FeSe quantum dots for in vivo multiphoton biomedical imaging

A biodegradable Fe-0.6Se alloy with superior strength and effective antibacterial and antitumor capabilities for orthopedic applications

Iron-selenium (Fe-Se) alloys have potential as attractive biodegradable bone-implant materials, given the antitumor properties of Se in cancer prevention and therapy. However, the fabrication of Fe-Se alloys is challenging due to the volatility of elemental Se and the significantly different melting points of Se and Fe. In this study, we successfully fabricated Fe-xSe (x = 0.2, 0.4, 0.6, 0.8, and 1 wt.%) alloys using suction casting, with FeSe compounds as the Se source. The microstructures, tensile properties, corrosion behavior, biocompatibility, antibacterial ability, and antitumor properties of the Fe-Se alloys were evaluated. The microstructures of the Fe-Se alloys were composed of α-Fe and FeSe phases. Among the Fe-Se alloys, Fe-0.6Se showed the best combination of tensile properties, with a yield strength of 1096.5 ± 7.2 MPa, an ultimate tensile strength of 1271.6 ± 6.3 MPa, and a fracture strain of 15.6 ± 3.3 %, and a degradation rate of 56.9 ± 0.4 μm/year. Moreover, the Fe-0.6Se alloy showed superb antibacterial ability against S. aureus, antitumor activity against 143B osteosarcoma cells, and osteogenicity and biocompatibility toward pre-osteoblast MC3T3-E1 cells. In summary, adding 0.2-1.0 wt.% Se to Fe does not affect the growth of healthy cells but effectively inhibits the growth and reproduction of tumor cells, and the Fe-0.6Se alloy is promising for orthopedic applications owing to its unique combination of mechanical and biofunctional properties. STATEMENT OF SIGNIFICANCE: This work reports on Fe-xSe (x = 0.2, 0.4, 0.6, 0.8, and 1 wt.%) alloys fabricated using suction casting. The microstructures of the Fe-Se alloys were composed of α-Fe and FeSe phases. Among the Fe-Se alloys, the Fe-0.6Se showed the best combination of tensile properties, with a yield strength of 1058.6 ± 3.9 MPa, an ultimate tensile strength of 1134.1 ± 2.9 MPa, and a fracture strain of 16.8 ± 1.5 %, and a degradation rate of 56.9 ± 0.4 μm/year. Moreover, the Fe-0.6Se alloy showed superb antibacterial ability against S. aureus, antitumor activity against 143B osteosarcoma cells, and significant osteogenic ability and biocompatibility toward pre-osteoblast MC3T3-E1 cells. In summary, the Fe-0.6Se alloy is promising for orthopedic applications owing to its unique combination of mechanical and biofunctional properties.

Unlocking multi-photon excited luminescence in pyrazolate trinuclear gold clusters for dynamic cell imaging

The family of coinage-metal-based cyclic trinuclear complexes exhibits abundant photophysical properties, promising for diverse applications. However, their utility in biochemistry is often hindered by large particle size and strong hydrophobicity. Meanwhile, the investigation into multi-photon excited luminescence within this family remained undocumented, limiting their potential in bio-imaging. Herein, we unveil the multi-photon excited luminescent properties of pyrazolate-based trinuclear gold(I) clusters, facilitated by excimeric gold(I)···gold(I) interactions, revealing a nonlinear optical phenomenon within this family. Furthermore, to address issues of poor biocompatibility, we employ electrospinning coupled with hydroxypropyl-beta-cyclodextrin as the matrix to fabricate a flexible, durable, transparent, and red emissive film with a photoluminescence quantum yield as high as 88.3%. This strategy not only produces the film with sufficient hydrophilicity and stability, but also achieves the downsizing of trinuclear gold(I) clusters from microscale to nanoscale. Following the instantaneous dissolution of the film in the media, the released trinuclear gold(I) nanoparticles have illuminated cells and bacteria through a real-time, non-toxic, multi-photon bio-imaging approach. This achievement offers a fresh approach for utilizing coinage-metal-based cyclic trinuclear complexes in biochemical fields.

