Activatable cell penetrating peptides linked to nanoparticles as dual probes for in vivo fluorescence and MR imaging of proteases

Tumor agnostic ultrasmall nanoprobes for fluorescence-guided surgical resection in peritoneal metastasis

PURPOSE

Surgical excision of metastases is the only curative treatment strategy in peritoneal carcinomatosis management, and the completeness of tumor resection determines the success of the surgery. Tumor-specific fluorescence-guided probes can improve the outcomes of cytoreductive surgery and thereby prognosis. This study aimed to develop and evaluate the feasibility of fluorescently labeled ultrasmall porous silica nanoparticles (UPSN) for image-guided resection of peritoneally disseminated tumors of different origins.

METHODS

Ultrasmall fluorescent nanoprobes were synthesized and characterized for their physicochemical properties and stability. Tumor-specific uptake and biodistribution profiles were evaluated in syngeneic CT26 colorectal and KPC-689 pancreatic cancer murine models. The practicability of real-time optical UPSN-guided resection was examined in the CT26 colorectal cancer model using a surgical stereomicroscope. Quantitative measurements of tumor sensitivity and specificity were performed. Histopathological examination validated in vivo findings about tumor-specific accumulation and safety of ultrasmall fluorescent probes.

RESULTS

As-synthesized UPSNs were successfully surface modified with Cy5 or Cy3 dyes maintaining sub-15 nm size and near neutral charge which is beneficial for optimized in vivo pharmacokinetics. UPSN-Cy5 demonstrated high tumor-specific uptake and favorable biodistribution profiles in peritoneal metastasis models of CT26 and KPC tumors. Dye-conjugated UPSN enabled resection of microscopic lesions and achieved a higher tumor-to-background ratios in comparison to FDA-approved indocyanine green (ICG) dye in both models. Microscopic evaluation showed tumor localization and off-target safety profile of the UPSN-Cy5.

CONCLUSION

Ultrasmall fluorescent probes were effective in surgical resection of peritoneal metastases with high sensitivity and specificity, thus emerging as promising tumor agnostic agents for image-guided cancer surgery.

Virus-like particle encapsulation of functional proteins: advances and applications

Proteins face several challenges in biomedicine, including issues with antibody production, degradation by proteases, rapid clearance by the kidneys, and short half-lives. To address these problems, various nano delivery systems have been developed, with virus-like particles (VLPs) emerging as a leading solution. VLPs, which are self-assembled protein complexes, offer effective encapsulation and transport of proteins. They provide enhanced stability, extended circulation time, preserved biological activity, improved targeting for therapies or imaging, and reduced side effects due to minimized systemic exposure. This review explores various methods for encapsulating proteins within VLPs. It assesses the benefits and limitations of each method and their applications in imaging, therapeutic enzyme delivery, vaccines, immunotherapy, nanoreactors, and biosensors. Future advancements in VLPs will depend on improving packaging methods, controlling protein loading, optimizing assembly techniques, and enhancing capsid design. The review also discusses current challenges and proposes solutions to advance the use of VLPs in various applications.

Cell-Penetrating Peptide-Mediated Biomolecule Transportation in Artificial Lipid Vesicles and Living Cells

Signal transduction and homeostasis are regulated by complex protein interactions in the intracellular environment. Therefore, the transportation of impermeable macromolecules (nucleic acids, proteins, and drugs) that control protein interactions is essential for modulating cell functions and therapeutic applications. However, macromolecule transportation across the cell membrane is not easy because the cell membrane separates the intra/extracellular environments, and the types of molecular transportation are regulated by membrane proteins. Cell-penetrating peptides (CPPs) are expected to be carriers for molecular transport. CPPs can transport macromolecules into cells through endocytosis and direct translocation. The transport mechanism remains largely unclear owing to several possibilities. In this review, we describe the methods for investigating CPP conformation, translocation, and cargo transportation using artificial membranes. We also investigated biomolecular transport across living cell membranes via CPPs. Subsequently, we show not only the biochemical applications but also the synthetic biological applications of CPPs. Finally, recent progress in biomolecule and nanoparticle transportation via CPPs into specific tissues is described from the viewpoint of drug delivery. This review provides the opportunity to discuss the mechanism of biomolecule transportation through these two platforms.

