Nanotheranostics and image-guided drug delivery: current concepts and future directions

Corked Microcapsules Enabling Controlled Ultrasound-Mediated Protein Delivery

While ultrasound represents a facile, portable, and noninvasive trigger for drug delivery vehicles, most reported ultrasound-triggered drug delivery vehicles predominately present "burst" release profiles that are hard to control after the initial activation stimulus. Herein, we report a submerged electrospraying technique to fabricate protein-loaded microcapsules in which silica "corks" are embedded within the microcapsule shell. Upon the application of an ultrasound trigger, the corks can be perturbed within the shell, allowing for the release of the protein payload through a phantom tissue mimic to a degree proportional to the number/time of pulses applied. Specifically, multiple ultrasound pulses were shown to enable a 15- to 23-fold increase in the rate of release of the model bovine serum albumin protein payload relative to no ultrasound being applied, with release returning to a lower level when the ultrasound stimulus was removed. Coupled with the low cytotoxicity of the vehicle components, the corked microcapsules show promise for expanding the potential to use ultrasound to facilitate both on-demand and pulsatile release profiles.

[68Ga]Ga-THP-tetrazine for bioorthogonal click radiolabelling: pretargeted PET imaging of liposomal nanomedicines

Pretargeted PET imaging using bioorthogonal chemistry is a leading strategy for the tracking of long-circulating agents such as antibodies and nanoparticle-drug delivery systems with short-lived isotopes. Here, we report the synthesis, characterisation and in vitro/vivo evaluation of a new 68Ga-based radiotracer [68Ga]Ga-THP-Tetrazine ([68Ga]Ga-THP-Tz) for bioorthogonal click radiochemistry and in vivo labelling of agents with slow pharmacokinetics. THP-tetrazine (THP-Tz) can be radiolabelled to give [68/67Ga]Ga-THP-Tz at room temperature in less than 15 minutes with excellent radiochemical stability in vitro and in vivo. [68Ga]Ga-THP-Tz was tested in vitro and in vivo for pretargeted imaging of stealth PEGylated liposomes, chosen as a leading clinically-approved platform of nanoparticle-based drug delivery, and for their known long-circulating properties. To achieve this, PEGylated liposomes were functionalised with a synthesised transcyclooctene (TCO) modified phospholipid. Radiolabelling of TCO-PEG-liposomes with [68/67Ga]Ga-THP-Tz was demonstrated in vitro in human serum, and in vivo using both healthy mice and in a syngeneic cancer murine model (WEHI-164 fibrosarcoma). Interestingly in vivo data revealed that [68Ga]Ga-THP-Tz was able to in vivo radiolabel liposomes present in the liver and spleen, and not those in the blood pool or in the tumour. Overall, these results demonstrate the potential of [68Ga]Ga-THP-Tz for pretargeted imaging/therapy but also some unexpected limitations of this system.

Triplet-Triplet Annihilation Upconverting Liposomes: Mechanistic Insights into the Role of Membranes in Two-Dimensional TTA-UC

Triplet-triplet annihilation upconversion (TTA-UC) implemented in nanoparticle assemblies is of emerging interest in biomedical applications, including in drug delivery and imaging. As it is a bimolecular process, ensuring sufficient mobility of the sensitizer and annihilator to facilitate effective collision in the nanoparticle is key. Liposomes can provide the benefits of two-dimensional confinement and condensed concentration of the sensitizer and annihilator along with superior fluidity compared to other nanoparticle assemblies. They are also biocompatible and widely applied across drug delivery modalities. However, there are relatively few liposomal TTA-UC systems reported to date, so systematic studies of the influence of the liposomal environment on TTA-UC are currently lacking. Here, we report the first example of a BODIPY-based sensitizer TTA-UC system within liposomes and use this system to study TTA-UC generation and compare the relative intensity of the anti-Stokes signal for this system as a function of liposome composition and membrane fluidity. We report for the first time on time-resolved spectroscopic studies of TTA-UC in membranes. Nanosecond transient absorption data reveal the BODIPY-perylene dyad sensitizer has a long triplet lifetime in liposome with contributions from three triplet excited states, whose lifetimes are reduced upon coinclusion of the annihilator due to triplet-triplet energy transfer, to a greater extent than in solution. This indicates triplet energy transfer between the sensitizer and the annihilator is enhanced in the membrane system. Molecular dynamics simulations of the sensitizer and annihilator TTA collision complex are modeled in the membrane and confirm the co-orientation of the pair within the membrane structure and that the persistence time of the bound complex exceeds the TTA kinetics. Modeling also reliably predicted the diffusion coefficient for the sensitizer which matches closely with the experimental values from fluorescence correlation spectroscopy. The relative intensity of the TTA-UC output across nine liposomal systems of different lipid compositions was explored to examine the influence of membrane viscosity on upconversion (UC). UC showed the highest relative intensity for the most fluidic membranes and the weakest intensity for highly viscous membrane compositions, including a phase separation membrane. Overall, our study reveals that the co-orientation of the UC pair within the membrane is crucial for effective TTA-UC within a biomembrane and that the intensity of the TTA-UC output can be tuned in liposomal nanoparticles by modifying the phase and fluidity of the liposome. These new insights will aid in the design of liposomal TTA-UC systems for biomedical applications.

Self-Assembled Fluorinated Nanoparticles as Sensitive and Biocompatible Theranostic Platforms for 19F MRI

Theranostics is a novel paradigm integrating therapy and diagnostics, thereby providing new prospects for overcoming the limitations of traditional treatments. In this context, perfluorocarbons (PFCs) are the most widely used tracers in preclinical fluorine-19 magnetic resonance (19F MR), primarily for their high fluorine content. However, PFCs are extremely hydrophobic, and their solutions often display reduced biocompatibility, relative instability, and subpar 19F MR relaxation times. This study aims to explore the potential of micellar 19F MR imaging (MRI) tracers, synthesized by polymerization-induced self-assembly (PISA), as alternative theranostic agents for simultaneous imaging and release of the non-steroidal antileprotic drug clofazimine. In vitro, under physiological conditions, these micelles demonstrate sustained drug release. In vivo, throughout the drug release process, they provide a highly specific and sensitive 19F MRI signal. Even after extended exposure, these fluoropolymer tracers show biocompatibility, as confirmed by the histological analysis. Moreover, the characteristics of these polymers can be broadly adjusted by design to meet the wide range of criteria for preclinical and clinical settings. Therefore, micellar 19F MRI tracers display physicochemical properties suitable for in vivo imaging, such as relaxation times and non-toxicity, and high performance as drug carriers, highlighting their potential as both diagnostic and therapeutic tools.

