Electrochemical biosensors are characterized by rapid response, miniaturization, portability, and ease of operation. With tunable nanostructure, DNA has been comprehensively combined with electrochemical devices to design high-sensitivity and selectivity biosensors for the achievement of disease diagnosis, food safety, and environmental monitoring. In recent years, DNA-functionalized electrochemical biosensors have made significant research progress. In this article, the recent research progress of DNA-functionalized electrochemical biosensors for in vitro and in vivo disease diagnosis was reviewed. The structure and sensing principles of DNA-functionalized electrochemical biosensors were first summarized. The preparation of DNA-functionalized electrochemical biosensors based on nanomaterials was introduced in detail. Meanwhile, the latest evolution of integrated and portable DNA-functionalized electrochemical biosensors for in vitro disease diagnosis was summarized. For a further step, the construction of implantable DNA-functionalized electrochemical biosensors for in vivo and real-time disease monitoring was overviewed. Finally, the challenges and outlook of DNA-functionalized electrochemical biosensors were discussed to provide a guideline for the future development of DNA-functionalized electrochemical biosensors.

As a carrier of genetic information, DNA is a versatile module for fabricating nanostructures and nanodevices. Functional molecules could be integrated into DNA by precise base complementary pairing, greatly expanding the functions of DNA nanomaterials. These functions endow DNA nanomaterials with great potential in the application of biomedical field. In recent years, functional DNA nanomaterials have been rapidly investigated and perfected. There have been reviews that classified DNA nanomaterials from the perspective of functions, while this review primarily focuses on the preparation methods of functional DNA nanomaterials. This review comprehensively introduces the preparation methods of DNA nanomaterials with functions such as molecular recognition, nanozyme catalysis, drug delivery, and biomedical material templates. Then, the latest application progress of functional DNA nanomaterials is systematically reviewed. Finally, current challenges and future prospects for functional DNA nanomaterials are discussed.

Persistent luminescence nanoprobes (PLNPs) can remain luminescent after ceasing excitation. Due to the ultra-long decay time of persistent luminescence (PersL), autofluorescence interference can be efficiently eliminated by collecting PersL signal after autofluorescence decays completely, thus the imaging contrast and sensing sensitivity can be significantly improved. Since near-infrared (NIR) light shows reduced scattering and absorption coefficient in penetrating biological organs or tissues, near-infrared persistent luminescence nanoprobes (NIR PLNPs) possess deep tissue penetration and offer a bright prospect in the areas of in vivo biosensing/bioimaging. In this review, we firstly summarize the design of different types of NIR PLNPs for biosensing/bioimaging, such as transition metal ions-doped NIR PLNPs, lanthanide ions-doped NIR PLNPs, organic molecules-based NIR PLNPs, and semiconducting polymer self-assembled NIR PLNPs. Notably, organic molecules-based NIR PLNPs and semiconductor self-assembled NIR PLNPs, for the first time, were introduced to the review of PLNPs. Secondly, the effects of different types of charge carriers on NIR PersL and luminescence decay of NIR PLNPs are significantly emphasized so as to build up an in-depth understanding of their luminescence mechanism. It includes the regulation of valence band and conduction band of different host materials, alteration of defect types, depth and concentration changes caused by ion doping, effective radiation transitions and energy transfer generated by different luminescence centers. Given the design and potential of NIR PLNPs as long-lived luminescent materials, the current challenges and future perspective in this rapidly growing field are also discussed.

Latent fingerprints (LFPs) are highly specific to individuals, and LFP imaging has played an important role in areas such as forensic investigation and law enforcement. Presently, LFP imaging still faces considerable problems, including background interference and destructive and complex operations. Herein, we have designed a background-free, nondestructive, and easy-to-perform method for LFP imaging based on pH-mediated recognition of LFPs by carboxyl group-functionalized Zn₂GeO₄: Mn (ZGO: Mn-COOH) persistent luminescence nanorods (PLNRs). By simply adjusting the pH of the ZGO: Mn-COOH colloid dispersion to a certain acidic range, the negatively charged ZGO: Mn-COOH readily binds to protonated fingerprint ridges via electrostatic attraction. The ZGO: Mn-COOH colloid dispersion can be stored in portable commercial spray bottles, and the LFPs have been easily detected in situ by simply dropping the colloid dispersion on the LFPs. Moreover, since the ZGO: Mn-COOH can remain luminescent after excitation ceases, background color and background fluorescence interference were efficiently removed by simply capturing the luminescent LFP images after the excitation ceased. The entire LFP imaging process can be easily conducted without any destructive or complex operations. Due to the great versatility of the developed method for LFP imaging, clear LFP images with well-resolved ridge patterns were obtained. The designed background-free, nondestructive, and easy-to-perform LFP imaging strategy has great potential for future applications, such as forensic investigations and law enforcement.

Owing to their unique pattern and abundant chemical composition, latent fingerprints (LFPs) can serve as "ID cards" and "information banks" of donors and therefore are valuable for forensic investigation, access control, and even medical diagnosis. LFP imaging has attracted considerable attention, and a great variety of contrast agents has been developed. In LFP imaging, background signals such as background fluorescence from the underlying surface can seriously blur the LFP images and decrease imaging sensitivity; thus, great efforts have been made to eliminate background interference. Here, we stratify the recent progress in background-free LFP imaging by making use of the difference in properties between contrast agents and background compounds. For example, near-infrared (NIR) light-activatable contrast agents can efficiently remove background signals in LFP imaging because the background compounds cannot be excited by NIR light, showing that the difference in excitation properties between contrast agents and background compounds can be employed to eliminate background interference. This review is organized around background-free LFP imaging based on the difference in optical properties between contrast agents and background compounds: (i) different excitation wavelengths, (ii) different emission wavelengths, (iii) different luminescence lifetime values, (iv) different plasmonic properties, (v) different photothermal properties, and (vi) different electrochemiluminescence properties.

Flexible and stretchable biosensors that can monitor and quantify the electrical or chemical signals generated by specific microenvironments have attracted a great deal of attention. Wearable biosensors that can be intimately attached to skin or tissue provide a new opportunity for medical diagnostics and therapy. In recent years, there has been enormous progress in device integration and the design of materials and manufacturing processes for flexible and stretchable systems. Here, we describe the most recent developments in nanomaterials employed in flexible and stretchable biosensors. We review successful examples of such biosensors used for the detection of vital physiological and biological markers such as gas released from organisms. Furthermore, we provide a detailed overview of recent achievements regarding integrated platforms that include multifunctional nanomaterials. The issues and challenges related to the effective integration of multifunctional nanomaterials in bio-electronics are also discussed.

Adsorbents are widely employed in both fundamental and applied research areas such as separation technology, biotechnology, and environmental science. Selectivity and reusability are two most important requirements for adsorbents. Aptamers exhibit perfect selectivity and easy regeneration, which make them uniquely effective adsorption materials. Herein, we have rationally designed novel aptamer-based adsorbents and investigated their performance in extraction/separation of targets from an aqueous solution. These adsorbents can selectively extract targets from complicated sample matrices containing background com­pounds. Moreover, they can also be easily recycled without a significant loss of adsorption capacity. Notably, the adsorbents did not affect the activity of isolated biological samples, revealing their potential for the purification/separation of biomolecules. Composite adsorbents were constructed using aptamer-based adsorbents and a porous polymer, displaying highly efficient target separation from aqueous solution. Finally, separation columns were constructed, and targets in the aqueous solution were efficiently separated by these columns. The aptamer- based adsorbents described here exhibit great promise for potential applications in separation technology, biotechnology, and environment-related areas.