Advanced Smart Nanomaterials with Integrated Logic-Gating and Biocomputing: Dawn of Theranostic Nanorobots

Development of gold nanoparticles-aptamer nanocomposite for multiplexed analysis of antibiotics and design of molecular logic gates

The widespread use of antibiotics caused severe problems of antibiotic residues in foodstuffs and water, posing a serious threat to public health and thus urging the development of sensitive, selective, and rapid detection methods for antibiotics. In this study, a fluorescence resonance energy transfer (FRET)-based system is developed for the multiplexed analysis of chloramphenicol (CAP) and streptomycin (Strep) with detection limits of 2.51 and 8.69μg l^-1, respectively. The FRET-based system consists of Cy3-tagged anti-CAP aptamer-conjugated gold nanoparticles (AuNPs) (referred to as AuNPs-AptCAP) and Cy5-tagged anti-Strep aptamer-conjugated AuNPs (referred to as AuNPs-AptStrep). In addition, AuNPs-AptCAP and AuNPs-AptStrep have been demonstrated to serve as signal transducers for implementing a series of logic operations such as YES, NOT, INH, OR, (2-4)-Decoder and even more complicated multi-level logic gates (OR-INH). Based on the outputs of logic operations, it could be figured out whether targeted analytes were present or not, thus enabling multiplex sensing and evaluation of pollution status. This proof of concept study might provide a new route for the enhanced sensing performance to distinguish different pollution status as well as the design of molecular mimics of logic elements to demonstrate better applicability.

Engineering chemical communication between micro/nanosystems

Chemical communication, based on the exchange of molecules as messengers, allows different entities to share information, cooperate and orchestrate collective behaviors. In recent years, the development of strategies of chemical communication between micro/nanosystems is becoming a key emergent topic in micro/nanotechnology, biomimicry and related areas. In this tutorial review, we provide a general perspective of the concepts used on the topic of chemical communication, and the advances made using different approaches that include nanomaterials, synthetic biology and information-processing tools. Although studies in this direction are very recent, they can be divided in two main categories: (i) communication between abiotic systems and (ii) communication between living and abiotic systems. Using illustrative examples, we give an overview of the ongoing progress, potential applications in different areas and current challenges. The engineering of chemical communication between micro/nanosystems represents a paradigm shift and may open a myriad of new concepts, applications and new technological possibilities in the near future in a number of research fields.

Engineering Nanorobots for Tumor-Targeting Drug Delivery: From Dynamic Control to Stimuli-Responsive Strategy

Nanotechnology has been widely applied to the fabrication of drug delivery systems in the past decades. Recently, with the progress made in microfabrication approaches, nanorobots are steadily becoming a promising means for tumor-targeting drug delivery. In general, nanorobots can be divided into two categories: nanomotors and stimuli-responsive nanorobots. Nanomotors are nanoscale systems with the ability to convert surrounding energies into mechanical motion, whereas stimuli-responsive nanorobots are featured with activatable capacity in response to various endogenous and exogenous stimulations. In this minireview, the dynamic control of nanomotors and the rational design of stimuli-responsive nanorobots are overviewed, with particular emphasis on their contribution to tumor-targeting therapy. Moreover, challenges and perspectives associated with the future development of nanorobots are presented.

Continuous response fluorescence sensor for three small molecules based on nitrogen-doped carbon quantum dots from prunus lannesiana and their logic gate operation

In this study, an environmentally friendly and water-soluble nitrogen-doped carbon quantum dots (N-CQDs) with quantum yield (QY) of 8.59% were prepared by one-step hydrothermal synthesis without any chemical reagent using the leaves of prunus lannesiana as precursors. The properties and quality of N-CQDs were investigated by Ultraviolet-visible absorption spectroscopy, infrared spectroscopy, X-ray photoelectron spectroscopy, zeta potential, high-resolution transmission electron microscopy and fluorescence spectroscopy. The fluorescence of the prepared N-CQDs can be quenched by Fe³⁺ through the synergistic effect of the formation of non-fluorescent complex and internal filtration effect (IFE) between Fe³⁺ and N-CQDs. And the quenched fluorescence can be "turned on" after adding ascorbic acid (AA) because Fe³⁺ can be released from the surface of N-CQDs through the redox reaction between AA and Fe³⁺. While the restored fluorescence can be "turned off" again by hydrogen peroxide (H₂O₂) due to the re-oxidation of Fe²⁺ to Fe³⁺. So, the three inputs "logic gate" is achieved and the "on-off-on-off" continuous response fluorescence sensor is formed, which can be applied for the continuous detection of Fe³⁺, AA and H₂O₂ with the linear range of 40-260 μM, 10-200 μM and 40-140 μM, respectively. Finally, the sensor was successfully applied to determine Fe³⁺, AA and H₂O₂ in real samples with the satisfactory recoveries (95.35%-104.10%) and repeatability (relative standard deviation (RSD) ≤ 1.68%). The continuous response fluorescence sensor prepared by simple green synthesis route has the characteristics of fast response, acceptable sensitivity and good selectivity.

pH-responsive black phosphorus quantum dots for tumor-targeted photodynamic therapy