Unveiling the potentials of hydrophilic and hydrophobic polymers in microparticle systems: Opportunities and challenges in processing techniques

Conventional drug delivery systems are associated with various shortcomings, including low bioavailability and limited control over release. Biodegradable polymeric microparticles have emerged as versatile carriers in drug delivery systems addressing all these challenges. This comprehensive review explores the dynamic landscape of microparticles, considering the role of hydrophilic and hydrophobic materials. Within the continuously evolving domain of microparticle preparation methods, this review offers valuable insights into the latest advancements and addresses the factors influencing microencapsulation, which is pivotal for harnessing the full potential of microparticles. Exploration of the latest research in this dynamic field unlocks the possibilities of optimizing microencapsulation techniques to produce microparticles of desired characteristics and properties for different applications, which can help contribute to the ongoing evolution in the field of pharmaceutical science.

Solvent-Dependent Emissions Properties of a Model Aurone Enable Use in Biological Applications

Fluorophores are powerful visualization tools and the development of novel small organic fluorophores are in great demand. Small organic fluorophores have been derived from the aurone skeleton, 2-benzylidenebenzofuran-3(2H)-one. In this study, we have utilized a model aurone derivative with a methoxy group at the 3' position and a hydroxyl group at the 4' position, termed vanillin aurone, to develop a foundational understanding of structural factors impacting aurone fluorescence properties. The fluorescent behaviors of the model aurone were characterized in solvent environments differing in relative polarity and dielectric constant. These data suggested that hydrogen bonding or electrostatic interactions between excited state aurone and solvent directly impact emissions properties such as peak emission wavelength, emission intensity, and Stokes shift. Time-dependent Density Functional Theory (TD-DFT) model calculations suggest that quenched aurone emissions observed in water are a consequence of stabilization of a twisted excited state conformation that disrupts conjugation. In contrast, the calculations indicate that low polarity solvents such as toluene or acetone stabilize a brightly fluorescent planar state. Based on this, additional experiments were performed to demonstrate use as a turn-on probe in an aqueous environment in response to conditions leading to planar excited state stabilization. Vanillin aurone was observed to bind to a model ATP binding protein, YME1L, leading to enhanced emissions intensities with a dissociation equilibrium constant equal to ~ 30 µM. Separately, the aurone was observed to be cell permeable with significant toxicity at doses exceeding 6.25 µM. Taken together, these results suggest that aurones may be broadly useful as turn-on probes in aqueous environments that promote either a change in relative solvent polarity or through direct stabilization of a planar excited state through macromolecular binding.

Construction of intelligent drug delivery system based on polysaccharide-derived polymer micelles: A review

Micelles are nanostructures developed via the spontaneous assembly of amphiphilic polymers in aqueous systems, which possess the advantages of high drug stability or active-ingredient solubilization, targeted transport, controlled release, high bioactivity, and stability. Polysaccharides have excellent water solubility, biocompatibility, and degradability, and can be modified to achieve a hydrophobic core to encapsulate hydrophobic drugs, improve drug biocompatibility, and achieve regulated delivery of the loaded drug. Micelles drug delivery systems based on polysaccharides and their derivatives show great potential in the biomedical field. This review discusses the principles of self-assembly of amphiphilic polymers and the formation of micelles; the preparation of amphiphilic polysaccharides is described in detail, and an overview of common polysaccharides and their modifications is provided. We focus on the review of strategies for encapsulating drugs in polysaccharide-derived polymer micelles (PDPMs) and building intelligent drug delivery systems. This review provides new research directions that will help promote future research and development of PDPMs in the field of drug carriers.

A detailed insight of the tumor targeting using nanocarrier drug delivery system

Human struggle against the deadly disease conditions is continued since ages. The contribution of science and technology in fighting against these diseases cannot be ignored exclusively due to the invention of novel procedure and products, extending their size ranges from micro to nano. Recently nanotechnology has been gaining more consideration for its ability to diagnose and treat different cancers. Different nanoparticles have been used to evade the issues related with conservative anticancer delivery systems, including their nonspecificity, adverse effects and burst release. These nanocarriers including, solid lipid nanoparticles (SLNs), liposomes, nano lipid carriers (NLCs), nano micelles, nanocomposites, polymeric and magnetic nanocarriers, have brought revolutions in antitumor drug delivery. Nanocarriers improved the therapeutic efficacy of anticancer drugs with better accumulation at the specific site with sustained release, improved bioavailability and apoptosis of the cancer cells while bypassing the normal cells. In this review, the cancer targeting techniques and surface modification on nanoparticles are discussed briefly with possible challenges and opportunities. It can be concluded that understanding the role of nanomedicine in tumor treatment is significant, and therefore, the modern progressions in this arena is essential to be considered for a prosperous today and an affluent future of tumor patients.

Nanocarriers for cancer nano-immunotherapy

The host immune system possesses an intrinsic ability to target and kill cancer cells in a specific and adaptable manner that can be further enhanced by cancer immunotherapy, which aims to train the immune system to boost the antitumor immune response. Several different categories of cancer immunotherapy have emerged as new standard cancer therapies in the clinic, including cancer vaccines, immune checkpoint inhibitors, adoptive T cell therapy, and oncolytic virus therapy. Despite the remarkable survival benefit for a subset of patients, the low response rate and immunotoxicity remain the major challenges for current cancer immunotherapy. Over the last few decades, nanomedicine has been intensively investigated with great enthusiasm, leading to marked advancements in nanoparticle platforms and nanoengineering technology. Advances in nanomedicine and immunotherapy have also led to the emergence of a nascent research field of nano-immunotherapy, which aims to realize the full therapeutic potential of immunotherapy with the aid of nanomedicine. In particular, nanocarriers present an exciting opportunity in immuno-oncology to boost the activity, increase specificity, decrease toxicity, and sustain the antitumor efficacy of immunological agents by potentiating immunostimulatory activity and favorably modulating pharmacological properties. This review discusses the potential of nanocarriers for cancer immunotherapy and introduces preclinical studies designed to improve clinical cancer immunotherapy modalities using nanocarrier-based engineering approaches. It also discusses the potential of nanocarriers to address the challenges currently faced by immuno-oncology as well as the challenges for their translation to clinical applications.

