Objective:　To　improve　solubility　and　to　reduce　aggregation,　ZnPcC4　was　conjugated　to　a　third-generation　poly-amidoamine　dendrimer　with　amino　end　group　(G3-PAMAM-NH2),　which　acts　as　a　novel　photodynamic　therapy　(PDT)　drug　carrier　system.　Methods:　The　phthalocyanines　were　synthesized　by　construction　reaction.　The　nano　drug　was　obtained　from　the　conjugation　of　ZnPcC4　to　G3-PAMAM-NH2,　using　EDC　and　NHS　as　coupling　agents.　The　ZnPcC4@G3-PAMAM-NH2　conjugation　was　characterized　by　UV-Vis　and　MS.　The1O2　quantum　yield　of　ZnPcC4@G3-PAMAM-NH2　in　water　was　measured　by　the　chemiluminescence　method.　The　in　vitro　PDT　responses　of　the　studied　photosensitizers　were　studied　in　hepatocellular　carcinoma　cell　line　HepG2　by　MTT　assay.　Results:　At　ZnPcC4/G3-PAMAM-NH2　raw　ratio　of　100/1,　the　ZnPcC4　conjugate　had　improved　solubility　and　reduced　aggregation　tendency　in　aqueous　solution.　At　this　optimum　molar　ratio,　ZnPcC4-G3-PAMAM-NH2　inhibited　HepG2　cells,　with　a　half-maximal　inhibitory　concentration　of　1.67　μg/mL　upon　infrared　light　exposure.　The　controls,　including　dark　conditions,　or　media　as　well　as　G3-PAMAM-NH2　exposure,　exhibited　no　inhibitory　response.　Conclusion:　The　conjugation　of　phthalocyanine　photosensitizerZnPcC4　topoly-amidoamine　dendrimer　G3-PAMAM-NH2　improved　the　PDT　outcomes,　in　which　the　optimized　binding　ratio　of　ZnPcC4　to　G3-PAMAM-NH2　was　6:1.　©　2019　Bentham　Science　Publishers.