Black phosphorus quantum dots(BPQDs) have shown a good application prospect in the field of tumor therapy due to their photoelectric effect and good biodegradability. Due to the active endocytosis and fast metabolic efficiency of tumor cells, BPQDs are easy to be absorbed by tumor cells. However, this does not guarantee that BPQDs will be completely targeted to tumor cells, and normal cells will also absorb BPQDs. Because the cell membrane is negatively charged, BPQDs are also negatively charged and are not easily absorbed by cells under the action of electrostatic repulsion. Surface pegylation is the most common modification method of black phosphorus at present. However, surface pegylation can reduce the uptake of BPQDs by tumor cells. Positive PEG is also easy to be recognized and swallowed by the reticuloendothelial system. The inherent instability and poor tumor targeting of BPQDs under physiological conditions limit further research and clinical application. For this purpose, we selected cationic polymer polyethylenimine (PEI) to modify BPQDs and then added RGD peptides targeting tumor cells. An outer layer of negatively charged PEG+DMMA makes the nanosystem more stable . In the acidic environment of the tumor, the PEG layer has a charge reversal, and the positively charged PEI and the RGD polypeptide BPQDs targeted by the tumor cells are released into the tumor cells. It provides a new method for efficiently and accurately transporting BPQDs, a novel photosensitive nanomaterial, into tumor cells for photodynamic therapy.

The Construction of DNA Logic Gates Restricted to Certain Live Cells Based on the Structure Programmability and Aptamer-Cell Affinity of G-Quadruplexes

DNA computation is considered a fascinating alternative to silicon-based computers; it has evoked substantial attention and made rapid advances. Besides realizing versatile functions, implementing spatiotemporal control of logic operations, especially at the cellular level, is also of great significance to the development of DNA computation. However, developing simple and efficient methods to restrict DNA logic gates performing in live cells is still a challenge. In this work, a series of DNA logic gates was designed by taking full advantage of the diversity and programmability of the G-quadruplex (G4) structure. More importantly, by further using the high affinity and specific endocytosis of cells to aptamer G4, an INHIBIT logic gate has been realized whose operational site is precisely restricted to specific live cells. The design strategy might have great potential in the field of molecular computation and smart bio-applications.

Wavelength-Selective Activation of Photocaged DNAzymes for Metal Ion Sensing in Live Cells

RNA-cleaving DNAzymes are widely applied as sensors for detecting metal ions in environmental samples owing to their high sensitivity and selectivity, but their use for sensing biological metal ions in live cells is challenging because constitutive sensors fail to report the spatiotemporal heterogeneity of biological processes. Photocaged DNAzymes can be activated by light for sensing purposes that need spatial and temporal resolution. Studying complex biological processes requires logic photocontrol, but unfortunately all the literature-reported photocaged DNAzymes working in live cells cannot be selectively controlled by light irradiation at different wavelengths. In this work, we developed photocaged DNAzymes responsive to UV and visible light using a general synthetic method based on phosphorothioate chemistry. Taking the Zn²⁺-dependent DNAzyme sensor as a model, we achieved wavelength-selective activation of photocaged DNAzymes in live human cells by UV and visible light, laying the groundwork for the logic activation of DNAzyme-based sensors in biological systems.

Nonviral Locally Injected Magnetic Vectors for In Vivo Gene Delivery: A Review of Studies on Magnetofection

Magnetic nanoparticles have been widely used in nanobiomedicine for diagnostics and the treatment of diseases, and as carriers for various drugs. The unique magnetic properties of "magnetic" drugs allow their delivery in a targeted tumor or tissue upon application of a magnetic field. The approach of combining magnetic drug targeting and gene delivery is called magnetofection, and it is very promising. This method is simple and efficient for the delivery of genetic material to cells using magnetic nanoparticles controlled by an external magnetic field. However, magnetofection in vivo has been studied insufficiently both for local and systemic routes of magnetic vector injection, and the relevant data available in the literature are often merely descriptive and contradictory. In this review, we collected and systematized the data on the efficiency of the local injections of magnetic nanoparticles that carry genetic information upon application of external magnetic fields. We also investigated the efficiency of magnetofection in vivo, depending on the structure and coverage of magnetic vectors. The perspectives of the development of the method were also considered.

Rapid and Easy-to-Use Method for Accurate Characterization of Target Binding and Kinetics of Magnetic Particle Bioconjugates for Biosensing

The ever-increasing use of magnetic particle bioconjugates (MPB) in biosensors calls for methods of comprehensive characterization of their interaction with targets. Label-free optical sensors commonly used for studying inter-molecular interactions have limited potential for MPB because of their large size and multi-component non-transparent structure. We present an easy-to-use method that requires only three 20-min express measurements to determine the key parameters for selection of optimal MPB for a biosensor: kinetic and equilibrium characteristics, and a fraction of biomolecules on the MPB surface that are capable of active targeting. The method also provides a prognostic dependence of MPB targeting efficiency upon interaction duration and sample volume. These features are possible due to joining a magnetic lateral flow assay, a highly sensitive sensor for MPB detection by the magnetic particle quantification technique, and a novel mathematical model that explicitly describes the MPB-target interactions and does not comprise parameters to be fitted additionally. The method was demonstrated by experiments on MPB targeting of cardiac troponin I and staphylococcal enterotoxin B. The validation by an independent label-free technique of spectral-correlation interferometry showed good correlation between the results obtained by both methods. The presented method can be applied to other targets for faster development and selection of MPB for affinity sensors, analytical technologies, and realization of novel concepts of MPB-based biosensing in vivo.

