Application Of Tumor PH-responsive Polyaniline In Diagnosis And Treatment Of Tumors

Tumor-microenvironment-responsive theranostics agents exhibits great potential for precision diagnosis and effective treatment of cancer.Polyaniline(PANI)is the first reported pH-responsive organic photothermal agent and is widely used as a theranostic agent.However,tumor pH-responsive PANI-based theranostic agents are not explored,mainly because the conversion from the emeraldine base(EB)to emeraldine salt(ES)state of PANI requires pH < 4,which is lower than tumor acidic microenvironment(5.4 <pH <7.0).To solve the problem,the assembly of biocompatible bovine serum albumin(BSA)and PANI was constructed,which there is an intermolecular acid–base reactions between carboxyl groups of bovine serum albumin(BSA)and imine moieties of PANI.Thus,the albumin/PANI assemblies(BSA–PANI)can convert from the EB to ES state at pH < 7,The details as follows:Firstly,a tumor pH-responsive PANI based theranostic agent is designed and prepared for amplified photoacoustic imaging guided augmented photothermal therapy(PTT).The albumin/PANI assemblies(BSA–PANI)can convert from the EB to ES state at pH < 7,accompanied by the absorbance redshift from visible to near-infrared region.Both in vitro and in vivo results demonstrate that tumor acidic microenvironment can trigger both the photoacoustic imaging(PAI)signal amplification and the PTT efficacy enhancement of BSA–PANI assemblies.This work not only highlights that BSA–PANI assemblies overcome the limitation of low-pH protonation,but also provides a facile assembly strategy for a tumor pH-responsive PANI-based nanoplatform for cancer theranostics.Secondly,Precise pH detection in tumors can guide the design of pH-responsive drugs and theranostic agents to improve treatment efficacy.Thus,a pH-responsive polyaniline–bovine serum albumin(BSA)probe was constructed for photoacoustic imaging in tumors.The probe can be used to generate high-resolution images of deep biological tissues.The photoacoustic signal of the polyaniline–BSA probe exhibits a clear linear relationship with pH in the range of 5–6.8 both in vitro and in vivo,indicating that the probe is ideal for precise pH detection in most tumors.The polyaniline–BSA probe also exhibits satisfactory biocompatibility,low toxicity,fast response,and good reversibility.This work provides a useful in vivo pH probe for developing pH-responsive drugs and theranostic agents.