Reversible Addition-fragmentation Chain Transfer Research Articles

The crosslinking and decrosslinking of fluorinated diblock copolymer from RAFT emulsion polymerization toward surface anti‐icing

AbstractHere, we demonstrate disulfide‐crosslinked polyfluoroacrylate AB block copolymer films with excellent anti‐icing properties. The fluorinated latexes of AB block copolymers were synthesized via two‐step reversible addition‐fragmentation chain‐transfer (RAFT) emulsion polymerization using polyacrylic acid and its sodium salts as the hydrophilic A‐block, and polyhexafluorobutyl acrylate as the hydrophobic B‐block. Diacetone acrylamide was copolymerized in different blocks as a crosslinking anchor. A disulfide‐containing compound dithiodipropionic acid dihydrazide was chosen as the crosslinking agent to form disulfide‐crosslinked fluorinated films to enhance the mechanical properties, surface properties, swelling properties, and anti‐icing properties of the films. It has proved that the crosslinking site has a great impact on the film formation process which in turn affects the film performance. The B‐block crosslinked films showed better resistance to water while the A‐block crosslinked films were more organic solution resistant. The A‐block crosslinked films also possessed better anti‐icing properties due to the high F/O value. Furthermore, decrosslinking experiments were conducted using a reductant tris(2‐carboxyethyl)phosphine hydrochloride to break the disulfide bond. The recycling rate of the B‐block crosslinked films could reach >90% while the recycling rate of the A‐block crosslinked films reached >75%.

Radical ring-opening polymerization towards degradable polymer as chain extender for polylactic acid

Degradable polymer materials have gained considerable research efforts nowadays. However, widely utilized polymeric chain extenders for degradable polymer materials are mainly nondegradable, where their degradability is ignored. Here, degradable polymeric chain extender for polylactic acid is designed via versatile radical ring-opening polymerization (rROP), by facilely incorporating of labile ester group into main chain of polymeric chain extender. Through reversible addition-fragmentation chain transfer rROP of cyclic ketene acetal as comonomer, a series of epoxy group-containing degradable polymers are synthesized. Further systematic investigations on these degradable polymeric chain extenders for polylactic acid are carried out, which enable polylactic acid with improved viscosity and modulus properties. This work therefore expands the molecular design of degradable polymeric chain extender and the application fields of degradable polymers via rROP, which might cause inspirations to the fields of polymer chemistry, processing and engineering.

Synthesis and self-assembly of poly(4-vinylphenol)-b-poly(vinyl alcohol) diblock copolymer for invertible core-shell nanoparticles

We report the synthesis of the amphiphilic diblock copolymer, poly (vinyl phenol)-block-poly (vinyl alcohol), and its reversible formation of invertible core-shell nanoparticles. The diblock copolymer composed of poly (4-vinylphenol) (P4VPh) and poly (vinyl alcohol) (PVA) was prepared by the switchable reversible addition-fragmentation chain transfer polymerization (switchable-RAFT) of 4-acetoxystyrene and vinyl acetate and subsequent acetyl deprotection. The diblock copolymer was soluble in dimethyl sulfoxide (DMSO) but self-assembled into core-shell nanoparticles with the addition of H2O or tetrahydrofuran (THF). The formation and transition of the invertible core-shell system in response to solvent composition was characterized by 1H NMR, dynamic light scattering, and transmission electron microscopy. Interestingly, the fluorescent behavior of the P4VPh block was changed according to the morphological change of core-shell nanoparticle induced by solvent composition. With increasing the H2O content, the P4VPh chains in the DMSO solution collapsed and the diblock copolymers self-assembled to core-shell type micelles. Aggregation of P4VPh chains increased the local concentration of the phenolic group, resulting in fluorescence quenching. However, with the addition of THF to the DMSO solution, the inverted core-shell nanoparticles were formed where segregated P4VPh chains showed fluorescence.

Controlled switching thiocarbonylthio end-groups enables interconvertible radical and cationic single-unit monomer insertions and RAFT polymerizations

To emulate the ordered arrangement of monomer units found in natural macromolecules, single-unit monomer insertion (SUMI) have emerged as a potent technique for synthesizing sequence-controlled vinyl polymers. Specifically, numerous applications necessitate vinyl polymers encompassing both radically and cationically polymerizable monomers, posing a formidable challenge due to the distinct thiocarbonylthio end-groups required for efficient control over radical and cationic SUMIs. Herein, we present a breakthrough in the form of interconvertible radical and cationic SUMIs achieved through the manipulation of thiocarbonylthio end-groups. The transition from a trithiocarbonate (for radical SUMI) to a dithiocarbamate (for cationic SUMI) is successfully accomplished via a radical-promoted reaction with bis(thiocarbonyl) disulfide. Conversely, the reverse transformation utilizes the reaction between dithiocarbamate and bistrithiocarbonate disulfide under a cationic mechanism. Employing this strategy, we demonstrate a series of synthetic examples featuring discrete oligomers containing acrylate, maleimide, vinyl ether, and styrene, compositions unattainable through the SUMI of a single mechanism alone.