Binding of chloroaurate to polytyrosine-PEG micelles leads to an anti-Turkevich pattern of reduction

Here we report formation of gold nanoparticles (GNPs) in micelles of polytyrosine-PEG copolymers that combine the properties of a reducer and a stabilizer. The size and properties of the GNPs were tailored by the excess chloroaurate over the copolymer. The latter quickly formed non-covalent complexes with HAuCl4 and then slowly reduced it to form GNPs. 3 Tyr residues are consumed by reduction of one mole of chloroaurate. The size of the GNPs was controlled by the [Tyr]/[Au(iii)] molar ratio. Small GNPs with D ≅ 8 nm were formed at [Tyr]/[Au(iii)] = 0.5-1.5. 90% of these small GNPs remained bound to the copolymer and could be stored in a lyophilized state. Such polypeptide-gold hybrid materials produced at [Tyr]/[Au(iii)] = 0.5 demonstrated high activity in the catalytic reduction of 4-nitrophenol by sodium borohydride. [Tyr]/[Au(iii)] = 5 led to the formation of large nanoplates (D ≅ 30-60 nm). Thus, in the polymer-based system the GNP size grew in line with the excess of the reducing agent in contrast to Turkevich synthesis of GNPs with citric acid, which also combines the functions of a stabilizer and a reducer. The difference results from the reduction of HAuCl4 in solution according to the Turkevich method and in the micelles of the amphiphilic polymer where the seed growth is limited by the amount of neighboring reducer.

Scalable Logic Circuits with Multiple Outputs and an Automatic Reset Function Based on DNAzyme-Mediated Branch Migration

A scalable logic platform made up of multilayer DNA circuits was constructed using Pb²⁺, Cu²⁺, and Zn²⁺ as the three inputs and three different fluorescent signals as the outputs. DNAzyme-guided cyclic cleavage reactions and DNA toehold-mediated strand branch migration were utilized to organize and connect nucleic acid probes for building the high-level logic architecture. The sequence communications between each circuit enable the logic network to work as a keypad lock, which is an information protection model at the molecular level. The multi-output mode was used to monitor the gradual unlocking process of the security system, from which one can determine which password is correct or not immediately. The autocatalytic cleavage of DNAzyme makes the biocomputing circuit feasible to realize the reset function automatically without external stimuli. Importantly, the logic platform is robust and can work effectively even in complex environmental samples.

In vivo blockade of mononuclear phagocyte system with solid nanoparticles: Efficiency and affecting factors

Smart nanomaterials, contrast nanoparticles and drug nanocarriers of advanced targeting architecture were designed for various biomedical applications. Most of such agents demonstrate poor pharmacokinetics in vivo due to rapid elimination from the bloodstream by cells of the mononuclear phagocyte system (MPS). One of the promising methods to prolong blood circulation of the nanoparticles without their modification is MPS blockade. The method temporarily decreases macrophage endocytosis in response to uptake of a low-toxic non-functional material. The effect of different factors on the efficiency of macrophage blockade in vivo induced by solid nanomaterials has been studied here. Those include: blocker nanoparticle size, ζ-potential, surface coating, dose, mice strain, presence of tumor or inflammation. We found that the blocker particle coating type had the strongest effect on MPS blockade efficiency, which allowed to prolong functional particle blood circulation half-life 18 times. The mechanisms capable of regulation of the MPS blockade have been demonstrated, which can promote application of this phenomenon in medicine for improving delivery of diagnostic and therapeutic nanomaterials.

The prototypes of nanozyme-based nanorobots

Artificial nanorobot is a type of robots designed for executing complex tasks at nanoscale. The nanorobot system is typically consisted of four systems, including logic control, driving, sensing and functioning. Considering the subtle structure and complex functionality of nanorobot, the manufacture of nanorobots requires designable, controllable and multi-functional nanomaterials. Here, we propose that nanozyme is a promising candidate for fabricating nanorobots due to its unique properties, including flexible designs, controllable enzyme-like activities, and nano-sized physicochemical characters. Nanozymes may participate in one system or even combine several systems of nanorobots. In this review, we summarize the advances on nanozyme-based systems for fabricating nanorobots, and prospect the future directions of nanozyme for constructing nanorobots. We hope that the unique properties of nanozymes will provide novel ideas for designing and fabricating nanorobotics.

Logic Gates Based on DNA Aptamers

DNA bio-computing is an emerging trend in modern science that is based on interactions among biomolecules. Special types of DNAs are aptamers that are capable of selectively forming complexes with target compounds. This review is devoted to a discussion of logic gates based on aptamers for the purposes of medicine and analytical chemistry. The review considers different approaches to the creation of logic gates and identifies the general algorithms of their creation, as well as describes the methods of obtaining an output signal which can be divided into optical and electrochemical. Aptameric logic gates based on DNA origami and DNA nanorobots are also shown. The information presented in this article can be useful when creating new logic gates using existing aptamers and aptamers that will be selected in the future.

Hepatoprotective Angelica sinensis silver nanoformulation against multidrug resistant bacteria and the integration of a multicomponent logic gate system

The rampant usage of antibiotics has led to the emergence of toxicity, especially hepatotoxicity and the emergence of microbial drug resistance. Hence, a series of novel hepatoprotective, biocompatible, antibacterial silver nanoformulations (AS-AgNPs) were developed by using the important Chinese medicinal plant Angelica sinensis. The different size of AS-AgNPs were characterized by UV-Visible spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). The size-dependent antibacterial properties of AS-AgNPs were investigated against Gram-positive, Gram-negative and multi-drug resistant bacteria. The minimum inhibitory concentration (MIC) of AS-AgNPs with different size against six bacteria was found to be in the range of 5-100 μg mL-1 with no resistance till 12 cycles. TEM and SEM results of bacteria after the treatment suggested that AS-AgNPs disrupted the cell membrane by creating pores. The cytocompatibility and cytoprotective effect of AS-AgNPs were evaluated against HepG2 cell lines, which showed that 85% of cells were viable up to 100 μg mL-1 of the concentration with almost no change in AST and ALT levels. Further, a logic combinatorial library, including basic logic gates (AND, OR, NOR, INHIBIT, IMPLICATION, and YES), three input logic gates (OR, and NOR) and combinatorial gates (INH-OR, INH-YES, INH-INH, AND-NOR, and NOT-AND-NOR) were designed by integrating multi-components based on the interaction between AS-AgNP1 and bacteria, where DiSC3(5) was used as the signal reporter. This system clearly demonstrates the ability of simple logic circuits to perform sophisticated analysis for the detection of multiple bacteria.