Diagnosis and treatment status of inoperable locally advanced breast cancer and the application value of inorganic nanomaterials

Locally advanced breast cancer (LABC) is a heterogeneous group of breast cancer that accounts for 10-30% of breast cancer cases. Despite the ongoing development of current treatment methods, LABC remains a severe and complex public health concern around the world, thus prompting the urgent requirement for innovative diagnosis and treatment strategies. The primary treatment challenges are inoperable clinical status and ineffective local control methods. With the rapid advancement of nanotechnology, inorganic nanoparticles (INPs) exhibit a potential application prospect in diagnosing and treating breast cancer. Due to the unique inherent characteristics of INPs, different functions can be performed via appropriate modifications and constructions, thus making them suitable for different imaging technology strategies and treatment schemes. INPs can improve the efficacy of conventional local radiotherapy treatment. In the face of inoperable LABC, INPs have proposed new local therapeutic methods and fostered the evolution of novel strategies such as photothermal and photodynamic therapy, magnetothermal therapy, sonodynamic therapy, and multifunctional inorganic nanoplatform. This article reviews the advances of INPs in local accurate imaging and breast cancer treatment and offers insights to overcome the existing clinical difficulties in LABC management.

Improving Three-Photon Fluorescence of Near-Infrared Quantum Dots for Deep Brain Imaging by Suppressing Biexciton Decay

Three-photon fluorescence microscopy (3PFM) is a promising brain research tool with submicrometer spatial resolution and high imaging depth. However, only limited materials have been developed for 3PFM owing to the rigorous requirement of the three-photon fluorescence (3PF) process. Herein, under the guidance of a band gap engineering strategy, CdTe/CdSe/ZnS quantum dots (QDs) emitting in the near-infrared window are designed for constructing 3PF probes. The formation of type II structure significantly increased the three-photon absorption cross section of QDs and caused the delocalization of electron-hole wave functions. The time-resolved transient absorption spectroscopy confirmed that the decay of biexcitons was significantly suppressed due to the appropriate band gap alignment, which further enhanced the 3PF efficiency of QDs. By utilizing QD-based 3PF probes, high-resolution 3PFM imaging of cerebral vasculature was realized excited by a 1600 nm femtosecond laser, indicating the possibility of deep brain imaging with these 3PF probes.

Emerging potentials of Fe-based nanomaterials for chiral sensing and imaging

Fe-based nanostructures have possessed promising properties that make it suitable for chiral sensing and imaging applications owing to their ultra-small size, non-toxicity, biocompatibility, excellent photostability, tunable fluorescence, and water solubility. This review summarizes the recent research progress in the field of Fe-based nanostructures and places special emphases on their applications in chiral sensing and imaging. The synthetic strategies to prepare the targeted Fe-based structures were also introduced. The chiral sensing and imaging applications of the nanostructures are discussed in details.

Versatile Prepolymer Platform for Controlled Tailoring of Quantum Dot Surface Properties

Quantum dots (QDs) hold immense promise for bioimaging, yet technical challenges in surface engineering limit their wider scientific use. We introduce poly(pentafluorophenyl acrylate) (PPFPA) as a user-friendly prepolymer platform for creating precisely controlled multidentate polymeric ligands for QD surface engineering, accessible to researchers without extensive synthetic expertise. PPFPA combines the benefits of both bottom-up and prepolymer approaches, offering minimal susceptibility to hydrolysis and side reactions for controlled chemical composition, along with simple synthetic procedures using commercially available reagents. Live cell imaging experiments highlighted a significant reduction in nonspecific binding when employing PPFPA, owing to its minimal hydrolysis, in contrast to ligands synthesized by using a conventional prepolymer prone to uncontrolled hydrolysis. This observation underscores the distinct advantage of our prepolymer system. Leveraging PPFPA, we synthesized biomolecule-conjugated QDs and performed QD-based immunofluorescence to detect a cytosolic protein. To effectively label cytosolic targets in such a dense and complex environment, probes must exhibit minimal nonspecific binding and be compact. As a result, QD-immunofluorescence has focused primarily on cell surface targets. By creating compact QD-F(ab')2, we sensitively detected alpha-tubulin with a ∼50-fold higher signal-to-noise ratio compared to organic dye-based labeling. PPFPA represents a versatile and accessible platform for tailoring QD surfaces, offering a pathway to realize the full potential of colloidal QDs in various scientific applications.