Thermal Solution Depolymerization of RAFT Telechelic Polymers.

Thermal solution depolymerization is a promising low-temperature chemical recycling strategy enabling high monomer recovery from polymers made by controlled radical polymerization. However, current methodologies predominantly focus on the depolymerization of monofunctional polymers, limiting the material scope and depolymerization pathways. Herein, we report the depolymerization of telechelic polymers synthesized by RAFT polymerization. Notably, we observed a significant decrease in the molecular weight (Mn) of the polymers during monomer recovery, which contrasts the minimal Mn shift observed during the depolymerization of monofunctional polymers. Introducing Z groups at the center or both ends of the polymer resulted in distinct kinetic profiles, indicating partial depolymerization of the bifunctional polymers, as supported by mathematical modeling. Remarkably, telechelic polymers featuring R-terminal groups showed up to 68% improvement in overall depolymerization conversion compared to their monofunctional analogues, highlighting the potential of these materials in chemical recycling and the circular economy.

Trace organic–inorganic hybrid lead halide perovskite nanocrystals as photocatalysts for PET-RAFT polymerization with high efficiency

Lead halide perovskite has emerged as a new class of materials in photocatalysis due to its promising photocatalytic performance. Here, we introduce organic–inorganic hybrid lead halide perovskite (OIHP) nanocrystals as photocatalysts (PCs) for efficient photoinduced electron/energy transfer–reversible addition–fragmentation chain transfer (PET-RAFT) polymerization. PET-RAFT polymerization is successfully conducted with 0.025 wt% PC loading under blue light (6 mW/cm2, 460 nm), yielding upwards of 90 % monomer conversion and polymer products with narrow dispersity (≤1.20) within 2 h, demonstrating a fast polymerization rate. Moreover, the oxygen resistance of the polymerization process has been demonstrated. Due to the advantages of low PC usage, fast polymerization rate and oxygen tolerance, OIHP mediated PET-RAFT polymerization is expected to be used for large-scale production and industrial applications.

Highly efficient removal of amine via ion bonds based on renewable graphene templated poly-acids generated via reversible addition-fragmentation chain transfer polymerizations

As the only alkaline gas in the atmosphere, ammonia (NH3) is a promoter of atmospheric haze generation. It is also one of the main indoor air pollutants, and has an irritating and corrosive effect on the upper respiratory tract of the human body. Here, we report the synthesis of polymer composites with reduced graphene oxide (rGO) as template for the efficient removal of ammonia via ion bonds under ambient conditions. rGO has an ultra-large specific surface area for immobilizing pyrene-terminated poly-acids (PyPAA and PyPSSA) to obtain polymer/rGO composites (PyPAA/rGO and PyPSSA/rGO) which are cross-linked by calcium alginate (CA) to form a three-dimensional highly porous spherical aerogel (polymer/rGO/CA) platelet. Reversible addition-fragmentation chain transfer (RAFT) polymerization is used to synthesize two poly-acids with acidic groups, which can react with NH3 to form ammonium salts via ionic bonding, resulting in the chemical removal of NH3 without the generation of any other by-products. Impressively, 100 mg of PyPAA/rGO and PyPSSA/rGO composites could remove 18.7 mg and 12 mg of NH3, respectively. The current methodology to prepare poly-acids/rGO composites provides a means for efficient removal of NH3 pollutant.