Cancer diagnosis with DNA molecular computation

Early and precise cancer diagnosis substantially improves patient survival. Recent work has revealed that the levels of multiple microRNAs in serum are informative as biomarkers for the diagnosis of cancers. Here, we designed a DNA molecular computation platform for the analysis of miRNA profiles in clinical serum samples. A computational classifier is first trained in silico using miRNA profiles from The Cancer Genome Atlas. This is followed by a computationally powerful but simple molecular implementation scheme using DNA, as well as an effective in situ amplification and transformation method for miRNA enrichment in serum without perturbing the original variety and quantity information. We successfully achieved rapid and accurate cancer diagnosis using clinical serum samples from 22 healthy people (8) and people with lung cancer (14) with an accuracy of 86.4%. We envision that this DNA computational platform will inspire more clinical applications towards inexpensive, non-invasive and rapid disease screening, classification and progress monitoring.

A 1-to-2 demultiplexer hybrid nanocarrier for cargo delivery and activation

A biocomputing strategy implemented in hybrid nanocarriers for controlled cargo delivery is described. The nanodevice consists of enzyme-functionalized Janus Au-mesoporous silica nanoparticles, which behave as an electronic demultiplexer (DEMUX). The nanocarrier is capable of reading molecular information from the environment (lactose) and selecting one of two possible outputs (galactose production or 4-methylumbellilferone release and activation) depending on the presence of an addressing input (NAD⁺).

"Plug and Play" logic gate construction based on chemically triggered fluorescence switching of gold nanoparticles conjugated with Cy3-tagged aptamer

Gold nanoparticles (AuNPs) conjugated with Cy3-tagged aptamer which can specifically recognize chloramphenicol (CAP) (referred to as AuNPs-AptCAP) are described. CAP can trigger the configuration change of CAP binding aptamer, and thus switching the fluorescence of AuNPs-AptCAP through changing the efficiency of the fluorescence resonance energy transfer (FRET) system with Cy3 as donors and AuNPs as recipients. AuNPs-AptCAP exhibits a linear range of CAP concentrations from 26.0 to 277 μg L^-1 with a limit of detection of 8.1 μg L^-1 when Cy3 was excited at 530 nm and emission was measured at 570 nm. More importantly, AuNPs-AptCAP can be utilized as signal transducers for the build-up of a series of logic gates including YES, PASS 0, INH, NOT, PASS 1, and NAND. Utilizing the principle of a metal ion-mediated fluorescence switch together with a strong metal ion chelator, the fluorescence of AuNPs-AptCAP could be modulated by adding metal ions and EDTA sequentially. Therefore, a "Plug and Play" logic system based on AuNPs-AptCAP has been realized by simply adding other components to create new logic functions. This work highlights the advantages of simple synthesis and facile fluorescence switching properties, which will provide useful knowledge for the establishment of molecular logic systems. Graphical abstract.

Enhancement of the blood-circulation time and performance of nanomedicines via the forced clearance of erythrocytes

The rapid elimination of nanoparticles from the bloodstream by the mononuclear phagocyte system limits the activity of many nanoparticle formulations. Here, we show that inducing a slight and transient depletion of erythrocytes in mice (~5% decrease in haematocrit) by administrating a low dose (1.25 mg kg^-1) of allogeneic anti-erythrocyte antibodies increases the circulation half-life of a range of short-circulating and long-circulating nanoparticle formulations by up to 32-fold. Treatment of the animals with anti-erythrocyte antibodies significantly improved the targeting of CD4⁺ cells in vivo with fluorescent anti-CD4-antibody-conjugated nanoparticles, the magnetically guided delivery of ferrofluid nanoparticles to subcutaneous tumour allografts and xenografts, and the treatment of subcutaneous tumour allografts with magnetically guided liposomes loaded with doxorubicin and magnetite or with clinically approved 'stealthy' doxorubicin liposomes. The transient and partial blocking of the mononuclear phagocyte system may enhance the performance of a wide variety of nanoparticle drugs.

Reprogrammable fluorescence logic sensing for biomolecules via RNA-like coenzyme A-based coordination polymer

In this study, coenzyme A (CoA)-based coordination polymers (CPs) have been generated in situ by exploiting the reaction of thiols with metal ion (Au(III) or Ag(I)), which are dependent on both thiol-metal and aurophilic metal∙metal interaction. It is interesting to note that CPs-related biosensing capabilities toward some biomolecules including ascorbic acid (AA), cysteine (Cys) and glutathione (GSH) are also investigated via SYBR Green II (SGII)-derived fluorescence switchable mechanisms. The synthesized CPs display especial RNA-like structure and are capable of initiating the fluorescence of SGII. Conversely, AA, Cys or GSH can give rise to the structural destruction of RNA-like CPs, thus inhibiting the fluorescence signal, and quantitative detection of these biomolecules are achieved favorably with a detection limit of 7.2, 0.55 and 0.48 nM, respectively. Meanwhile, the fascinating fluorescence on-off property and simple synthetic process are employed to build a series of basic logic gates (YES, NOT, OR, AND, INHIBIT and NOR) and multiple configurable logic gates (OR-AND and OR-OR-INHIBIT) along with different logic inputs. In view of these, developing CoA-based CPs as a new material to execute logic operations provides a valuable platform to establish the next generation of advanced molecular devices for clinic diagnostic and biomedical research.

