Table 6.

Effect of NPs surface charge on tumor uptake: it seems that positively charged NPs and slightly negative display a good tumor uptake.

Authors	Nanoparticle types and charge	Treatment/study	Efficacy
Xiao et al. [44]	NPs with high negative and high positive charge	Tumor cellular uptake	High uptake of slight negative and slight positive NPs
Gou et al. [111]	NPs with different charge	Tumor cell uptake	Delayed charge reversal strategy could improve therapeutic effect
Graf et al. [112]	High positive NPs	Stability in physiological media	Effective cellular internalization
He et al. [45]	Polymeric NPs negative(−40 mV) and positive charge (+35 mV)	Tumor uptake	Slight negative charge accumulate more efficiently in tumor
Chen et al. [113]	Positive and negative NPs	Tumor uptake	High uptake of positively charged Nps increase uptake of both charge under hypoxic conditions
Stylianopoulos et al. [105]	Positive NPs switched into neutral inside the tumor	Cancer (tumor targeting)	Positive NPs: Effective tumor targeting & neutral charge allowed quicker diffusion of the nanoparticles to the tumor tissue