HER2-targeted, enzyme-activated liposomes show superior in vivo efficacy in an ovarian cancer model

Liposomes carrying chemotherapeutic drugs can accumulate passively in solid tumors at high levels. However, additional targeting of the liposomes towards e.g. receptors expressed on cancer cells may improve their interaction and therapeutic properties. In this study, we designed a liposomal delivery system, which utilizes the intrinsic characteristics of HER2-positive tumors to ensure efficient delivery of oxaliplatin to the cancer cells. On the liposome surface, trastuzumab, an antibody specific to the HER2 receptor, was shown to facilitate internalization by the cancer cells. A polyethylene glycol (PEG) layer on the liposome surface provides protection from mononuclear phagocyte system uptake. To optimize the interaction between liposomes and cancer cells, a protease-sensitive cleavable peptide linker was inserted at the base of each PEG. The PEG layer is then cleaved off by intra- and extracellular matrix metalloproteinases (MMPs) upon accumulation in the tumor. Our data demonstrate that the removal of PEG significantly destabilizes the liposomes and leads to substantial oxaliplatin release. The proposed beneficial effect of combining antibody-mediated internalization with MMP sensitivity was confirmed in a series of in vivo studies using ovarian cancer xenograft models. The results demonstrated that HER2-targeted MMP-sensitive liposomes have superior anticancer activity compared to non-targeted and non-cleavable liposomes.

Supramolecular cage-mediated cargo transport

A steady stream of material transport based on carriers and channels in living systems plays an extremely important role in normal life activities. Inspired by nature, researchers have extensively applied supramolecular cages in cargo transport because of their unique three-dimensional structures and excellent physicochemical properties. In this review, we will focus on the development of supramolecular cages as carriers and channels for cargo transport in abiotic and biological systems over the past fifteen years. In addition, we will discuss future challenges and potential applications of supramolecular cages in substance transport.

Label-free detection of biomolecules using inductively coupled plasma mass spectrometry (ICP-MS)

Bioassays using inductively coupled plasma mass spectrometry (ICP-MS) have gained increasing attention because of the high sensitivity of ICP-MS and the various strategies of labeling biomolecules with detectable metal tags. The classic strategy to tag the target biomolecules is through direct antibody-antigen interaction and DNA hybridization, and requires the separation of the bound from the unbound tags. Label-free ICP-MS techniques for biomolecular assays do not require direct labeling: they generate detectable metal ions indirectly from specific biomolecular reactions, such as enzymatic cleavage. Here, we highlight the development of three main strategies of label-free ICP-MS assays for biomolecules: (1) enzymatic cleavage of metal-labeled substrates, (2) release of immobilized metal ions from the DNA backbone, and (3) nucleic acid amplification-assisted aggregation and release of metal tags to achieve amplified detection. We briefly describe the fundamental basis of these label-free ICP-MS assays and discuss the benefits and drawbacks of various designs. Future research is needed to reduce non-specific adsorption and minimize background and interference. Analytical innovations are also required to confront challenges faced by in vivo applications.

Tuning Supramolecular Chirality in Iodinated Amphiphilic Peptides Through Tripeptide Linker Editing

Protease-cleavable supramolecular oligopeptide nanofilaments are promising materials for targeted therapeutics and diagnostics. In these systems, single amino acid substitutions can have profound effects on the supramolecular structure and consequent proteolytic degradation, which are critical parameters for their intended applications. Herein, we describe changes to the self-assembly and proteolytic cleavage of iodine containing sequences for future translation into matrix metalloprotease (MMP-9)-activated supramolecular radio-imaging probes. We use a systematic single amino acid exchange in the tripeptide linker region of these peptide amphiphiles to provide insights into the role of each residue in the supramolecular assemblies. These modifications resulted in dramatic changes in the nature of the assembled structures formed, including an unexpected chiral inversion. By using circular dichroism, atomic force microscopy, Fourier transform infrared spectroscopy, and molecular dynamics simulations, we found that the GD loop, a common motif in β-turn elements, induced a reversal of the chiral orientation of the assembled nanofibers. In addition to the impact on peptide packing and chirality, MMP-9-catalyzed hydrolysis was evaluated for the four peptides, with the β-sheet content found to be a stronger determinant of enzymatic hydrolysis than supramolecular chirality. These observations provide fundamental insights into the sequence design in protease cleavable amphiphilic peptides with the potential for radio-labeling and selective biomedical applications.