Construction of NIR Light Controlled Micelles with Photothermal Conversion Property: Poly(poly(ethylene glycol)methyl ether methacrylate) (PPEGMA) as Hydrophilic Block and Ketocyanine Dye as NIR Photothermal Conversion Agent

Polymeric nanomaterials made from amphiphilic block copolymers are increasingly used in the treatment of tumor tissues. In this work, we firstly synthesized the amphiphilic block copolymer PBnMA-b-P(BAPMA-co-PEGMA) via reversible addition-fragmentation chain transfer (RAFT) polymerization using benzyl methacrylate (BnMA), poly (ethylene glycol) methyl ether methacrylate (PEGMA), and 3-((tert-butoxycarbonyl)amino)propyl methacrylate (BAPMA) as the monomers. Subsequently, PBnMA-b-P(APMA-co-PEGMA)@NIR 800 with photothermal conversion property was obtained by deprotection of the tert-butoxycarbonyl (BOC) groups of PBAPMA chains with trifluoroacetic acid (TFA) and post-modification with carboxyl functionalized ketocyanine dye (NIR 800), and it could self-assemble into micelles in CH3OH/water mixed solvent. The NIR photothermal conversion property of the post-modified micelles were investigated. Under irradiation with NIR light (λmax = 810 nm, 0.028 W/cm2) for 1 h, the temperature of the modified micelles aqueous solution increased to 53 °C from 20 °C, which showed the excellent NIR photothermal conversion property.

Hematite Nanoparticles from Unexpected Reaction of Ferrihydrite with Concentrated Acids for Biomedical Applications

The development of synthetic ways to fabricate nanosized materials with a well-defined shape, narrow-sized distribution, and high stability is of great importance to a rapidly developing area of nanotechnology. Here, we report an unusual reaction between amorphous two-line ferrihydrite and concentrated sulfuric or other mineral and organic acids. Instead of the expected dissolution, we observed the formation of new narrow-distributed brick-red nanoparticles (NPs) of hematite. Different acids produce similar nanoparticles according to scanning (SEM) and transmission electron microscopy (TEM), selected area electron diffraction (SAED), X-ray diffraction (XRD), infrared spectroscopy (FTIR), and energy-dispersive X-ray spectroscopy (EDX). The reaction demonstrates new possibilities for the synthesis of acid-resistant iron oxide nanoparticles and shows a novel pathway for the reaction of iron hydroxide with concentrated acids. The biomedical potential of the fabricated nanoparticles is demonstrated by the functionalization of the particles with polymers, fluorescent labels, and antibodies. Three different applications are demonstrated: i) specific targeting of the red blood cells, e.g., for red blood cell (RBC)-hitchhiking; ii) cancer cell targeting in vitro; iii) infrared ex vivo bioimaging. This novel synthesis route may be useful for the development of iron oxide materials for such specificity-demanding applications such as nanosensors, imaging, and therapy.

Multiple logic operations based on chemically triggered upconversion fluorescence switching

The development of upconversion nanoparticles based logic systems, especially integrated logic systems is still a challenge until now. In this work, an upconversion nanocomposite system is developed and studied for the sensing abilities toward hydrion, hydroxyl ions, metal ions and anions (S^2-, I^-) by taking the advantages of turn-on and turn-off upconversion fluorescence switching response. Triggering by different kinds of ions, the upconversion system can act as a fluorescence switch due to the specific recognition abilities of Rhodamine 6G functionalized PEI for specific ions and the energy transfer process from upconversion nanoparticles to recognition molecules. Based on these results, multiple molecular logic gates, including single-input logic operation (YES, NOT), double-inputs logic operation (OR, AND, NOR, INHIBIT) and multiple-input integrative logic operation (INHIBIT+OR) are developed by employing hydrion, hydroxyl ions, metal ions and anions as inputs and the changes in the upconversion fluorescence intensity as output. The multiple logic operations are of great significance for the applications in biomedicine and molecular calculation.

Nanomagnetic lateral flow assay for high-precision quantification of diagnostically relevant concentrations of serum TSH

Thyroid stimulating hormone (TSH) is the first-line marker for initial evaluation of the thyroid gland function. We present a lateral flow immunoassay based on superparamagnetic nanolabels for rapid (<25 min) quantitative determination of TSH at a point of care. The demonstrated limit of detection (LOD) of 0.017 μIU/mL in human serum is on the level of third-generation TSH laboratory tests. The wide linear dynamic range of more than 3 orders covers the whole range of clinically relevant TSH concentrations for confident quantitative diagnostics of the gland function from hyper- to hypothyroidism, and different states in-between. The attractive values of LOD and linear dynamic range are due to counting of the superparamagnetic nanolabels over the whole reaction volume by their non-linear magnetization at two frequencies of an alternating magnetic field and detecting the response at combinatorial frequencies. The developed cost-efficient and user-friendly immunoassay can be used for express in vitro diagnostics and long-term quantitative monitoring of thyroid dysfunctions, especially in distant regions, developing countries, and sparsely populated areas.

