibited tumor development, stimulated DC maturation, facilitated antigen cross-presentation, and activated antigen-specific T cells.
