Sensitized And Quenching Effects Of Fullerene Nanocomposites For Photoelectrochemical DNA Biosensors

Precise biochemical analysis and medical examination play a significant role in the development of human society as well as the promotion of human happiness and health index,which was particularly highlighted in the Corona Virus Disease 2019?COVID-19?very recently.Deriving from the electrochemical detection technique and integrating the photo-analysis with electrical-analysis,photoelectrochemical?PEC?biosensor is a novle and emerge bioanalytical device to explore biomolecular concentration or content information,which has acquired increasing attentions in the past few years.For a PEC biosensor,the input signal is a photo signal while the output signal is an electrical signal?photocurrent response?,i.e.,the completely different form of input signal and output signal,which intensively reduces the background,allowing its ultrahigh sensitivity and ultralow detection limit.Thanks for this,the PEC biosensor exhibits exceptional detectable behaviours that could meet the demands of practical analysis,making it an ideal candidate in addressing the limited sensitivity of yet proposed biosensor.According to the active mechanism,the variation of photocurrent responses is regared as one crucial element to affect the detection performance of the PEC biosensor,hence a greater variation of photocurrent responses is desirable for more exquisite detection performance.To achieve the goal,it is a powerful breakthrough to enhance the photocurrent intensity of the constructed PEC biosensor.Since the photo-to-current conversion efficiency of the photoelectric active material profoundly determines the magnitude of photocurrent intensity,to design and engineer the used photoelectric active materials for novel types of photoelectirc sensitized structure or quenched structure is very promising.Also,signal amplification strategy is required to convert limited number of target into large number of detectable output,which could further improve the sensitivity of the PEC biosensor.To this end,various photoelectric active materials with high photo-to-current efficiency were explored and efficient biomolecular signal amplification strategies were presented in this article,followed by building a series of new photoelectric sensitized structure and quenched structure.Impressively,the subsequently constructed PEC biosensors illustrated excellent detection performance for the target biomolecules,which is envisioned to advance the progress of biochemical analysis and medical examination in human society.The main contents include the following aspects.1.An Ultrasensitive Photoelectrochemical Biosensor Based on[Ru?dcbpy?₂dppz]²⁺/Rose Bengal Dyes Co-sensitized Fullerene for DNA DetectionThough preferable progresses have been achieved to improve the photoelectric performance of fullerene(C₆₀ NPs)by sensitized structure in PEC field,further application inevitably suffers from the inherent scarcities of heavy metal-involved quantum dots as sensitizers containing restricted sensitization effect,complex preparation and biological toxicity.In this work,a PEC biosensor based on[Ru?dcbpy?₂dppz]²⁺/Rose Bengal dyes co-sensitized C₆₀ NPs was constructed for ultrasensitive DNA?a fragment sequence of p53 gene?detection.With the merits of low toxicity and accessible operation,[Ru?dcbpy?₂dppz]²⁺/Rose Bengal dyes exhibited a further sensitization efficiency towards C₆₀ NPs.Through modifying wide band gap C₆₀ NPs with two narrower band gap dyes([Ru?dcbpy?₂dppz]²⁺and Rose Bengal)to form a cascade-type energy band structure,the photoelectric conversion of C₆₀ NPs was significantly improved and the visible light absorption was markedly promoted,leading to an exceptional photocurrent signal.Additionally,Nt.BstNB I enzyme-assisted target recycling amplification was employed to convert a limited quantity of target to numerous SiO₂NPs-labeled DNA sequences?the signal quencher?,resulting in a sharp decrement of photocurrent since a dramatic increment of steric hindrance on the modified electrode surface,which was performed to quantitatively estimate target.The proposed PEC biosensor for DNA detection possessed a wide linear range from 0.1 fmol/L to 1 nmol/L with a calculated detection limit of 37 amol/L.This work opened up an intriguing avenue for determination of various targets such as DNAs,microRNAs and proteins,and exhibited desirable application potential in the clinic researches,cancer therapies and other related subjects.2.p-n-Sensitized Heterostructure Co₃O₄/Fullerene with Highly Efficient Photoelectrochemical Performance for Ultrasensitive DNA DetectionSignificantly sensitized architectures meeting the requirements of high photoelectric conversion efficiency and promising photocurrent intensity are extremely desirable,but challenges in sensitizer development and efficiency in PEC fields remain.In this paper,the p-type metal oxide semiconductor Co₃O₄ was attached as an effective photosensitizer to n-type fullerene C₆₀ in view of appropriately matched energy band levels to form the highlighted p-n-sensitized heterostructure Co₃O₄/fullerene,with facilitated charge separation and accelerated carrier mobility.Compared with traditional p-n heterostructure,the p-n-sensitized heterostructure Co₃O₄/fullerene illustrated a wider range for light absorption with further enhanced light-harvesting capability,thereby leading to more exceptional PEC performance containing remarkably promoted photoelectric conversion efficiency and improved photocurrent intensity.Impressively,the photocurrent intensity obtained by Co₃O₄/fullerene was about sixfold higher than that of fullerene alone,and this achievement was quite favored compared to the reported works for fullerene sensitization,which could be responsible for the advancement of detection sensitivity for the subsequently constructed biosensor.Unambiguously,given the p-n-sensitized heterostructure Co₃O₄/fullerene of high PEC activity,the well-fabricated three-dimensional DNA walker applied as a target-cascade signal amplification strategy,and the Au layer employed as the specific linker between the photoactive material and the signal amplification product,a smart PEC biosensor was successfully enabled for ultrasensitive investigation of the model DNA?a fragment of the p53 gene?,showing a wide linear range of 60 to 1×10⁵ amol/L and a detection limit of 20 amol/L.This proposed PEC biosensor provided acceptable insights into the clinic analysis,disease therapies,and other relevant subjects.3.Different Behaviors between Fullerene-and Fullerenol-Based Label-Free Photoelectrochemical Sensing Platforms:A Comprehensive Study towards Versatile Development of BioanalysisUsing carbon nanomaterials?NMs?to fabricate label-free sensing platforms?LFSPs?for bioanalysis is highly desirable but remains challenges on the versatile development.In this study,zero-dimension?0D?fullerene and its derivative fullerenol were executed as PEC indicators to build two LFSPs,with quite different sensing behaviors highlighted from two elaborations:?i?different ability for discriminating single-stranded DNA?ssDNA?and double-stranded DNA?dsDNA?of fullerene and fullerenol,and?ii?different PEC quenching efficiency of gold nanoparticle?AuNP?against fullerene and fullerenol.Typically,having strong absorption towards both ssDNA and dsDNA via?-?stacking interactions,fullerene was absence of DNA screen.Interestingly,as rich hydroxyl groups functionalized fullerene,the produced fullerenol displayed acute ssDNA capture via intense hydrogen bonding but dsDNA emancipation,implying distinguished ssDNA/dsDNA discrimination.Meanwhile,AuNP led to PEC quenching efficiency of only 26%against fullerene while it caused that of impressively 85%against fullerenol through the visible light-induced electron transfer effect,thanks to more conducive driving force for electron migration existed in Au/fullerenol interface than in Au/fullerene interface.As a proof-of-concept application,fullerenol-based LFSP was implemented for the ultrasensitive and selective detection of target DNA?a fragment of p53 gene?,with more appreciative analysis performance containing a detectable liner ranged from 1 fmol/L to 100 pmol/L and a limit of detection of 0.33 fmol/L.This comprehensive work gave marvelous impetus to the versatile development of bioanalysis and stimulated researchers'enthusiastic to develop 0D NMs-based high-performance detecting systems,which further advanced the prospection of clinic diagnosis,medical therapies and beyond.