Cellulose nanocrystal thermal smart molecular brushes with upper critical aggregation temperature

Grafting thermo-responsive polymers onto cellulose nanocrystals (CNCs) and achieving critical temperature regulation has drawn significant research interest. The thermal transition behavior of CNCs can be controlled by adjusting the polymer molecular brushes on the CNCs surface. We synthesized poly((2-dimethylamino) ethyl methacrylate) (PDMAEMA) grafted CNCs via surface-initiated reversible addition–fragmentation chain transfer, followed by modifying PDMAEMA brushes into poly-3-dimethyl(methacryloyloxyethyl) ammonium propane sulfonate (PDMAPS) brushes via quaternization. The critical temperature was regulated by modifying and grafting of poly (ethylene glycol) methacrylate. Found the thermal stimulus-responsive type and transition point of CNCs can be controlled by adjusting the surface molecular brushes. Ultraviolet-visible spectroscopy and dynamic light scattering analyses indicated that CNC–PDMAEMA aggregated above 70 °C, whereas CNC–PDMAPS aggregated below 31 °C. The thermo-responsive materials based on CNCs exhibited a conversion from a lower critical aggregation temperature to an upper critical aggregation temperature (UCAT) type. CNC–PDMAPS–mPEG was obtained by modifying and grafting for UCAT to be regulated to approximately 37 °C, which is close to the human body temperature. CNC–PDMAPS and CNC–PDMAPS–mPEG exhibited only microscopic alterations and could encapsulate and release substances. Therefore, they demonstrate considerable potential for biomedical applications.

Block Copolymer Self-assembly: Exploitation of Hydrogen Bonding for Nanoparticle Morphology Control via Incorporation of Triazine Based Comonomers by RAFT Polymerization.

Synthesis of polymeric nanoparticles of controlled non-spherical morphology is of profound interest for a wide variety of potential applications. Self-assembly of amphiphilic diblock copolymers is an attractive bottom-up approach to prepare such nanoparticles. In the present work, RAFT polymerization is employed to synthesize a variety of poly(N,N-dimethylacrylamide)-b-poly[butyl acrylate-stat-GCB] copolymers, where GCB represents vinyl monomer containing triazine based Janus guanine-cytosine nucleobase motifs featuring multiple hydrogen bonding arrays. Hydrogen bonding between the hydrophobic blocks exert significant influence on the morphology of the resulting nanoparticles self-assembled in water. The Janus feature of the GCB moieties makes it possible to use a single polymer type in self-assembly, unlike previous work exploiting, e.g., thymine-containing polymer and adenine-containing polymer. Moreover, the strength of the hydrogen bonding interactions enables use of a low molar fraction of GCB units, thereby rendering it possible to use the present approach for copolymers based on common vinyl monomers for the development of advanced nanomaterials.

β-Triketones as Reactive Handles for Polymer Diversification via Dynamic Catalyst-Free Diketoenamine Click Chemistry.

The spontaneous condensation of amines with β-triketones (TK), forming β,β'-diketoenamines (DKE) and releasing water as the sole byproduct, exhibits many of the hallmarks of "click" reactions. Such characteristics render TKs as a highly advantageous platform for efficient polymer diversification, even in biological contexts. Leveraging reversible addition-fragmentation chain transfer (RAFT) and photoiniferter polymerization of novel TK-containing vinylic monomers, we synthesized polymers containing pendent TKs with excellent control of molecular weights, even in excess of 106 g mol-1. Under mild, catalyst-free conditions, poly(β-triketone methacrylate) could be modified with a diverse scope of amines containing a plethora of functional groups. The high efficiency of this functionalization approach was further emphasized when grafting-to with poly(ethylene glycol)-amine resulting in bottlebrushes with molecular weights reaching 2.0 × 107 g mol-1. Critically, while the formed DKE linkages are stable under ambient conditions, they undergo catalyst-free, dynamic transamination at elevated temperatures, paving the way for associative covalent adaptable networks. Overall, we introduce pendent triketone moieties into methacrylate and acrylamide polymers, establishing a novel postpolymerization modification technique that facilitates catalyst-free ligation of amines under highly permissible conditions.

Hybrid Bonding Bottlebrush Polymers Grafted from a Supramolecular Polymer Backbone.

Bottlebrush polymers, macromolecules consisting of dense polymer side chains grafted from a central polymer backbone, have unique properties resulting from this well-defined molecular architecture. With the advent of controlled radical polymerization techniques, access to these architectures has become more readily available. However, synthetic challenges remain, including the need for intermediate purification, the use of toxic solvents, and challenges with achieving long bottlebrush architectures due to backbone entanglements. Herein, we report hybrid bonding bottlebrush polymers (systems integrating covalent and noncovalent bonding of structural units) consisting of poly(sodium 4-styrenesulfonate) (p(NaSS)) brushes grafted from a peptide amphiphile (PA) supramolecular polymer backbone. This was achieved using photoinitiated electron/energy transfer-reversible addition-fragmentation chain transfer (PET-RAFT) polymerization in water. The structure of the hybrid bonding bottlebrush architecture was characterized using cryogenic transmission electron microscopy, and its properties were probed using rheological measurements. We observed that hybrid bonding bottlebrush polymers were able to organize into block architectures containing domains with high brush grafting density and others with no observable brushes. This finding is possibly a result of dynamic behavior unique to supramolecular polymer backbones, enabling molecular exchange or translational diffusion of monomers along the length of the assemblies. The hybrid bottlebrush polymers exhibited higher solution viscosity at moderate shear, protected supramolecular polymer backbones from disassembly at high shear, and supported self-healing capabilities, depending on grafting densities. Our results demonstrate an opportunity for novel properties in easily synthesized bottlebrush polymer architectures built with supramolecular polymers that might be useful in biomedical applications or for aqueous lubrication.