Recent Progress in Peptide-Based Molecular Probes for Disease Bioimaging

Recent strides in molecular pathology have unveiled distinctive alterations at the molecular level throughout the onset and progression of diseases. Enhancing the in vivo visualization of these biomarkers is crucial for advancing disease classification, staging, and treatment strategies. Peptide-based molecular probes (PMPs) have emerged as versatile tools due to their exceptional ability to discern these molecular changes with unparalleled specificity and precision. In this Perspective, we first summarize the methodologies for crafting innovative functional peptides, emphasizing recent advancements in both peptide library technologies and computer-assisted peptide design approaches. Furthermore, we offer an overview of the latest advances in PMPs within the realm of biological imaging, showcasing their varied applications in diagnostic and therapeutic modalities. We also briefly address current challenges and potential future directions in this dynamic field.

Multistage Self-Assembled Nanomaterials for Cancer Immunotherapy

Advances in nanotechnology have brought innovations to cancer therapy. Nanoparticle-based anticancer drugs have achieved great success from bench to bedside. However, insufficient therapy efficacy due to various physiological barriers in the body remains a key challenge. To overcome these biological barriers and improve the therapeutic efficacy of cancers, multistage self-assembled nanomaterials with advantages of stimuli-responsiveness, programmable delivery, and immune modulations provide great opportunities. In this review, we describe the typical biological barriers for nanomedicines, discuss the recent achievements of multistage self-assembled nanomaterials for stimuli-responsive drug delivery, highlighting the programmable delivery nanomaterials, in situ transformable self-assembled nanomaterials, and immune-reprogramming nanomaterials. Ultimately, we perspective the future opportunities and challenges of multistage self-assembled nanomaterials for cancer immunotherapy.

Advancements in Intraoperative Near-Infrared Fluorescence Imaging for Accurate Tumor Resection: A Promising Technique for Improved Surgical Outcomes and Patient Survival

Clear surgical margins for solid tumor resection are essential for preventing cancer recurrence and improving overall patient survival. Complete resection of tumors is often limited by a surgeon's ability to accurately locate malignant tissues and differentiate them from healthy tissue. Therefore, techniques or imaging modalities are required that would ease the identification and resection of tumors by real-time intraoperative visualization of tumors. Although conventional imaging techniques such as positron emission tomography (PET), computed tomography (CT), magnetic resonance imaging (MRI), or radiography play an essential role in preoperative diagnostics, these cannot be utilized in intraoperative tumor detection due to their large size, high cost, long imaging time, and lack of cancer specificity. The inception of several imaging techniques has paved the way to intraoperative tumor margin detection with a high degree of sensitivity and specificity. Particularly, molecular imaging using near-infrared fluorescence (NIRF) based nanoprobes provides superior imaging quality due to high signal-to-noise ratio, deep penetration to tissues, and low autofluorescence, enabling accurate tumor resection and improved survival rates. In this review, we discuss the recent developments in imaging technologies, specifically focusing on NIRF nanoprobes that aid in highly specific intraoperative surgeries with real-time recognition of tumor margins.