The Evolution and Recent Trends in Acoustic Targeting of Encapsulated Drugs to Solid Tumors: Strategies beyond Sonoporation

Despite recent advancements in ultrasound-mediated drug delivery and the remarkable success observed in pre-clinical studies, no delivery platform utilizing ultrasound contrast agents has yet received FDA approval. The sonoporation effect was a game-changing discovery with a promising future in clinical settings. Various clinical trials are underway to assess sonoporation's efficacy in treating solid tumors; however, there are disagreements on its applicability to the broader population due to long-term safety issues. In this review, we first discuss how acoustic targeting of drugs gained importance in cancer pharmaceutics. Then, we discuss ultrasound-targeting strategies that have been less explored yet hold a promising future. We aim to shed light on recent innovations in ultrasound-based drug delivery including newer designs of ultrasound-sensitive particles specifically tailored for pharmaceutical usage.

Aptamer-based rapid diagnosis for point-of-care application

Aptasensors have attracted considerable interest and widespread application in point-of-care testing worldwide. One of the biggest challenges of a point-of-care (POC) is the reduction of treatment time compared to central facilities that diagnose and monitor the applications. Over the past decades, biosensors have been introduced that offer more reliable, cost-effective, and accurate detection methods. Aptamer-based biosensors have unprecedented advantages over biosensors that use natural receptors such as antibodies and enzymes. In the current epidemic, point-of-care testing (POCT) is advantageous because it is easy to use, more accessible, faster to detect, and has high accuracy and sensitivity, reducing the burden of testing on healthcare systems. POCT is beneficial for daily epidemic control as well as early detection and treatment. This review provides detailed information on the various design strategies and virus detection methods using aptamer-based sensors. In addition, we discussed the importance of different aptamers and their detection principles. Aptasensors with higher sensitivity, specificity, and flexibility are critically discussed to establish simple, cost-effective, and rapid detection methods. POC-based aptasensors' diagnostic applications are classified and summarised based on infectious and infectious diseases. Finally, the design factors to be considered are outlined to meet the future of rapid POC-based sensors.

Advances in image-guided drug delivery for antibacterial therapy

The emergence of antibiotic-resistant bacterial strains is seriously endangering the global healthcare system. There is an urgent need for combining imaging with therapies to realize the real-time monitoring of pathological condition and treatment progress. It also provides guidance on exploring new medicines and enhance treatment strategies to overcome the antibiotic resistance of existing conventional antibiotics. In this review, we provide a thorough overview of the most advanced image-guided approaches for bacterial diagnosis (e.g., computed tomography imaging, magnetic resonance imaging, photoacoustic imaging, ultrasound imaging, fluorescence imaging, positron emission tomography, single photon emission computed tomography imaging, and multiple imaging), and therapies (e.g., photothermal therapy, photodynamic therapy, chemodynamic therapy, sonodynamic therapy, immunotherapy, and multiple therapies). This review focuses on how to design and fabricate photo-responsive materials for improved image-guided bacterial theranostics applications. We present a potential application of different image-guided modalities for both bacterial diagnosis and therapies with representative examples. Finally, we highlighted the current challenges and future perspectives image-guided approaches for future clinical translation of nano-theranostics in bacterial infections therapies. We envision that this review will provide for future development in image-guided systems for bacterial theranostics applications.

Recent developments in silver nanoparticles utilized for cancer treatment and diagnosis: a patent review

Nanotheranostics is a young but rapidly expanding science that incorporates elements of therapy and diagnostics in a unique and miniscule area of research. The potential to combine diagnostic and therapeutic abilities inside a complete unit opens up interesting possibilities for innovative biomedical research. Silver-based nanoparticles, for instance, are widely utilized as pharmacological and biomedical imaging molecules, and hence offer a lot of potential for the development of versatile targeted therapy compositions. These nanoparticles have been used for cancer diagnosis and cancer treatments recently. We evaluate major innovations based on silver nanotheranostics technologies in this review paper, with an emphasis on cancer treatment implications. The present review covers papers, from 2010 to 2020.

Exploration of Site-Specific Drug Targeting-A Review on EPR-, Stimuli-, Chemical-, and Receptor-Based Approaches as Potential Drug Targeting Methods in Cancer Treatment

Cancer has been one of the most dominant causes of mortality globally over the last few decades. In cancer treatment, the selective targeting of tumor cells is indispensable, making it a better replacement for conventional chemotherapies by diminishing their adverse side effects. While designing a drug to be delivered selectively in the target organ, the drug development scientists should focus on various factors such as the type of cancer they are dealing with according to which drug, targeting moieties, and pharmaceutical carriers should be targeted. All published articles have been collected regarding cancer and drug-targeting approaches from well reputed databases including MEDLINE, Embase, Cochrane Library, CENTRAL and ClinicalTrials.gov, Science Direct, PubMed, Scopus, Wiley, and Springer. The articles published between January 2010 and December 2020 were considered. Due to the existence of various mechanisms, it is challenging to choose which one is appropriate for a specific case. Moreover, a combination of more than one approach is often utilized to achieve optimal drug effects. In this review, we have summarized and highlighted central mechanisms of how the targeted drug delivery system works in the specific diseased microenvironment, along with the strategies to make an approach more effective. We have also included some pictorial illustrations to have a precise idea about different types of drug targeting. The core contribution of this work includes providing a cancer drug development scientist with a broad preliminary idea to choose the appropriate approach among the various targeted drug delivery mechanisms. Also, the study will contribute to improving anticancer treatment approaches by providing a pathway for lesser side effects observed in conventional chemotherapeutic techniques.