Quantum Dot Nanomaterials: Preparation, Characterization, Advanced Bio-Imaging and Therapeutic Applications

The bio-imaging technology is one of the most significant modern applications used in several fields, including early diagnosis of many illnesses that are most important diseases facing humanity and other vital uses. The primary advancement in nanotechnology is the creation of innovative fluorescence probes called quantum dots (QDs). The use of molecular tagging in research, in vivo, and in vitro studies is revolutionized by quantum dots. The application of QD indicates conversion in natural imaging and photography has demonstrated extraordinary appropriateness in bio-imaging, the discovery of novel drugs, and delivery of targeted genes, biosensing, photodynamic therapy, and diagnosis. New potential methods of early cancer detection and treatment management are being researched as a result of the special physical and chemical characteristics of QD probes. The bio-imaging technique depends on the fluorescent emission of the used materials, which is paired with living cells that are easy to see it in 3D without any surgical intervention. Therefore, the use of QDs many types that have unique and appropriate properties for use in that application; In terms of fluorescent emission strength, duration and luminosity.This review article displays some methods of preparation for QDs nanomaterials and the devices used in this. In addition, it presentssome of challenges that must be avoided for the possibility of using them in the bio-imaging field; as toxicity, bio-compatibility, and hydrophilization. It's reviewed some of the devices that use QDs in bio-imaging technique, the QDs application in cell analysis-imaging, and QDs application in vivo imaging.

Two-photon nanoprobes based on bioorganic nanoarchitectonics with a photo-oxidation enhanced emission mechanism

Two-photon absorption (TPA) fluorescence imaging holds great promise in diagnostics and biomedicine owing to its unparalleled spatiotemporal resolution. However, the adaptability and applicability of currently available TPA probes, which act as a critical element for determining the imaging contrast effect, is severely challenged by limited photo-luminescence in vivo. This is particularly a result of uncontrollable aggregation that causes fluorescence quenching, and inevitable photo-oxidation in harsh physiological milieu, which normally leads to bleaching of the dye. Herein, we describe the remarkably enhanced TPA fluorescence imaging capacity of self-assembling near-infrared (NIR) cyanine dye-based nanoprobes (NPs), which can be explained by a photo-oxidation enhanced emission mechanism. Singlet oxygen generated during photo-oxidation enables chromophore dimerization to form TPA intermediates responsible for enhanced TPA fluorescence emission. The resulting NPs possess uniform size distribution, excellent stability, more favorable TPA cross-section and anti-bleaching ability than a popular TPA probe rhodamine B (RhB). These properties of cyanine dye-based TPA NPs promote their applications in visualizing blood circulation and tumoral accumulation in real-time, even to cellular imaging in vivo. The photo-oxidation enhanced emission mechanism observed in these near-infrared cyanine dye-based nanoaggregates opens an avenue for design and development of more advanced TPA fluorescence probes.

Durable organic nonlinear optical membranes for thermotolerant lightings and in vivo bioimaging

Organic nonlinear optical materials have potential in applications such as lightings and bioimaging, but tend to have low photoluminescent quantum yields and are prone to lose the nonlinear optical activity. Herein, we demonstrate to weave large-area, flexible organic nonlinear optical membranes composed of 4-N,N-dimethylamino-4'-N'-methyl-stilbazolium tosylate@cyclodextrin host-guest supramolecular complex. These membranes exhibited a record high photoluminescence quantum yield of 73.5%, and could continuously emit orange luminescence even being heated at 300 °C, thus enabling the fabrication of thermotolerant light-emitting diodes. The nonlinear optical property of these membranes can be well-preserved even in polar environment. The supramolecular assemblies with multiphoton absorption characteristics were used for in vivo real-time imaging of Escherichia coli at 1000 nm excitation. These findings demonstrate to achieve scalable fabrication of organic nonlinear optical materials with high photoluminescence quantum yields, and good stability against thermal stress and polar environment for high-performance, durable optoelectronic devices and humanized multiphoton bio-probes.