Sulfobetaine Zwitterions with Embedded Fluorocarbons: Synthesis and Interfacial Properties.

We describe the preparation of a new set of fluorinated sulfobetaine (FSB) zwitterionic polymers in which fluorocarbon moieties are attached directly to the zwitterionic components. An efficient two-step modification to the conventional sulfobetaine methacrylate monomer synthesis gave access to a series of polymer zwitterions containing varying extents of fluorocarbon character. FSB methacrylates proved amenable to homo- and copolymerizations using reversible addition-fragmentation chain transfer (RAFT) conditions, affording polymers with molecular weights ranging from 5 to 20 kDa and with low molecular weight distributions. Thin films of FSB homopolymers on glass proved stable to aqueous environments and exhibited increasing hydrophobicity with fluorocarbon content, as well as remarkably large water contact angle hysteresis values that enable pinning of water droplets on hydrophobic surfaces, reminiscent of the "petal effect" found in nature. FSB-containing copolymers in aqueous media demonstrated markedly reduced oil-water interfacial tension values, even with moderate (20-50 mol %) FSB incorporation.

Amphiphilic block copolymers of poly(vinylidene fluoride) and poly(ethylene glycol)

AbstractAmphiphilic block copolymers of poly(ethylene glycol) (PEG) and poly(vinylidene fluoride) (PVDF) were successfully synthesized by growing poly(vinylidene fluoride) on PEG‐chain transfer agent (PEG‐macro‐CTA) using reversible addition–fragmentation chain transfer (RAFT) polymerization. MeO‐PEG‐XA, and XA‐PEG‐XA macro‐CTAs (XA refers to the xanthate moiety), synthesized by esterification of MeO‐PEG‐OH (20,000 g mol−1) and HO‐PEG‐OH (20,000 g mol−1) with 2‐bromopropionyl bromide followed by reaction with potassium ethyl xanthate, were used to synthesize MeO‐PEG‐b‐PVDF and PVDF‐b‐PEG‐b‐PVDF, respectively. The synthesized macro‐CTAs and block copolymers were characterized by NMR (1H, 13C and 19F), FTIR, and SEC. Furthermore, the PVDF/PEG block copolymer formation was proved by 1H DOSY NMR. The thermal properties were determined by TGA and DSC. The crystallinity and electroactive phases were revealed by XRD and FTIR. The size and shape of self‐assembled block copolymers in DMF/water mixtures were determined by DLS, TEM and critical micelle concentration with fluorescence spectroscopy. The influence of molecular weight and PVDF content on the properties of copolymers is discussed.

Mucin-Inspired Polymeric Fibers for Herpes Simplex Virus Type 1 Inhibition.

Mucus lines the epithelial cells at the biological interface and is the first line of defense against multiple viral infections. Mucins, the gel-forming components of mucus, are high molecular weight glycoproteins and crucial for preventing infections by binding pathogens. Consequently, mimicking mucins is a promising strategy for new synthetic virus inhibitors. In this work, synthetic mucin-inspired polymers (MIPs) as potential inhibitors of herpes simplex virus 1 (HSV-1) are investigated. By using a telechelic reversible addition-fragmentation chain-transfer (RAFT) polymerization technique, a new dendronized polysulfatep(G1AAm-OSO3)PDSwith an amide-backbone similar to the native mucin glycoproteins is synthesized.p(G1AAm-OSO3)PDSshows mucin-like elongated fiber structure, as revealed in cryo-electron microscopy (cryo-EM) imaging, and its HSV-1 inhibition activity together with its previously reported methacrylate analoguep(G1MA-OSO3)PDS is tested. Both of the sulfated MIPs show strong HSV-1 inhibition in plaque reduction assays with IC50 values in lower nanomolar range (<3× 10-9 m) and demonstrate a high cell compatibility (CC50>1.0mgmL-1) with lower anticoagulant activity than heparin. In addition, the prophylactic and therapeutic activity of both MIPs is assessed in pre- and post-infection inhibition assays and clearly visualize their high potential for application using fluorescent microscopy imaging of infected cells.