A multifunctional nanotheranostic agent potentiates erlotinib to EGFR wild-type non-small cell lung cancer

Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKI), such as Erlotinib, have demonstrated remarkable efficacy in the treatment of non-small cell lung cancer (NSCLC) patients with mutated EGFR. However, the efficacy of EGFR-TKIs in wild-type (wt) EGFR tumours has been shown to be marginal. Methods that can sensitize Erlotinib to EGFR wild-type NSCLC remain rare. Herein, we developed a multifunctional superparamagnetic nanotheranostic agent as a novel strategy to potentiate Erlotinib to EGFR-wt NSCLCs. Our results demonstrate that the nanoparticles can co-escort Erlotinib and a vascular epithermal growth factor (VEGF) inhibitor, Bevacizumab (Bev), to EGFR-wt tumours. The nanotheranostic agent exhibits remarkable effects as an inhibitor of EGFR-wt tumour growth. Moreover, Bev normalizes the tumour embedded vessels, further promoting the therapeutic efficacy of Erlotinib. In addition, the tumour engagement of the nanoparticles and the vascular normalization could be tracked by magnetic resonance imaging (MRI). Collectively, our study, for the first time, demonstrated that elaborated nanoparticles could be employed as a robust tool to potentiate Erlotinib to EGFR-wt NSCLC, paving the way for imaging-guided nanotheranostics for refractory NSCLCs expressing EGFR wild-type genes.

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A Erlotinib-based nanoagent shows remarkable efficacy to inhibit EGFR-wt NSCLCs.

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Erlotinib and Bevacizumab show synergistic effects in inhibit EGFR-wt NSCLC.

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MRI was used to track the tumour engagement of the Erlotinib-based nanoagent.

Tumor Stimulus-Responsive Biodegradable Diblock Copolymer Conjugates as Efficient Anti-Cancer Nanomedicines

Biodegradable nanomedicines are widely studied as candidates for the effective treatment of various cancerous diseases. Here, we present the design, synthesis and evaluation of biodegradable polymer-based nanomedicines tailored for tumor-associated stimuli-sensitive drug release and polymer system degradation. Diblock polymer systems were developed, which enabled the release of the carrier drug, pirarubicin, via a pH-sensitive spacer allowing for the restoration of the drug cytotoxicity solely in the tumor tissue. Moreover, the tailored design enables the matrix-metalloproteinases- or reduction-driven degradation of the polymer system into the polymer chains excretable from the body by glomerular filtration. Diblock nanomedicines take advantage of an enhanced EPR effect during the initial phase of nanomedicine pharmacokinetics and should be easily removed from the body after tumor microenvironment-associated biodegradation after fulfilling their role as a drug carrier. In parallel with the similar release profiles of diblock nanomedicine to linear polymer conjugates, these diblock polymer conjugates showed a comparable in vitro cytotoxicity, intracellular uptake, and intratumor penetration properties. More importantly, the diblock nanomedicines showed a remarkable in vivo anti-tumor efficacy, which was far more superior than conventional linear polymer conjugates. These findings suggested the advanced potential of diblock polymer conjugates for anticancer polymer therapeutics.

Recent advances in herbal combination nanomedicine for cancer: delivery technology and therapeutic outcomes

Introduction: The use of herbal compounds in cancer therapy has great potential to promote the efficacy of current cancer therapeutic strategies. Herbal compounds were successfully reported to enhance tumor cells sensitization to the action of chemo-, hormonal- and gene-therapeutic agents via different mechanisms. Herbal ingredients can affect different signaling pathways, reduce the toxic side effects or inhibit the efflux of anticancer drugs.Areas covered: This review will discuss the delivery of herbal compounds with other cancer treatments such as hormonal, small molecule inhibitors and inorganic hybrids to tumor cells. An overview of physicochemical properties of herbal components that require intelligent design of combo-nanomedicines for efficient co-delivery of those herbal-derived and other anticancer agents was discussed. Nanocarriers provide various benefits to overcome the shortcomings of the encapsulated herbal compounds including improved solubility, increased stability and enhanced tumor targeting. Different nanocarrier systems were the focus of this review.Expert opinion: Multifunctional nanocarrier systems encapsulating herbal and different anticancer drugs showed to be a wonderful approach in the treatment of cancer enabling the co-delivery of anticancer drugs with versatile modes of action in an accurate manner in an attempt to enhance the efficacy, benefit from the synergism between the drugs as well as to minimize the development of multi-drug resistance. The main challenge point is the early detection and management of any developed adverse effect.

Theranostic Applications of Nanomaterials in the Field of Cardiovascular Diseases

A large percentage of people are being exposed to mortality due to cardiovascular diseases. Convention approaches have not provided satisfactory outcomes in the management of these diseases. To overcome the limitations of conventional approaches, nanomaterials like nanoparticles, nanotubes, micelles, lipid based nanocarriers, dendrimers, carbon based nano-formulations represent the new aspect of diagnosis and treatment of cardiovascular diseases. The unique inherent properties of the nanomaterials are the major reasons for their rapidly growing demand in the field of medicine. Profound knowledge in the field of nanotechnology and biomedicine is needed for the notable translation of nanomaterials into theranostic cardiovascular applications. In this review, the authors have summarized different nanomaterials which are being extensively used to diagnose and treat the diseases such as coronary heart disease, myocardial infarction, atherosclerosis, stroke and thrombosis.

Graphene quantum dot formulation for cancer imaging and redox-based drug delivery

This work develops a new multifunctional biocompatible anticancer nanoformulation to provide targeted image-guided cancer-selective therapeutics. It consists of three active covalently bound components: (1) biocompatible nitrogen-doped graphene quantum dots (GQDs) as a multifunctional delivery and imaging platform, (2) hyaluronic acid (HA) unit targeted to the CD44 receptors on a variety of cancer cells, and (3) oxidative stress-based cancer-selective ferrocene (Fc) therapeutic. The biocompatible GQD platform synthesized from glucosamine exhibits high-yield intrinsic fluorescence. It is utilized for tracking Fc-GQD-HA formulation in vitro indicating internalization enhancement in HeLa cells targeted by the HA over non-cancer HEK-293 cells not overexpressing CD44 receptor. Fc-GQD-HA, non-toxic at 1 mg/mL to HEK-293 cells, induces cytotoxic response in HeLa enhanced over time, while therapeutic ROS generation by Fc-GQD-HA is ~3 times greater than that of Fc alone. This outlines the targeted delivery, imaging, and cancer-specific treatment capabilities of the new Fc-GQD-HA formulation enabling desired cancer-focused nanotherapeutic approach.