Recent trends in macromolecule-conjugated hybrid quantum dots for cancer theranostic applications

Quantum dots (QDs) are small nanoparticles with semiconductor properties ranging from 2 to 10 nanometers comprising 10-50 atoms. The single wavelength excitation character of QDs makes it more significant, as it can excite multiple particles in a confined surface simultaneously by narrow emission. QDs are more photostable than traditional organic dyes; however, when injected into tissues, whole animals, or ionic solutions, there is a significant loss of fluorescence. HQD-based probes conjugated with cancer-specific ligands, antibodies, or peptides are used in clinical diagnosis. It is more precise and reliable than standard immunohistochemistry (IHC) at minimal protein expression levels. Advanced clinical studies use photodynamic therapy (PDT) with fluorescence imaging to effectively identify and treat cancer. Recent studies revealed that a combination of unique characteristics of QDs, including their fluorescence capacity and abnormal expression of miRNA in cancer cells, were used for the detection and monitoring progression of cancer. In this review, we have highlighted the unique properties of QDs and the theranostic behavior of various macromolecule-conjugated HQDs leading to cancer treatment.

Self-Organization of Iron Sulfide Nanoparticles into Complex Multicompartment Supraparticles

Self-assembled compartments from nanoscale components are found in all life forms. Their characteristic dimensions are in 50-1000 nm scale, typically assembled from a variety of bioorganic "building blocks". Among the various functions that these mesoscale compartments carry out, protection of the content from the environment is central. Finding synthetic pathways to similarly complex and functional particles from technologically friendly inorganic nanoparticles (NPs) is needed for a multitude of biomedical, biochemical, and biotechnological processes. Here, it is shown that FeS2 NPs stabilized by l-cysteine self-assemble into multicompartment supraparticles (mSPs). The NPs initially produce ≈55 nm concave assemblies that reconfigure into ≈75 nm closed mSPs with ≈340 interconnected compartments with an average size of ≈5 nm. The intercompartmental partitions and mSP surface are formed primarily from FeS2 and Fe2 O3 NPs, respectively. The intermediate formation of cup-like particles enables encapsulation of biological cargo. This capability is demonstrated by loading mSPs with DNA and subsequent transfection of mammalian cells. Also it is found that the temperature stability of the DNA cargo is enhanced compared to the traditional delivery vehicles. These findings demonstrate that biomimetic compartmentalized particles can be used to successfully encapsulate and enhance temperature stability of the nucleic acid cargo for a variety of bioapplications.

Chiral Spectroscopy of Nanostructures

ConspectusChirality is ubiquitous in the universe and in living creatures over detectable length scales from the subatomic to the galactic, as exemplified in the two extremes by subatomic particles (neutrinos) and spiral galaxies. Between them are living creatures that display multiple levels of chirality emerging from hierarchically assembled asymmetric building blocks. Not too far from the bottom of this pyramid are the foundational building blocks with chiral atomic centers on sp³ carbon atoms exemplified by l-amino acids and d-sugars that are self-assembled into higher-order structures with increasing dimensions forming highly complex, amazingly functional, and energy-efficient living systems. The organization and materials employed in their construction inspired scientists to replicate complex living systems via the self-assembly of chiral components. Multiple studies pointed to unexpected and unique electromagnetic properties of chiral structures with nanoscale and microscale dimensions, including giant circular dichroism and collective circularly polarized scattering that their constituent units did not possess.To address the wide variety of chiral geometries observed in continuous materials, singular particles, and their complex systems, multiple analytic techniques are needed. Simultaneously, their spectroscopic properties create a pathway to multiple applications. For example, mirror-asymmetric vibrations at chiral centers formed by sp³ carbon atoms lead to optical activity for the infrared (IR) wavelength regions. At the same time, understanding the optical activity in, for example, the IR region enables biomedical applications because multiple modalities of biomedical imaging and vibrational optical activity (VOA) of biomolecules are known for IR range. In turn, VOA can be realized in both absorption and emission modalities due to large magnetic transition moments, as vibrational circular dichroism (VCD) or Raman optical activity (ROA) spectroscopy. In addition to the VOA, in the range of longer wavelengths, lattice vibrational mode or phononic behavior occurs in chiral crystals and nanoassemblies, which can be readily detected by terahertz circular dichroism (TCD) spectroscopy. Meanwhile, chiral self-assembly can induce circularly polarized light emission (CPLE) regardless of the existence of chirality in coassembled fluorophores. The CPLE from self-assembled chiral materials is particularly interesting because the CPLE can originate from both circularly polarized luminescence and circularly polarized scattering (CPS). Furthermore, because self-assembled nanostructures often exhibit stronger optical activity than their building blocks owing to dimension and resonance effects, the optical activity of single assembled nanostructures can be investigated by using microscopic technology combined with chiral optics. Here, we describe the state of the art for spectroscopic methods for the comprehensive analysis of chiral nanomaterials at various photon wavelengths, addressed with special attention given to new tools emerging both for materials with self-organized hierarchical chirality and single-particle spectroscopy.

