Table 2.

Recent Applications of Representative CPPs in vitro

Applications of Representative CPPs in Proteins Delivery
CPPs	Sequences	Cargo	Target	Summary
TAT	YGRKKRRQRRR	JNKI	Neurons	TAT-JNKI administration 6 hours after oxygen glucose deprivation reduced neurons death at 24 hours [78]
Applications of Representative CPPs in Nucleic Acids Delivery
Name	Sequences	Cargo	Target	Summary
TAT	YGRKKRRQRRR	Plasmid DNA	Various cell lines	Confocal imaging showed that TAT-DNA mediated transfection was 3-fold more efficient than a standard PEI transfection [85]
HC-[poly(K)]	QYIKANSKFIGITEL-poly(K)	Plasmid DNA	Neuroblastoma / glioma mouse/rat hybrid cell line	HC-[poly(K)]-DNA, resulting in non-viral gene delivery and marker gene expression in vitro, was dependent on HC and was neuronal cell type specific [86]
RVG-9R	YTIWMPENPRPGTPCDIFTNSRGKRASNG-9R	FvE siRNA	Neuronal cells	RVG-9R delivered FvE siRNA to the neuronal cells, resulting in specific gene silencing within the brain, and afforded robust protection against fatal viral encephalitis in mice [66]
Penetratin	RQIKIWFQNRRMKWKK	Caspase-3/8/9 siRNA, SOD1-1/2 siRNA	Primary mammalian hippocampal and sympathetic neurons	Penetratin-caspase-3i/8i/9i siRNA can be uptake by primary mammalian hippocampal and sympathetic neurons efficiently; Penetratin-thiol linker-deliver  SOD1-1/2 siRNA to neurons simply, efficiently, and without toxicity [99]
TP/TP10	GWTLNSAGYLLGKINLKALAALAKKIL/AGYLLGKINLKALAALAKKIL	NFкB decoy DNA	Various cell lines	Conjugation of TP/TP10-PNA hexamer or nonamer with NFкB decoy DNA can efficiently depress interleukin-1-induced NFкB activation and interleukin-6 gene expression [104]
Applications of Representative CPPs in Small-Molecule Drugs Delivery
CPPs	Sequences	Cargo	Target	Summary
Angiopep-5	RFFYGGSRGKRNNFRTEEY	Doxorubicin	Brain cancer cells	Angiopep-5-doxorubicin killed brain cancer cell lines in vitro [113]
SynB3	RRLSYSRRRF	Morphine-glucuronide	Brain cancer cells	SynB3 enhanced the brain uptake of morphine-glucuronide through an in vitro BBB model [52]
Applications of Representative CPPs in Nanoparticles Delivery
CPPs	Sequences	Cargo	Target	Summary
TAT-PEG-Cholesterol	YGRKKRRQRRR- PEG-Cholesterol	FITC	Brain astrocytes cells	Confocal laser scanning microscopy reveals that the uptake of FITC-TAT-PEG-Cholesterol by human astrocytes was much higher than that of free FITC [119]
PAMAM-PEG- Angiopep-2	PFFYGGSGGNRNNYLREEY	Plasmid DNA	Brain glial cells	PAMAM-PEG-DNA-Angiopep-2 can be a potential delivery system for gene therapy of glial tumor [124]
PEI-TAT	YGRKKRRQRRR-PEI	Plasmid DNA	Primary neurons	PEI-DNA-TAT improves the cellular uptake of gene vectors and enhances the gene transfection efficiency of primary neurons up to 14-fold [90]