Harnessing Endogenous Stimuli for Responsive Materials in Theranostics

Materials that respond to endogenous stimuli are being leveraged to enhance spatiotemporal control in a range of biomedical applications from drug delivery to diagnostic tools. The design of materials that undergo morphological or chemical changes in response to specific biological cues or pathologies will be an important area of research for improving efficacies of existing therapies and imaging agents, while also being promising for developing personalized theranostic systems. Internal stimuli-responsive systems can be engineered across length scales from nanometers to macroscopic and can respond to endogenous signals such as enzymes, pH, glucose, ATP, hypoxia, redox signals, and nucleic acids by incorporating synthetic bio-inspired moieties or natural building blocks. This Review will summarize response mechanisms and fabrication strategies used in internal stimuli-responsive materials with a focus on drug delivery and imaging for a broad range of pathologies, including cancer, diabetes, vascular disorders, inflammation, and microbial infections. We will also discuss observed challenges, future research directions, and clinical translation aspects of these responsive materials.

Catalytic parameters and thermal stability of chondroitinase ABCI on red porous silicon nanoparticles

The bacterial enzyme chondroitinase ABC, which digests extracellular chondroitin sulfate proteoglycans, has been shown to enhance axonal regeneration. However, the utilization of this enzyme as therapeutics is notably restricted due to its thermal instability. Therefore, red luminescent porous silicon that hold promise for potential applications in biological/medical imaging was used as a carrying matrix for chondroitinase with the aim of enhancing its stability. Porous Si nanoparticles were prepared by electrochemical etching of silicon wafers in ethanolic HF solution. The size of nanoparticles (210 nm) and the mean pore diameter (8 -20 nm) were determined using dynamic light scattering and scanning electron microscopy. Purified chondroitinase was then incorporated into the silicon pores. Results revealed similar K_m and lower V_max value for the immobilized enzyme when compared with the free enzyme. The immobilized chondroitinase exhibited about a 4 fold increase in stability at 37 °C after 50 min. It is likely possible that, the enzyme was protected inside the pores resulted in higher stability. Moreover, porous silicon was seen to be capable of holding the chondroitinase for repeated cyclic tests for three times. The cell viability assay exhibited no significant cytotoxicity for Psi-chondroitinase up to 24 h.

Further Development of Near-Infrared Mediated Quantum Dots and Paclitaxel Co-loaded Nanostructured Lipid Carrier System for Cancer Theragnostic

Of colloidal systems, ceteris paribus, nanostructured lipid carriers are second to none in offering a single-unit platform for multifunctional benefits. Quantum dots are known to possess unique properties that make them ideal for imaging purpose and that they may be used for cancer detection. For several decades, paclitaxel has been the most effective drug against a wide range of solid tumours. Theragnostic nanomedicine provides a platform to monitor, evaluate, and individualize treatment in real time. Evaluation of cancer treatment outcome at an early stage therapy is key to increase survival prospects of a patient. Previously, a novel co-loaded nanostructured lipid carriers’ theragnostic system for parenteral administration was developed. The aim of this study was to further investigate the co-loaded nanostructured lipid carriers in order to provide interpretation necessary for preclinical elucidation of the formulation, in part. The co-loaded nanostructured lipid carriers were prepared by oil/water emulsification-solvent evaporation technique. In this study, stability and co-loaded nanostructured lipid carriers’ internalization by MCF 7 and HepG2 cells were investigated. The co-loaded nanostructured lipid carriers was stable at 4°C for 1 month. The formulation was successfully internalized by MCF-7 and HepG2 cells. Nevertheless, the co-loaded nanostructured lipid carrier was more apt for MCF-7 cells. This finding affirms the formulation to be the most appropriate for breast cancer treatment. In addition, if taken correctly by a patient for a month, the formulation would give true reflection of the contents’ amounts, the factor paramount to appropriate changes in treatment protocol. It can therefore safely be concluded that the co-loaded nanostructured lipid carrier formulation may be potentially an effective theragnostic translational system.

When rare earth meets carbon nanodots: mechanisms, applications and outlook

Rare earth (RE) elements are widely used in the luminescence and magnetic fields by virtue of their abundant 4f electron configurations. However, the overall performance and aqueous stability of single-component RE materials need to be urgently improved to satisfy the requirements for multifunctional applications. Carbon nanodots (CNDs) are excellent nanocarriers with abundant functional surface groups, excellent hydrophilicity, unique photoluminescence (PL) and tunable features. Accordingly, RE-CND hybrids combine the merits of both RE and CNDs, which dramatically enhance their overall properties such as luminescent and magnetic-optical imaging performances, leading to highly promising practical applications in the future. Nevertheless, a comprehensive review focusing on the introduction and in-depth understanding of RE-CND hybrid materials has not been reported to date. This review endeavors to summarize the recent advances of RE-CNDs, including their interaction mechanisms, general synthetic strategies and applications in fluorescence, biosensing and multi-modal biomedical imaging. Finally, we present the current challenges and the possible application perspectives of newly developed RE-CND materials. We hope this review will inspire new design ideas and valuable references in this promising field in the future.