Nontoxic Fluorescent Nanoprobes for Multiplexed Detection and 3D Imaging of Tumor Markers in Breast Cancer

Multiplexed fluorescent immunohistochemical analysis of breast cancer (BC) markers and high-resolution 3D immunofluorescence imaging of the tumor and its microenvironment not only facilitate making the disease prognosis and selecting effective anticancer therapy (including photodynamic therapy), but also provides information on signaling and metabolic mechanisms of carcinogenesis and helps in the search for new therapeutic targets and drugs. The characteristics of imaging nanoprobe efficiency, such as sensitivity, target affinity, depth of tissue penetration, and photostability, are determined by the properties of their components, fluorophores and capture molecules, and by the method of their conjugation. Regarding individual nanoprobe components, fluorescent nanocrystals (NCs) are widely used for optical imaging in vitro and in vivo, and single-domain antibodies (sdAbs) are well established as highly specific capture molecules in diagnostic and therapeutic applications. Moreover, the technologies of obtaining functionally active sdAb–NC conjugates with the highest possible avidity, with all sdAb molecules bound to the NC in a strictly oriented manner, provide 3D-imaging nanoprobes with strong comparative advantages. This review is aimed at highlighting the importance of an integrated approach to BC diagnosis, including the detection of biomarkers of the tumor and its microenvironment, as well as the need for their quantitative profiling and imaging of their mutual location, using advanced approaches to 3D detection in thick tissue sections. The existing approaches to 3D imaging of tumors and their microenvironment using fluorescent NCs are described, and the main comparative advantages and disadvantages of nontoxic fluorescent sdAb–NC conjugates as nanoprobes for multiplexed detection and 3D imaging of BC markers are discussed.

Multiphoton excited singlet/triplet mixed self-trapped exciton emission

Multiphoton excited luminescence is of paramount importance in the field of optical detection and biological photonics. Self-trapped exciton (STE) emission with self-absorption-free advantages provide a choice for multiphoton excited luminescence. Herein, multiphoton excited singlet/triplet mixed STE emission with a large full width at half-maximum (617 meV) and Stokes shift (1.29 eV) has been demonstrated in single-crystalline ZnO nanocrystals. Temperature dependent steady state, transient state and time-resolved electron spin resonance spectra demonstrate a mixture of singlet (63%) and triplet (37%) mixed STE emission, which contributes to a high photoluminescence quantum yield (60.5%). First-principles calculations suggest 48.34 meV energy per exciton stored by phonons in the distorted lattice of excited states, and 58 meV singlet-triplet splitting energy for the nanocrystals being consistent with the experimental measurements. The model clarifies long and controversial debates on ZnO emission in visible region, and the multiphoton excited singlet/triplet mixed STE emission is also observed.

Quantitative Detection of Gastrointestinal Tumor Markers Using a Machine Learning Algorithm and Multicolor Quantum Dot Biosensor

This work was to explore the application value of gastrointestinal tumor markers based on gene feature selection model of principal component analysis (PCA) algorithm and multicolor quantum dots (QDs) immunobiosensor in the detection of gastrointestinal tumors. Based on the PCA method, the neighborhood rough set algorithm was introduced to improve it, and the tumor gene feature selection model (OPCA) was established to analyze its classification accuracy and accuracy. Four kinds of coupled biosensors were fabricated based on QDs, namely, 525 nm Cd Se/Zn S QDs-carbohydrate antigen 125 (QDs525-CA125 McAb), 605 nm Cd Se/Zn S QDs-cancer antigen 19-9 (QDs605-CA19-9 McAb), 645 nm Cd Se/Zn S QDs-anticancer embryonic antigen (QDs 645-CEA McAb), and 565 nm Cd Se/Zn S QDs-anti-alpha-fetoprotein (QDs565-AFP McAb). The quantum dot-antibody conjugates were identified and quantified by fluorescence spectroscopy and ultraviolet absorption spectroscopy. The results showed that the classification precision of OPCA model in colon tumor and gastric cancer datasets was 99.52% and 99.03%, respectively, and the classification accuracy was 94.86% and 94.2%, respectively, which were significantly higher than those of other algorithms. The fluorescence values of AFP McAb, CEA McAb, CA19-9 McAb, and CA125 McAb reached the maximum when the conjugation concentrations were 25 µg/mL, 20 µg/mL, 30 µg/mL, and 30 µg/m, respectively. The highest recovery rate of AFP was 98.51%, and its fluorescence intensity was 35.78 ± 2.99, which was significantly higher than that of other antigens (P < 0.001). In summary, the OPCA model based on PCA algorithm can obtain fewer feature gene sets and improve the accuracy of sample classification. Intelligent immunobiosensors based on machine learning algorithms and QDs have potential application value in gastrointestinal gene feature selection and tumor marker detection, which provides a new idea for clinical diagnosis of gastrointestinal tumors.