Versatile Sensing Platform for Cd2+ Detection in Rice Samples and Its Applications in Logic Gate Computation

A versatile sensing platform was designed for Cd²⁺ detection utilizing Mg²⁺-dependent DNAzyme as the biocatalyst and toehold-mediated strand replacement as the reaction mechanism. The Cd²⁺-aptamer interaction brings the split subunits of the Mg²⁺-dependent DNAzyme into close-enough proximity, which generates an active DNAzyme that can catalyze the cleavage reaction toward the hairpin substrate strand (H1). The trigger DNA fragment in H1 can open another hairpin probe (H2) to activate the cyclic signal amplification process. The generated numerous G-quadruplex DNAzyme structures will produce a high fluorescence response after incubation with the fluorescence dye N-methyl mesoporphyrin IX (NMM). This detection platform is ultrasensitive and the detection limit (LOD) is 2.5 pM (S/N = 3). The sensing system is robust and can work effectively even in a complex sample matrix, enabling the quantitative analysis of Cd²⁺ content in rice samples with good reliability. Showing the unique features of simple operation, label-free and enzyme-free format, high sensitivity and selectivity, and universal signal amplification mode, our proposed sensing protocol holds great promise for becoming a competitive alternative for the routine monitoring of Cd²⁺ pollution. Importantly, this flexible and versatile sensing platform was used to construct some exquisite logic gates, including AND, OR, INHIBIT, IMPLICATION, NOR, and NAND.

Engineering Stimuli-Activatable Boolean Logic Prodrug Nanoparticles for Combination Cancer Immunotherapy

Prodrug nanoparticles that codeliver the immune modulators to the tumor site are highly recommendable for cancer immunotherapy yet remain challenging. However, effective stimuli-responsive strategies that exploit the endogenous hallmarks of the tumor have paved the way for cancer immunotherapy. For the first time, the development of the Boolean logic prodrug nanoparticles (BLPNs) for tumor-targeted codelivery of immune modulators (e.g., immune activator and immune inhibitor) and combination immunotherapy is reported herein. A library of stimuli-activatable BLPNs is fabricated yielding YES/AND logic outputs by adjusting the input combinations, including extracellular matrix metalloproteins 2/9 (MMP-2/9), intracellular acidity (pH = 5.0-6.0), and reduction (glutathione) in the tumor microenvironment. Tunable and selective control over BLPNs dissociation and prodrug activation is achieved by specifying the connectivity of orthogonal stimuli-labile spacers while exploiting the endogenous signals at the tumor sites. The tumor-specific distribution of the BLPNs and stimuli-activation of the immune modulators for highly efficient cancer immunotherapy are further demonstrated. The results reported in this study may open a new avenue for tumor-specific delivery of immune therapeutics and precise cancer immunotherapy.

Nanoparticle Beacons: Supersensitive Smart Materials with On/Off-Switchable Affinity to Biomedical Targets

Smart materials that can switch between different states under the influence of chemical triggers are highly demanded in biomedicine, where specific responsiveness to biomarkers is imperative for precise diagnostics and therapy. Superior selectivity of drug delivery to malignant cells may be achieved with the nanoagents that stay "inert" until "activation" by the characteristic profile of microenvironment cues (e.g., tumor metabolites, angiogenesis factors, microRNA/DNA, etc.). However, despite a wide variety and functional complexity of smart material designs, their real-life applications are hindered by very limited sensitivity to inputs. Here, we present ultrasensitive smart nanoagents with input-dependent On/Off switchable affinity to a biomedical target based on a combination of gold nanoparticles with low-energy polymer structures. In the proposed method, a nanoparticle-based agent is surface coated with a custom designed flexible polymer chain, which has an input-switchable structure that regulates accessibility of the terminal receptor for target binding. Implementation of the concept with a DNA-model of such polymer has yielded nanoagents that have input-dependent cell-targeting capabilities and responsiveness to as little as 30 fM of DNA input in 15 min lateral flow assay. Thus, we show that surface phenomena can augment nanoagents with capability for switchable affinity without compromising the sensitivity to inputs. The proposed approach is promising for development of next-generation theranostic agents and ultrasensitive nanosensors for point-of-care diagnostics.

Spindle-like MRI-active europium-doped iron oxide nanoparticles with shape-induced cytotoxicity from simple and facile ferrihydrite crystallization procedure

Nanoparticles (NPs) that can provide additional functionality to the nanoagents derived from them, e.g., cytotoxicity or imaging abilities, are in high demand in modern nanotechnology. Here, we report new spindle-like iron oxide nanoparticles doped with Eu3+ that feature magnetic resonance imaging (MRI) contrasting properties together with shape-related cytotoxicity (unusual for such low 2.4% Eu content). The NPs were prepared by a novel procedure for doping of iron oxide nanoparticles based on the crystallization of amorphous ferrihydrite in the presence of hydrated europium(iii) oxide and were thoroughly characterized. Cytotoxicity of low Eu-doped spindle-like hematite nanoparticles was confirmed by MTT assay and further studied in detail by imaging flow cytometry, optical and electron microscopies. Additionally, enhancement of MRI contrast properties of NPs upon doping with europium was demonstrated. According to the MRI using mice as an animal model and direct inductively coupled plasma mass spectrometry (ICP-MS) 153Eu biodistribution measurements, these particles accumulate in the liver and spleen. Therefore, NPs present a novel example of a multimodal component combining magnetic imaging and therapeutic (cytotoxic) abilities for development of theranostic nanoagents.