PEG-PLGA nanospheres loaded with nanoscintillators and photosensitizers for radiation-activated photodynamic therapy

Photodynamic Therapy (PDT) is an effective treatment modality for cancers, with Protoporphyrin IX (PPIX)-based PDT being the most widely used to treat cancers in patients. However, PDT is limited to superficial, thin (few mm in depth) lesions that can be accessed by visible wavelength light. Interstitial light-delivery strategies have been developed to treat deep-seated lesions (i.e. prostate cancer). The most promising of these are X-ray-induced scintillation nanoparticles, which have shown potential benefits for PDT of deep-seated tumors. Herein, the design and use of a new nanoscintillator-based radiation-activated PDT (radioPDT) system is investigated in the treatment of deep-seated tumors. Poly(ethylene glycol) methyl ether-block-poly(lactide-co-glycolide) (PEG-PLGA) nanospheres were loaded with a scintillator (LaF₃:Ce³⁺) and photosensitizer (PPIX) to effect radioPDT. UV-Vis spectroscopy and electron microscopy studies demonstrated efficient encapsulation of nanoscintillators and PPIX (>90% efficiency) into the PEG-PLGA nanospheres. The nanoparticles were uniform in size and approximately 100 nm in diameter. They were highly stable and functional for up to 24 h under physiological conditions and demonstrated slow release kinetics. In vitro and in vivo toxicity studies showed no appreciable drug toxicity to human skin fibroblast (GM38), prostate cancer cells (PC3), and to C57/BL mice. Cell uptake studies demonstrated accumulation of the nanoparticles in the cytoplasm of PC3 cells. When activated, fluorescent resonant energy transfer (FRET) was evident via fluorescent spectroscopy and singlet oxygen yield. Determination of stability revealed that the nanoparticles were stable for up to 4 weeks. The nanoparticle production was scaled-up with no change in properties. This nanoparticle represents a unique, optimally designed therapeutic and diagnostic agent (theranostic) agent for radioPDT with characteristics capable of potentially augmenting radiotherapy for deep-seated tumors and integrating into current cancer radiotherapy.

Conjugated Photosensitizers for Imaging and PDT in Cancer Research

Early cancer detection and perfect understanding of the disease are imperative toward efficient treatments. It is straightforward that, for choosing a specific cancer treatment methodology, diagnostic agents undertake a critical role. Imaging is an extremely intriguing tool since it assumes a follow up to treatments to survey the accomplishment of the treatment and to recognize any conceivable repeating injuries. It also permits analysis of the disease, as well as to pursue treatment and monitor the possible changes that happen on the tumor. Likewise, it allows screening the adequacy of treatment and visualizing the state of the tumor. Additionally, when the treatment is finished, observing the patient is imperative to evaluate the treatment methodology and adjust the treatment if necessary. The goal of this review is to present an overview of conjugated photosensitizers for imaging and therapy.

Doxorubicin-loaded fluorescent carbon dots with PEI passivation as a drug delivery system for cancer therapy

In this work, we reported a novel and effective cancer treatment strategy by fabricating carbon dot (CD)-polyethylenimine (PEI)-doxorubicin (DOX) antitumor drug complexes from a combination of PEI-passivated CDs (CD-PEI) and DOX. CD-PEI was synthesized by the one-step microwave hydrothermal carbonization of a mixture of glycerol and PEI-25k, enabling simultaneous synthesis and surface passivation of CDs. DOX was loaded onto CD-PEI by electrostatic interactions. The results show that this system not only improves selective drug release but also prolongs the drug release time and improves the killing effect on tumors. Compared with free DOX, the CD-PEI-DOX complex has a stronger killing effect on liver cancer cells (MHCC-97L and Hep3B cells) but a very low killing effect on normal liver cells (L02). Studies have also confirmed that compared with DOX alone, CD-PEI-DOX nanoparticles can effectively inhibit tumors because of the larger amount of drugs localized in tumor cells and the higher apoptosis rate of MHCC-97L cells. In vivo experiments confirmed that CD-PEI-DOX has a stronger inhibitory effect on tumor growth, indicating that CD-PEI-DOX nanomedicine has inhibitory effects on tumors.

A brief review on solid lipid nanoparticles: part and parcel of contemporary drug delivery systems

Drug delivery technology has a wide spectrum, which is continuously being upgraded at a stupendous speed. Different fabricated nanoparticles and drugs possessing low solubility and poor pharmacokinetic profiles are the two major substances extensively delivered to target sites. Among the colloidal carriers, nanolipid dispersions (liposomes, deformable liposomes, virosomes, ethosomes, and solid lipid nanoparticles) are ideal delivery systems with the advantages of biodegradation and nontoxicity. Among them, nano-structured lipid carriers and solid lipid nanoparticles (SLNs) are dominant, which can be modified to exhibit various advantages, compared to liposomes and polymeric nanoparticles. Nano-structured lipid carriers and SLNs are non-biotoxic since they are biodegradable. Besides, they are highly stable. Their (nano-structured lipid carriers and SLNs) morphology, structural characteristics, ingredients used for preparation, techniques for their production, and characterization using various methods are discussed in this review. Also, although nano-structured lipid carriers and SLNs are based on lipids and surfactants, the effect of these two matrixes to build excipients is also discussed together with their pharmacological significance with novel theranostic approaches, stability and storage.

Trigger-responsive engineered-nanocarriers and image-guided theranostics for rheumatoid arthritis

Rheumatoid Arthritis (RA), one of the leading causes of disability due to progressive autoimmune destruction of synovial joints, affects ∼1% of the global population. Standard therapy helps in reducing inflammation and delaying the progression of RA but is limited by non-responsiveness on long-term use and several side-effects. The conventional nanocarriers (CNCs), to some extent, minimize toxicity associated with free drug administration while improving the therapeutic efficacy. However, the uncontrolled release of the encapsulated drug even at off-targeted organs limits the application of CNCs. To overcome these challenges, trigger-responsive engineered nanocarriers (ENCs) have been recently explored for RA treatment. Unlike CNCs, ENCs enable precise control over on-demand drug release due to endogenous triggers in arthritic paws like pH, enzyme level, oxidative stress, or exogenously applied triggers like near-infrared light, magnetic field, ultrasonic waves, etc. As the trigger is selectively applied to the inflamed joint, it potentially reduces toxicity at off-target locations. Moreover, ENCs have been strategically coupled with imaging probe(s) for simultaneous monitoring of ENCs inside the body and facilitate an 'image-guided-co-trigger' for site-specific action in arthritic paws. In this review, the progress made in recently emerging 'trigger-responsive' and 'image-guided theranostics' ENCs for RA treatment has been explored with emphasis on the design strategies, mechanism, current status, challenges, and translational perspectives.