Fibrous aggregates: Amplifying aggregation-induced emission to boost health protection

Environmental monitoring and personal protection are critical for preventing and for protecting human health during all infectious disease outbreaks (including COVID-19). Fluorescent probes combining sensing, imaging and therapy functions, could not only afford direct visualizing existence of biotargets and monitoring their dynamic information, but also provide therapeutic functions for killing various bacteria or viruses. Luminogens with aggregation-induced emission (AIE) could be well suited for above requirements because of their typical photophysical properties and therapeutic functions. Integration of these molecules with fibers or textiles is of great interest for developing flexible devices and wearable systems. In this review, we mainly focus on how fibers and AIEgens to be combined for health protection based on the latest advances in biosensing and bioprotection. We first discuss the construction of fibrous sensors for visualization of biomolecules. Next recent advances in therapeutic fabrics for individual protection are introduced. Finally, the current challenges and future opportunities for "AIE + Fiber" in sensing and therapeutic applications are presented.

Antibody-Incorporated Nanomedicines for Cancer Therapy

Antibody-based cancer therapy, one of the most significant therapeutic strategies, has achieved considerable success and progress over the past decades. Nevertheless, obstacles including limited tumor penetration, short circulation half-lives, undesired immunogenicity, and off-target side effects remain to be overcome for the antibody-based cancer treatment. Owing to the rapid development of nanotechnology, antibody-containing nanomedicines that have been extensively explored to overcome these obstacles have already demonstrated enhanced anticancer efficacy and clinical translation potential. This review intends to offer an overview of the advancements of antibody-incorporated nanoparticulate systems in cancer treatment, together with the nontrivial challenges faced by these next-generation nanomedicines. Diverse strategies of antibody immobilization, formats of antibodies, types of cancer-associated antigens, and anticancer mechanisms of antibody-containing nanomedicines are provided and discussed in this review, with an emphasis on the latest applications. The current limitations and future research directions on antibody-containing nanomedicines are also discussed from different perspectives to provide new insights into the construction of anticancer nanomedicines.

Selenopeptide Nanomedicine Activates Natural Killer Cells for Enhanced Tumor Chemoimmunotherapy

Chemoimmunotherapy using nanotechnology has shown great potential for cancer therapy in the clinic. However, uncontrolled transportation and synergistic responses remain challenges. Here, a self-assembled selenopeptide nanoparticle that strengthens tumor chemoimmunotherapy through the activation of natural killer (NK) cells by the oxidative metabolite of the selenopeptide is developed. With the advantages of the enzyme-induced size-reduction and the reactive-oxygen-species-driven deselenization, this selenopeptide is able to deliver therapeutics, e.g., doxorubicin (DOX), to solid tumors and further activate the NK cells in a programmed manner. Importantly, in vitro and in vivo results prove the mutual promotion between the DOX-induced chemotherapy and the selenopeptide-induced immunotherapy, which synergistically contribute to the improved antitumor efficacy. It is anticipated that the selenopeptide may provide a type of promising stimuli-responsive immune modulator for versatile biomedical applications.

Multiphoton excitation imaging via an actively mode-locked tunable fiber-cavity SOA laser around 800 nm

In this study, an active mode-locked tunable pulsed laser (AML-TPL) is proposed to excite picosecond pulsed light with a rapid wavelength tunability of approximately 800 nm for multiphoton microscopy. The AML-TPL is schematically based on a fiber-cavity semiconductor optical amplifier (SOA) configuration to implement a robust and align-free pulsed light source with a duration of 1.6 ps, a repetition rate of 27.9271 MHz, and average output power of over 600 mW. A custom-built multiphoton imaging system was also built to demonstrate the imaging performance of the proposed AML-TPL by comparing with the commercial Ti:Sapphire femtosecond laser. Two-photon excited fluorescence images were successfully acquired using a human breast cancer cell line (MDA-MB-231) stained with acridine orange.

