Electroactive Nanogel Formation by Reactive Layer-by-Layer Assembly of Polyester and Branched Polyethylenimine via Aza-Michael Addition

Oyku Yildirimkaraman, Sezer Özenler, Ufuk Saim Gunay, Hakan Durmaz, Ümit Hakan Ylldlz*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

10 Citations (Scopus)


We here demonstrate the utilization of reactive layer-by-layer (rLBL) assembly to form a nanogel coating made of branched polyethylenimine (BPEI) and alkyne containing polyester (PE) on a gold surface. The rLBL is generated by the rapid aza-Michael addition reaction of the alkyne group of PE and the -NH2 groups of BPEI by yielding a homogeneous gel coating on the gold substrate. The thickness profile of the nanogel revealed that a 400 nm thick coating is formed by six multilayers of rLBL, and it exhibits 50 nm roughness over 8 μm distance. The LBL characteristics were determined via depth profiling analysis by X-ray photoelectron spectroscopy, and it has been shown that a 70-100 nm periodic increase in gel thickness is a consequence of consecutive cycles of rLBL. A detailed XPS analysis was performed to determine the yield of the rLBL reaction: the average yield was deduced as 86.4% by the ratio of the binding energies at 286.26 eV, (C=CN-C bond) and 283.33 eV, (CC triple bond). The electrochemical characterization of the nanogels ascertains that up to the six-multilayered rLBL of BPEI-PE is electroactive, and the nanogel permeability had led to drive mass and charge transfer effectively. These results promise that nanogel formation by rLBL films may be a straightforward modification of electrodes approach, and it exhibits potential for the application of soft biointerfaces.

Original languageEnglish
Pages (from-to)10902-10913
Number of pages12
Issue number37
Publication statusPublished - 21 Sept 2021

Bibliographical note

Publisher Copyright:
© 2021 American Chemical Society.


S.Ö. is a YÖK 100/2000 scholarship holder. The authors would like to acknowledge the support of the Scientific and Technological Research Council of Turkey (TUBITAK) 2214-A International Doctoral Research Fellowship Programme for Ph.D. Students. XPS point and depth profiling analysis were performed at Ege University Central Research Testing and Analysis Laboratory Research and Application Center (EGE-MATAL). We are thankful to Dr. Ayşegül Erdoğan for the fruitful discussion of XPS data.

FundersFunder number
Türkiye Bilimsel ve Teknolojik Araştirma Kurumu


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