BaTiO3 Catalyzed Ultrasonic-Driven Piezoelectric-Induced Reversible Addition-Fragmentation Chain-Transfer Polymerization in Aqueous Media.

Compared with normal stimulus such as light and heat, ultrasonic possesses much deeper penetration into tissues and organs and has lower scattering in heterogeneous systems as a noninvasive stimulus. Reversible addition-fragmentation chain-transfer polymerization (RAFT) in aqueous media is performed in a commercial ultrasonic wash bath with 40kHz frequency ultrasonic, in the presence of piezoelectric tetragonal BaTiO3 (BTO) nanoparticles. Owing to the electron transfer from BTO under the ultrasonic action, the water can be decomposed to produce hydroxyl radical (HO•) and initiate the RAFT polymerization (piezo-RAFT). The piezo-RAFT polymerization exhibits features of controllable and livingness, such as linear increase of molar mass and narrow molar mass distributions (Mw/Mn < 1.20). Excellent temporal control of the polymerization and the chain fidelity of polymers are illustrated by "ON and OFF" experiment and chain extension, separately. Moreover, this ultrasonic-driven piezoelectric-induced RAFT polymerization in aqueous media can be directly used for the preparation of piezoelectric hydrogel which have potential application for stress sensor.

Enhancing photothermal depolymerization with metalloporphyrin catalyst

AbstractThe ability to revert polymers to their original monomers represents a crucial chemical recycling technique, promoting sustainability and offering the chance to convert used materials into valuable products. In recent years, numerous studies have explored the use of polymers synthesized via reversible deactivation radical polymerization (RDRP) techniques to facilitate efficient depolymerization reactions. Herein, we report the use of a photocatalyst, zinc tetraphenylporphyrin (ZnTPP), along with light irradiation to accelerate depolymerization of polymers prepared by reversible addition‐fragmentation chain transfer (RAFT) polymerization. We explore various parameters affecting depolymerization efficiency, including solvents, reaction temperature (80, 100, and 120°C), the presence of photocatalysts (ZnTPP and Eosin Y), and the type of RAFT end‐groups, namely trithiocarbonate, dithiobenzoate, and 1H‐pyrazole‐1‐carbodithioate. For instance, when PMMA was diluted to 25 mM in 1,4‐dioxane and heated to 120°C under green light irradiation in the presence of ZnTPP (200 ppm), rapid depolymerization exceeding 70% occurred within 1 h. Without ZnTPP, under similar conditions, the reaction required over 8 h to achieve a slightly lower yield. Furthermore, this method confers moderate oxygen tolerance to the system, enabling depolymerization to proceed without the need of deoxygenation, albeit at a lower rate and consequently lesser monomer recovery (31%).

Hybrid Nanoparticles from Random Polyelectrolytes and Carbon Dots.

The present study concerns the preparation of hybrid nanostructures composed of carbon dots (CDs) synthesized in our lab and a double-hydrophilic poly(2-dimethylaminoethyl methacrylate-co-oligo(ethylene glycol) methyl ether methacrylate) (P(DMAEMA-co-OEGMA)) random copolymer through electrostatic interactions between the negatively charged CDs and the positively charged DMAEMA segments of the copolymer. The synthesis of P(DMAEMA-co-OEGMA) copolymer was conducted through RAFT polymerization. Furthermore, the copolymer was converted into a strong cationic random polyelectrolyte through quaternization of the amine groups of DMAEMA segments with methyl iodide (CH3I), and it was subsequently utilized for the complexation with the carbon dots. The molecular, physicochemical, and photophysical characterization of the aqueous solution of the copolymers and their hybrid nanoparticles was conducted using dynamic and electrophoretic light scattering (DLS, ELS) and spectroscopic techniques, such as UV-Vis, fluorescence (FS), and FT-IR spectroscopy. In addition, studies of their aqueous solution using DLS and ELS showed their responsiveness to external stimuli (pH, temperature, ionic strength). Finally, the interaction of selected hybrid nanoparticles with iron (III) ions was confirmed through FS spectroscopy, demonstrating their potential application for heavy metal ions sensing.