Versatile Types of Inorganic/Organic NIR-IIa/IIb Fluorophores: From Strategic Design toward Molecular Imaging and Theranostics

In vivo imaging in the second near-infrared window (NIR-II, 1000-1700 nm), which enables us to look deeply into living subjects, is producing marvelous opportunities for biomedical research and clinical applications. Very recently, there has been an upsurge of interdisciplinary studies focusing on developing versatile types of inorganic/organic fluorophores that can be used for noninvasive NIR-IIa/IIb imaging (NIR-IIa, 1300-1400 nm; NIR-IIb, 1500-1700 nm) with near-zero tissue autofluorescence and deeper tissue penetration. This review provides an overview of the reports published to date on the design, properties, molecular imaging, and theranostics of inorganic/organic NIR-IIa/IIb fluorophores. First, we summarize the design concepts of the up-to-date functional NIR-IIa/IIb biomaterials, in the order of single-walled carbon nanotubes (SWCNTs), quantum dots (QDs), rare-earth-doped nanoparticles (RENPs), and organic fluorophores (OFs). Then, these novel imaging modalities and versatile biomedical applications brought by these superior fluorescent properties are reviewed. Finally, challenges and perspectives for future clinical translation, aiming at boosting the clinical application progress of NIR-IIa and NIR-IIb imaging technology are highlighted.

Nanocarrier-based Drug Delivery System for Cancer Therapeutics: A Review of the Last Decade

In recent years, due to the shortcomings of conventional chemotherapy, such as poor bioavailability, low treatment index, and unclear side effects, the focus of cancer research has shifted to new nanocarriers of chemotherapeutic drugs. By using biodegradable materials, nanocarriers generally have the advantages of good biocompatibility, low side effects, targeting, controlled release profile, and improved efficacy. More to the point, nanocarrier based anti-cancer drug delivery systems clearly show the potential to overcome the problems associated with conventional chemotherapy. In order to promote the in-depth research and development in this field, we herein summarized and analyzed various nanocarrier based drug delivery systems for cancer therapy, including the concepts, types, characteristics, and preparation methods. The active and passive targeting mechanisms of cancer therapy were also included, along with a brief introduction of the research progress of nanocarriers used for anti-cancer drug delivery in the past decade.

Reverse bandgap-bowing in nickel-cadmium sulfide alloys (Ni1-xCdxS) and its origin

We present evolution of band energies in α-NiS when alloyed with a cationic doping through isovalent cadmium (Cd²⁺). Optical bandgap of nickel-cadmium sulfide (Ni_1-xCd_xS) alloys, as a deviation from the linear relationship or Vegard's law, have exhibited a reverse bandgap-bowing in the form of downward-concave dependence. Such a phenomenon, which manifests as a negative value of bowing coefficient (b), is uncommon in chalcogenide alloys. In this work, we have deliberated on the origin of reverse bandgap-bowing in nickel-cadmium alloys and identified the band responsible for the bowing phenomenon. While thin-films of the alloys were formed through successive ionic layer adsorption and reaction method, tunnel conductance and thereby density of states of the materials were derived from scanning tunneling spectroscopy. The spectroscopy provided the variation of conduction and valence band-edges (CB and VB, respectively) with respect to the cadmium-content in Ni_1-xCd_xS. The CB-edge of the alloys could be seen to remain mostly unaffected with increasing cadmium-content, since the band is composed of only the S 2porbitals; the VB-energy, on the other hand, which forms due to an effective coupling between the metaldand the anionporbitals, could be seen to be affected due to ap-drepulsion. Based on our experimental findings, we inferred that an antagonism between volume deformation and structural relaxation had resulted in the reverse bandgap-bowing in Ni_1-xCd_xS alloys.