Photonic Carbon Dots as an Emerging Nanoagent for Biomedical and Healthcare Applications

As a class of carbon-based nanomaterials, carbon dots (CDs) have attracted enormous attention because of their tunable optical and physicochemical properties, such as absorptivity and photoluminescence from ultraviolet to near-infrared, high photostability, biocompatibility, and aqueous dispersity. These characteristics make CDs a promising alternative photonic nanoagent to conventional fluorophores in disease diagnosis, treatment, and healthcare managements. This review describes the fundamental photophysical properties of CDs and highlights their recent applications to bioimaging, photomedicine (e.g., photodynamic/photothermal therapies), biosensors, and healthcare devices. We discuss current challenges and future prospects of photonic CDs to give an insight into developing vibrant fields of CD-based biomedicine and healthcare.

Luminescent anticancer Ru(II)-arenebipyridine and phenanthroline complexes: Synthesis, characterization, DFT studies, biological interactions and cellular imaging application

A series of ruthenium(II)-arene complexes of several bipyridine and phenanthroline derivatives have been synthesized by employing a green and efficient protocol involving water as a solvent under sonication. The structures of all the complexes were elucidated by the spectroscopic analysis. The geometry of the chlorido and PTA (1,3,5-Triaza-7-phosphaadamantane) complexes were further confirmed by DFT and single crystal XRD. The stability study in various solvents, specifically in the intracellular one was conducted. Most of the compounds exhibited significant potency and selectivity against MCF7 and HeLa cell lines with respect to normal HEK-293 cells compared to cisplatin and RAPTA-C (Ruthenium(II)-arene PTA complex). Complex [(η6-hexamethylbenzene)RuCl(κ2-N,N-4,4'-di-n-nonyl-2,2'-bpy)]Cl (3e) presented best anticancer profiles against all the human cancer cells. Interestingly, few complexes turned up to be highly fluorescent depicted by the quantum yield values. Remarkably, [(η6-p-cymene)RuCl(κ2-N,N-bpy)]Cl (3i) was identified as most significant anticancer theranostic agent interms of potency, selectivity and fluorescence quantum yield. This complex also represented itself as significant cellular imaging agent in live U-87 MG cells which was monitored by confocal microscope. Absorption and emission spectral studies of bypyridine and phenanthroline complex series revealed that the complexes interacted with calf thymus DNA through groove binding as well as intercalative mode. In addition to this, strong binding efficacy of these scaffolds wih BSA (Bovin Serum Albumin) also enhanced their transportation property inside the cells.

Nanotheranostic Applications for Detection and Targeting Neurodegenerative Diseases

Nanotechnology utilizes engineered materials and devices which function with biological systems at the molecular level and could transform the management of neurodegenerative diseases (NDs) by provoking, reacting to, and intermingling with target sites to stimulate physiological responses while minimizing side effects. Blood-brain barrier (BBB) protects the brain from harmful agents, and transporting drugs across the BBB is a major challenge for diagnosis, targeting, and treatment of NDs. The BBB provides severe limitations for diagnosis and treatment of Alzheimer's disease (AD), Parkinson's disease (PD), and various other neurological diseases. Conventional drug delivery systems generally fail to cross the BBB, thus are inefficient in treatment. Although gradual development through research is ensuring the progress of nanotheranostic approaches from animal to human modeling, aspects of translational applicability and safety are a key concern. This demands a deep understanding of the interaction of body systems with nanomaterials. There are various plant-based nanobioactive compounds which are reported to have applicability in the diagnosis and treatment of these NDs. This review article provides an overview of applications of nanotheranostics in AD and PD. The review also discusses nano-enabled drug delivery systems and their current and potential applications for the treatment of various NDs.

Indocyanine Green Loaded Polymeric Nanoparticles: Physicochemical Characterization and Interaction Studies with Caco-2 Cell Line by Light and Transmission Electron Microscopy

Biomedical applications of nanoparticles (NPs) have reached an increasing development in recent years. Recently, we demonstrated that newly synthesized poly (ethyl 2-cyanoacrylate) nanoparticles (PECA-NPs) are possible antitumor agents due to their cytotoxicity for cancer cells. Indocyanine green (ICG), an amphiphilic tricarbocyanine fluorescent dye, is widely used for the detection of tumoral extension in different organs during clinical surgery. Moreover, this fluorescent agent is unstable and it has a rapid clearance in physiological conditions in vivo. In this study, ICG was charged in PECA-NPs to improve its aqueous stability and make easier its use for the identification of tumor cells. Microscopic and ultrastructural aspects concerning the related in vitro interactions between ICG-loaded NPs and tumor cell culture were investigated. Obtained results showed an effective stabilization of ICG; furthermore, color inclusions inside the cells treated with ICG-loaded NPs demonstrated the internalization of NPs with associated ICG. Transmission electron microscopy (TEM) analysis demonstrated the cytoplasmic presence of coated vesicles (Ø ≤ 100 nm), hypothesizing their involvement in the mechanism of endocytosis. Therefore, ICG-loaded NPs could be proposed as agents for tumor diagnosis, hypothesizing also in the future a specific therapeutic treatment.

Imaging-assisted anticancer nanotherapy

Cancer nanomedicines are submicrometer-sized formulations designed to improve the biodistribution of anticancer drugs, resulting in less off-target localization, altered toxicity profiles, improved target site accumulation and enhanced efficacy. Together, these beneficial features have resulted in the regulatory approval of about a dozen nanomedicines for the treatment of solid and hematological malignancies. In recent years, significant progress has been made in combining nanomedicines with imaging, to better understand key aspects of the tumor-targeted drug delivery process, and to address the high inter- and intra-individual heterogeneity in the Enhanced Permeability and Retention (EPR) effect. Strategies explored in this regard have included the use of traditional imaging techniques, companion diagnostics and nanotheranostics. Preclinically, integrating imaging in nanomedicine and drug delivery research has enabled the non-invasive and quantitative assessment of nanocarrier biodistribution, target site accumulation and (triggered) drug release. Clinically, imaging has been emerging as a promising tool for patient stratification, which is urgently needed to improve the translation of cancer nanomedicines. We here summarize recent progress in imaging-assisted anticancer nanotherapy and we discuss future strategies to improve the performance of cancer nanomedicines in patients.