Introducing Targeting Units or pH-Releasable Immunodrugs into Core-Clickable Nanogels

The development of nano-sized carrier systems plays a fundamental role in immunodrug delivery and the treatment of cancer. Especially functional materials, coupled with a stimuli-responsive drug release, control the selective delivery of small molecular drugs to the target site and avoid systemic side effects. Based on this, we introduce a DBCO core-functionalized nanogel platform for pH-reversible conjugation of highly potent TLR7/8-activating imidazoquinolines and the selective targeting of macrophage mannose receptor (MMR/ CD206) expressed by immunosuppressive macrophages. DBCO-PEG4-amine functionalized polymethacrylates are synthesized by controlled RAFT polymerization and self-assembled into precursor micelles in polar aprotic solvents. Corresponding nanogels are generated via reactive ester chemistry, while conjugated DBCO–units are incorporated into the core, still accessible for click reaction with azide-functionalized structures. Regarding the preparation of targeted nanogels, trimannose equipped with azide moieties can be conjugated to the DBCO nanogels, revealing the efficient targeting of macrophages’ mannose receptor in vitro. Moreover, the broad applicability of the DBCO nanogel is demonstrated by the synthesis of an azide–containing 2-propionic-3-methylmaleic anhydride-based linker sensitive for the pH–reversible conjugation of secondary amine-modified immune modulators, such as IMDQ-Me. Via bioorthogonal DBCO click reaction, the immune modulator can reversibly be conjugated, affording pH-responsive drug-loaded nanogels that conserve the desired immune stimulatory effect in vitro. Overall, these findings highlight the potential of core–functionalized DBCO nanogels, a promising carrier system for pH–sensitive conjugated immunodrugs as well as an attractive platform for controlled targeting of MMR. Altogether, the versatile application of core-functionalized DBCO nanogels may pave the way for enhancing bioorthogonal multifunctionality inside nanocarrier systems that assist in addressing multiple targets in cancer immunotherapy.

One-pot Formulation of Cationic Oligochitosan Coated Nanoparticles via Photo- Polymerization Induced Self-Assembly.

During last few decades, oligochitosan (OCS)-coated nanoparticles have received great interest for nanomedicine, food and environment applications. However, their current formulation techniques are time-consuming with multi-synthesis/purification steps and sometimes require the use of organic solvents, crosslinkers and surfactants. Herein, we report a facile and rapid one-pot synthesis of OCS-based nanoparticles using photo-initiated reversible addition fragmentation chain transfer polymerization-induced self-assembly (Photo-RAFT PISA) under UV-irradiation at room temperature. To achieve this, OCS was first functionalized by a chain transfer agent (CTA) resulting in a macromolecular chain transfer agent (OCS-CTA), which will act as a reactive electrostatic/steric stabilizer. Owing to its UV-sensitivity, OCS-CTA was then used as photo-iniferter to initiate the polymerization of 2-hydroxypropyl methacrylate (HPMA) in aqueous acidic buffer, resulting in OCS-g-PHPMA amphiphilic grafted copolymers which self-assemble into nano-objects. Transmission electron microscopy and light scattering analysis reveal formation of spherical nanostructures.

Organic small molecule catalytic PET-RAFT electrochemical signal amplification strategy for miRNA-21 detection

Quantitative detection of the cancer-associated biomarker miRNA-21 is essential for the prevention and treatment of early-stage cancer patients. In the early diagnosis of cancer, due to the low concentration of miRNA in the organism, it is necessary to develop a fast, simple, highly sensitive and specific method using signal amplification techniques. Herein, a photo-induced electron/energy transfer reversible addition-fragmentation chain transfer polymerization signal amplification electrochemical biosensor was developed. Peptide nucleic acid was used as the recognition probe for miRNA-21 and the chain transfer agent (4-cyano-4-(dodecylsulfonylsulfanylthiocarbonyl)sulfonylpentanoic acid) bearing a carboxylic acid group was successfully conjugated with a phosphate group in the presence of ZrOCl2 to form the phosphate-Zr(IV)-carboxylic acid complex. Subsequently, the polymerization of the monomer (ferrocenylmethyl methacrylate) was achieved by blue light irradiation in the presence of erythrosin B (higher triple quantum yield) and triethanolamine (increases electron transfer rate). With this sophisticated signal amplification biosensing platform, low detection limit of 12.4 aM was achieved for miRNA-21. The biosensor reduces costs and simplifies experimentation while ensuring high sensitivity and selectivity. Meanwhile, the biosensor exhibits excellent anti-interference ability in serum samples and has great potential for practical applications in the early prevention of cancer.