Antibody-directed metal-organic framework nanoparticles for targeted drug delivery

Nanosized metal-organic frameworks (nMOFs) have shown great promise as high-capacity carriers for a variety of applications. For biomedicine, numerous nMOFs have been proposed that can transport virtually any molecular drug, can finely tune their payload release profile, etc. However, perspectives of their applications for the targeted drug delivery remain relatively unclear. So far, only a few works have reported specific cell targeting by nMOFs exclusively through small ligands such as folic acid or RGD peptides. Here we show feasibility of targeted drug delivery to specific cancer cells in vitro with nMOFs functionalized with such universal tool as an antibody. We demonstrate ca. 120 nm magnetic core/MOFs shell nanoagents loaded with doxorubicin/daunorubicin and coupled with an antibody though a hydrophilic carbohydrate interface. We show that carboxymethyl-dextran coating of nMOFs allows extensive loading of the drug molecules (up to 15.7 mg/g), offers their sustained release in physiological media and preserves antibody specificity. Reliable performance of the agents is illustrated with trastuzumab-guided selective targeting and killing of HER2/neu-positive breast cancer cells in vitro. The approach expands the scope of nMOF applications and can serve as a platform for the development of potent theranostic nanoagents. STATEMENT OF SIGNIFICANCE: The unique combination of exceptional drug capacity and controlled release, biodegradability and low toxicity makes nanosized metal-organic frameworks (nMOFs) nearly ideal drug vehicles for various biomedical applications. Unfortunately, the prospective of nMOF applications for the targeted drug delivery is still unclear since only a few examples have been reported for nMOF cell targeting, exclusively for small ligands. In this work, we fill the important gap and demonstrate nanoagent that can specifically kill target cancer cells via drug delivery based on recognition of HER2/neu cell surface receptors by such universal and specific tool as antibodies. The proposed approach is universal and can be adapted for specific biomedical tasks using antibodies of any specificity and nMOFs of a various composition.

Pyrene derivative-functionalized mesoporous silica-Cu2+ hybrid ensemble for fluorescence "turn-on" detection of H2S and logic gate application in aqueous media

The ensemble system PyH-SBA-15-Cu²⁺ was obtained via coordination interaction of pyrene derivative-functionalized mesoporous SBA-15 and Cu²⁺, and applied for the selective and sensitive detection of H₂S over pH 6.0-12.0 in aqueous media. The sensing strategy was designed on the basis of the H₂S-induced dissolution of Cu²⁺ from PyH-SBA-15-Cu²⁺. Cu²⁺ has good binding affinity to N atoms in PyH-SBA-15; therefore, the organic-inorganic hybrid ensemble PyH-SBA-15-Cu²⁺ was formed, which is nonfluorescent in aqueous solution because of the Cu²⁺-promoted emission quenching of PyH-SBA-15. The addition of H₂S induces the dissolution of PyH-SBA-15-Cu²⁺ by the formation of stable CuS, thereby producing fluorescence revival of PyH-SBA-15. The correlative "turn-on" fluorescence signals of this ensemble system are linearly proportional to [H₂S] in the concentration region of 0-1.0 × 10^-4 M, showing a low detection limit of 3.7 × 10^-7 M. Other common anions do not induce distinct fluorescence changes. When using the fluorescence intensity signal changes of PyH-SBA-15 as outputs and Cu²⁺ and S^2- as inputs, PyH-SBA-15 can act as an XNOR logic gate.

Reactive oxygen species-activatable camptothecin polyprodrug based dextran enhances chemotherapy efficacy by damaging mitochondria

Low loading capacity, poor accumulation rate and weak permeability at tumor sites have been identified as the critical barriers for anti-cancer nanomedicines (ANMs). We herein reported a reactive oxygen species (ROS)-activatable ANM of dextran-b-P(CPTMA-co-OEGMA) (DCPT). It aimed to meet the above challenges for improving the therapeutic efficiency of chemotherapy. In this system, camptothecin (CPT) was selected as a chemotherapy drug and poly(ethylene glycol)methyl ether methacrylate (OEGMA) played the role of a hydrophilic block to enhance the water solubility of polyprodrug micelles. At high ROS levels in the tumor microenvironment, the micelles could be disassembled, and simultaneously, the anti-cancer drug of CPT would be released from the DCPT micelles. The 4T1-tumor growth would be greatly inhibited by these two DCPT polyprodrugs, with outstanding in vivo biosafety. The results of both in vitro and in vivo studies indicated the superior therapeutic effects of DCPT. The rational design of polyprodrug nanomedicines may serve as a promising strategy for the development of tumor microenvironment-responsive ANMs, thus improving chemotherapy efficacy.

Precise Quantitative Analysis of Cell Targeting by Particle-Based Agents Using Imaging Flow Cytometry and Convolutional Neural Network

Understanding the intricacies of particle-cell interactions is essential for many applications such as imaging, phototherapy, and drug/gene delivery, because it is the key to accurate control of the particle properties for the improvement of their therapeutic and diagnostic efficiency. Recently, high-throughput methods have emerged for the detailed investigation of these interactions. For example, imaging flow cytometry (IFC) collects up to 60,000 images of cells per second (in 12 optical channels) and provides information about morphology and organelle localization in combination with fluorescence and side scatter intensity data. However, analysis of IFC data is extremely difficult to perform using conventional methods that calculate integral parameters or use mask-based object recognition. Here, we show application of a convolutional neural network (CNN) for precise quantitative analysis of particle targeting of cells using IFC data. CNN provides high-throughput object detection with almost human precision but avoids the subjective choice of image processing parameters that often leads to incorrect data interpretation. The method allows accurate counting of cell-bound particles with reliable discrimination from the nonbound particles in the field of view. The proposed method expands capabilities of spot counting applications (such as organelle counting, quantification of cell-cell and cell-bacteria interactions) and is going to be useful not only for high-throughput analysis of IFC data but also for other imaging techniques. © 2019 International Society for Advancement of Cytometry.