Titanate Nanotubes Engineered with Gold Nanoparticles and Docetaxel to Enhance Radiotherapy on Xenografted Prostate Tumors

Nanohybrids based on titanate nanotubes (TiONts) were developed to fight prostate cancer by intratumoral (IT) injection, and particular attention was paid to their step-by-step synthesis. TiONts were synthesized by a hydrothermal process. To develop the custom-engineered nanohybrids, the surface of TiONts was coated beforehand with a siloxane (APTES), and coupled with both dithiolated diethylenetriaminepentaacetic acid-modified gold nanoparticles (Au@DTDTPA NPs) and a heterobifunctional polymer (PEG₃₀₀₀) to significantly improve suspension stability and biocompatibility of TiONts for targeted biomedical applications. The pre-functionalized surface of this scaffold had reactive sites to graft therapeutic agents, such as docetaxel (DTX). This novel combination, aimed at retaining the AuNPs inside the tumor via TiONts, was able to enhance the radiation effect. Nanohybrids have been extensively characterized and were detectable by SPECT/CT imaging through grafted Au@DTDTPA NPs, radiolabeled with ¹¹¹In. In vitro results showed that TiONts-AuNPs-PEG₃₀₀₀-DTX had a substantial cytotoxic activity on human PC-3 prostate adenocarcinoma cells, unlike initial nanohybrids without DTX (Au@DTDTPA NPs and TiONts-AuNPs-PEG₃₀₀₀). Biodistribution studies demonstrated that these novel nanocarriers, consisting of AuNP- and DTX-grafted TiONts, were retained within the tumor for at least 20 days on mice PC-3 xenografted tumors after IT injection, delaying tumor growth upon irradiation.

Theranostic Nanomedicine for Malignant Gliomas

Brain tumors mainly originate from glial cells and are classified as gliomas. Malignant gliomas represent an incurable disease; indeed, after surgery and chemotherapy, recurrence appears within a few months, and mortality has remained high in the last decades. This is mainly due to the heterogeneity of malignant gliomas, indicating that a single therapy is not effective for all patients. In this regard, the advent of theranostic nanomedicine, a combination of imaging and therapeutic agents, represents a strategic tool for the management of malignant brain tumors, allowing for the detection of therapies that are specific to the single patient and avoiding overdosing the non-responders. Here, recent theranostic nanomedicine approaches for glioma therapy are described.

The Synergism of Platinum-Gold Bimetallic Nanoconjugates Enhances 5-Fluorouracil Delivery In Vitro

Nanoparticle application has significantly impacted the field of medicine. The need to develop novel drugs with higher therapeutic potential has stimulated the development of innovative delivery strategies to mitigate the potent side effects associated with known chemotherapeutic drugs. This paper describes the synthesis of platinum-gold bimetallic nanoparticles (PtAuBNps), their functionalisation with chitosan, and entrapment of the anticancer drug 5-fluorouracil (5-FU). All PtAuBNps and their drug nanocomposites were physico-chemically characterised, displaying desirable properties with regards to shape, size (<120 nm) and colloidal stability. 5-FU binding and loading capacities in PtAuBNps were found to be 90.17% and 22.56%, respectively. In vitro cytotoxicity profiles determined using the MTT and SRB assays reflected up to 65% cell death in the MCF-7, HepG2 and Caco-2 cell lines. These nanocomposites exhibited excellent physiochemical attributes, high specificity towards cancer cells, with a pH-sensitive drug release in a simulated acidic tumour microenvironment through zero-order release kinetics. In addition, they possessed the potential to traverse the mucosal lining facilitating oral drug administration. Overall, 5-FU encapsulation improved the bioavailability of the drug in cancer cells, with the promise of enhancing its therapeutic effect, biocompatibility and safety. These positive results highlight PtAuBNps as promising in vitro delivery systems and merits future in vivo research.

Pegylated magnetic mesoporous silica nanoparticles decorated with AS1411 Aptamer as a targeting delivery system for cytotoxic agents

Fulfilling the purpose of developing a NP with theragnostic capabilities, the current study describes the synthesis of an aptamer-functionalized PEG-coated SPION/mesoporous silica core-shell nanoparticle for concurrent cancer targeted therapy and magnetic resonance imaging. SPIONs were synthesized according to a thermal decomposition method and served as cores for SPION/mesoporous silica core/shell nanoparticles (MMSNs). Doxorubicin was then successfully loaded in MMSNs which were then coated with di-carboxylic acid functionalized polyethylene glycol (PEG-MMSNs). AS1411 aptamers were at the end covalently attached to NPs (APT-PEG-MMSNs). The mean diameter of synthesized NPs was about 89 nm and doxorubicin encapsulation efficacy was ≈67.47%. Results of MTT based cell cytotoxicity assay demonstrated a significantly higher toxicity profile for APT-PEG-MMSNs against MCF7 cells compared to non-decorated MMSNs, while no significant differences were spotted against NIH-3T3 cells. Meanwhile, formation of protein corona around APT-PEG-MMSNs in biological medium significantly attenuated observed cytotoxicity against MCF7 cell line. Examining NPs uptake by MCF7 cells using confocal laser scanning microscopy also confirmed superiority of APT-PEG-MMSNs over PEG-MMSNs. Finally, APT decorated NPs induced highest signal intensity reduction in T₂-weighted images during in vitro MRI assay. In conclusion, developed NPs may serve as promising multifunctional vehicles for simultaneous cancer targeted therapy and MRI imaging.

Nanoconjugation and Encapsulation Strategies for Improving Drug Delivery and Therapeutic Efficacy of Poorly Water-Soluble Drugs

Nanoconjugations have been demonstrated to be a dominant strategy for drug delivery and biomedical applications. In this review, we intend to describe several strategies for drug formulation, especially to improve the bioavailability of poorly water-soluble molecules for future application in the therapy of numerous diseases. The context of current studies will give readers an overview of the conjugation strategies for fabricating nanoparticles, which have expanded from conjugated materials to the surface conjugation of nanovehicles. Moreover, nanoconjugates for theranostics are also discussed and highlighted. Overall, these state-of-the-art conjugation methods and these techniques and applications for nanoparticulate systems of poorly water-soluble drugs will inspire scientists to explore and discover more productive techniques and methodologies for drug development.