Light-Interacting iron-based nanomaterials for localized cancer detection and treatment

To improve the prognosis of cancer patients, methods of local cancer detection and treatment could be implemented. For that, iron-based nanomaterials (IBN) are particularly well-suited due to their biocompatibility and the various ways in which they can specifically target a tumor, i.e. through passive, active or magnetic targeting. Furthermore, when it is needed, IBN can be associated with well-known fluorescent compounds, such as dyes, clinically approved ICG, fluorescent proteins, or quantum dots. They may also be excited and detected using well-established optical methods, relying on scattering or fluorescent mechanisms, depending on whether IBN are associated with a fluorescent compound or not. Systems combining IBN with optical methods are diverse, thus enabling tumor detection in various ways. In addition, these systems provide a wealth of information, which is inaccessible with more standard diagnostic tools, such as single tumor cell detection, in particular by combining IBN with near-field scanning optical microscopy, dark-field microscopy, confocal microscopy or super-resolution microscopy, or the highlighting of certain dynamic phenomena such as the diffusion of a fluorescent compound in an organism, e.g. using fluorescence lifetime imaging, fluorescence resonance energy transfer, fluorescence anisotropy, or fluorescence tomography. Furthermore, they can in some cases be complemented by a therapeutic approach to destroy tumors, e.g. when the fluorescent compound is a drug, or when a technique such as photo-thermal or photodynamic therapy is employed. This review brings forward the idea that iron-based nanomaterials may be associated with various optical techniques to form a commercially available toolbox, which can serve to locally detect or treat cancer with a better efficacy than more standard medical approaches. STATEMENT OF SIGNIFICANCE: New tools should be developed to improve cancer treatment outcome. For that, two closely-related aspects deserve to be considered, i.e. early tumor detection and local tumor treatment. Here, I present various types of iron-based nanomaterials, which can achieve this double objective when they interact with a beam of light under specific and accurately chosen conditions. Indeed, these materials are biocompatible and can be used/combined with most standard microscopic/optical methods. Thus, these systems enable on the one hand tumor cell detection with a high sensitivity, i.e. down to single tumor cell level, and on the other hand tumor destruction through various mechanisms in a controlled and localized manner by deciding whether or not to apply a beam of light and by having these nanomaterials specifically target tumor cells.

Insights into colloidal nanoparticle-protein corona interactions for nanomedicine applications

Colloidal nanoparticles (NPs) have attracted significant attention due to their unique physicochemical properties suitable for diagnosing and treating different human diseases. Nevertheless, the successful implementation of NPs in medicine demands a proper understanding of their interactions with the different proteins found in biological fluids. Once introduced into the body, NPs are covered by a protein corona (PC) that determines the biological behavior of the NPs. The formation of the PC can eventually favor the rapid clearance of the NPs from the body before fulfilling the desired objective or lead to increased cytotoxicity. The PC nature varies as a function of the different repulsive and attractive forces that govern the NP-protein interaction and their colloidal stability. This review focuses on the phenomenon of PC formation on NPs from a physicochemical perspective, aiming to provide a general overview of this critical process. Main issues related to NP toxicity and clearance from the body as a result of protein adsorption are covered, including the most promising strategies to control PC formation and, thereby, ensure the successful application of NPs in nanomedicine.

Emerging Magnetic Interactions in van der Waals Heterostructures

Vertical van der Waals (vdWs) heterostructures based on layered materials are attracting interest as a new class of quantum materials, where interfacial charge-transfer coupling can give rise to fascinating strongly correlated phenomena. Transition metal chalcogenides are a particularly exciting material family, including ferromagnetic semiconductors, multiferroics, and superconductors. Here, we report the growth of an organic-inorganic heterostructure by intercalating molecular electron donating bis(ethylenedithio)tetrathiafulvalene into (Li,Fe)OHFeSe, a layered material in which the superconducting ground state results from the intercalation of hydroxide layer. Molecular intercalation in this heterostructure induces a transformation from a paramagnetic to spin-glass-like state that is sensitive to the stoichiometry of molecular donor and an applied magnetic field. Besides, electron-donating molecules reduce the electrical resistivity in the heterostructure and modify its response to laser illumination. This hybrid heterostructure provides a promising platform to study emerging magnetic and electronic behaviors in strongly correlated layered materials.

A magnetically responsive drug-loaded nanocatalyst with cobalt-involved redox for the enhancement of tumor ferrotherapy

A magnetic-field-responsive nanocatalyst with Co-involved redox was constructed to amplify the effects of tumor ferrotherapy.