Dual-Responsive DNA Nanodevice for the Available Imaging of an Apoptotic Signaling Pathway in Situ

Fluorescence imaging tools enable the in situ visualization of those molecules involved in various cell signaling pathways, but directly describing these pathways instead of the separate mediators in situ is much more meaningful and still full of challenges. In this work, a dual-responsive DNA nanodevice that allows the available imaging of an apoptotic signaling pathway in living cells has been developed. The nanodevice is constructed through assembling an elaborately designed Y-shaped DNA (Y-DNA) layer on gold nanoparticles (AuNPs). Only if an apoptotic signaling pathway involving the manganese superoxide dismutase (MnSOD) mRNA and downstream cytochrome c (Cyt c) is presented to serve as the input, the nanodevice can perform an "AND" logic gate operation, disassembling the Y-DNA from the AuNP surface and thereafter outputting a fluorescence signal. In comparison with the fluorescence imaging methods that target individual specific molecules, our strategy allows direct profiling of a specific signaling pathway by connected characterization of two correlative targets. The programmable feature of this strategy also shows the potential for the profiling of other signaling pathways. The concept of studying the line connecting two points will contribute to the systematic interrogation on the signaling networks in situ as the networks are composed of lines instead of individual points.

Carbon Dots for In Vivo Bioimaging and Theranostics

Carbon dots (CDs), a kind of carbon material discovered accidentally, exhibit unexpected advantages in fluorescence imaging/sensing such as photostability, biocompatibility, and low toxicity. For emerging theranostics, an interdiscipline created by integrating therapy and diagnostics, CDs are good candidates when they are combined with targeted chemo/gene/photodynamic/photothermal therapeutic moieties. Here, the development of CDs in nanomedicine is reviewed from their use as original imaging agents and/or drug carriers to multifunctional theranostic systems. Finally, the challenges and prospects of the next-generation of CD-based theranostics for clinical applications are also discussed.

Spatiotemporally Light-Activatable Platinum Nanocomplexes for Selective and Cooperative Cancer Therapy

Highly efficient nanoarchitectures are of great interest for achieving precise chemotherapy with minimized adverse side effects in cancer therapy. However, a major challenge remains in exploring a rational approach to synthesize spatiotemporally selective vehicles for precise cancer chemotherapy. Here, we demonstrate a rational design of bifunctional light-activatable platinum nanocomplexes (PtNCs) that produce dually cooperative cancer therapy through spatiotemporally selective thermo-chemotherapy. The Pt⁴⁺-coordinated polycarboxylic nanogel is explored as the nanoreactor template, which is exploited to synthesize bifunctional PtNCs consisting of a zero-valent Pt⁰ core and a surrounding bivalent Pt²⁺ shell with tunable ratios through a facile and controllable reduction. Without light exposure, chemotherapeutic Pt²⁺ ions are tightly bound on the surface of PtNCs, efficiently reducing undesirable drug leakage and nonselective damage on normal tissues/cells. Upon light exposure, PtNCs generate much heat via photothermal conversion from the Pt⁰ core and simultaneously trigger a rapid release of chemotherapeutic Pt²⁺ ions, thereby leading to the spatiotemporally light-activatable synergistic effect of thermo-chemotherapy. Moreover, PtNCs show enhanced tumor accumulation through the heat-triggered hydrophilicity-hydrophobicity transition upon immediate light exposure after injection, dramatically facilitating in vivo tumor regression through their cooperative anticancer efficiency. This rational design of spatiotemporally activatable nanoparticles provides an insightful tool for precise cancer therapy.

Biocomputing with Nanostructures on Lipid Bilayers

Biocomputation is the algorithmic manipulation of biomolecules. Nanostructures, most notably DNA nanostructures and nanoparticles, become active substrates for biocomputation when modified with stimuli-responsive, programmable biomolecular ligands. This approach-biocomputing with nanostructures ("nano-bio computing")-allows autonomous control of matter and information at the nanoscale; their dynamic assemblies and beneficial properties can be directed without human intervention. Recently, lipid bilayers interfaced with nanostructures have emerged as a new biocomputing platform. This new nano-bio interface, which exploits lipid bilayers as a chemical circuit board for information processing, offers a unique reaction space for realizing nanostructure-based computation at a previously unexplored dimension. In this Concept, recent advances in nano-bio computing are briefly reviewed and the newly emerging concept of biocomputing with nanostructures on lipid bilayers is introduced.

"Green" Synthesis of Cytotoxic Silver Nanoparticles Based on Secondary Metabolites of Lavandula Angustifolia Mill

In this study, we used "green" synthesis to prepare silver nanoparticles (NPs) from aqueous plant and callus extracts of the narrow-leaved lavender Lavandula angustifolia Mill. 35.4 ± 1.6 nm and 56.4 ± 2.4 nm nanoparticles, colloidally stable in phosphate-buffered saline, were synthesized using the plant extract and the callus extract, respectively. NPs were characterized by spectrophotometry, dynamic light scattering, and scanning electron microscopy. We studied the dynamics of the nanoparticle synthesis and evaluated the cytotoxic properties of the plant extract-based NPs. Modification of NPs with bovine serum albumin demonstrated that blockage of the nanoparticle surface completely suppressed NP cytotoxic activity in vitro. The synthesized NPs possess localized surface plasmon resonance properties and are of small sizes, and their surface can be modified with protein molecules, which makes them promising agents for cancer theranostics.