MMP-responsive nanomaterials

Matrix metalloproteinases (MMP) are enzymes that degrade the extracellular matrix and regulate essential normal cell behaviors. Inhibition of these enzymes has been a strategy for anti-cancer therapy since the 1990s, but with limited success. A new type of MMP-targeting strategy exploits the innate selective hydrolytic activity and consequent catalytic signal amplification of the proteinases, rather than inhibiting it. Using nanomaterials, the enzymatic chemical reaction can trigger the temporal and spatial activation of the anti-cancer effects, amplify the associated response, and cause mechanical damage or report on cancer cells. We analyzed nearly 60 literature studies that incorporate chemical design strategies that lead to spatial, temporal, and mechanical control of the anti-cancer effect through four modes of action: nanomaterial shrinkage, induced aggregation, formation of cytotoxic nanofibers, and activation by de-PEGylation. From the literature analysis, we derived chemical design guidelines to control and enhance MMP activation of nanomaterials of various chemical compositions (peptide, lipid, polymer, inorganic). Finally, the review includes a guide on how multiple characteristics of the nanomaterial, such as substrate modification, supramolecular structure, and electrostatic charge should be collectively considered for the targeted MMP to result in optimal kinetics of enzyme action on the nanomaterial, which allow access to amplification and additional levels of spatial, temporal, and mechanical control of the response. Although this review focuses on the design strategies of MMP-responsive nanomaterials in cancer applications, these guidelines are expected to be generalizable to systems that target MMP for treatment or detection of cancer and other diseases, as well as other enzyme-responsive nanomaterials.

Matrix Metalloproteinase-Responsive Drug Delivery Systems

Matrix metalloproteinases (MMPs) are a class of endopeptidases that are dependent on zinc and facilitate the degradation of extracellular matrix (ECM) proteins, thereby playing pivotal parts in human physiology and pathology. MMPs regulate normal tissue and cellular functions, including tissue development, remodeling, angiogenesis, bone formation, and wound healing. Several diseases, including cancer, inflammation, cardiovascular diseases, and nervous system disorders, have been linked to dysregulated expression of specific MMP subtypes, which can promote tumor progression, metastasis, and inflammation. Various MMP-responsive drug delivery and release systems have been developed by harnessing cleavage activities and overexpression of MMPs in affected regions. Herein, we review the structure, substrates, and physiological and pathological functions of various MMPs and highlight the strategies for designing MMP-responsive nanoparticles to improve the targeting efficiency, penetration, and protection of therapeutic payloads.

Effect of the Lipid Landscape on the Efficacy of Cell-Penetrating Peptides

Every cell biological textbook teaches us that the main role of the plasma membrane is to separate cells from their neighborhood to allow for a controlled composition of the intracellular space. The mostly hydrophobic nature of the cell membrane presents an impenetrable barrier for most hydrophilic molecules larger than 1 kDa. On the other hand, cell-penetrating peptides (CPPs) are capable of traversing this barrier without compromising membrane integrity, and they can do so on their own or coupled to cargos. Coupling biologically and medically relevant cargos to CPPs holds great promise of delivering membrane-impermeable drugs into cells. If the cargo is able to interact with certain cell types, uptake of the CPP-drug complex can be tailored to be cell-type-specific. Besides outlining the major membrane penetration pathways of CPPs, this review is aimed at deciphering how properties of the membrane influence the uptake mechanisms of CPPs. By summarizing an extensive body of experimental evidence, we argue that a more ordered, less flexible membrane structure, often present in the very diseases planned to be treated with CPPs, decreases their cellular uptake. These correlations are not only relevant for understanding the cellular biology of CPPs, but also for rationally improving their value in translational or clinical applications.

Activatable fluorescent probes for real-time imaging-guided tumor therapy

Surgery and drug therapy are the two principal options for cancer treatment. However, their clinical benefits are hindered by the difficulty of accurate location of the tumors and timely monitoring of the treatment efficacy of drugs, respectively. Rapid development of imaging techniques provides promising tools to address these challenges. Compared with conventional imaging techniques such as magnetic resonance imaging and computed tomography etc., fluorescence imaging exhibits high spatial resolution, real-time imaging capability, and relatively low costs devices. The advancements in fluorescent probes further accelerate the implementation of fluorescence imaging in tumor diagnosis and treatment monitoring. In particular, the emergence of site-specifically activatable fluorescent probes fits the demands of tumor delineation and real-time feedback of the treatment efficacy. A variety of small molecule probes or nanoparticle-based probes have been developed and explored for the above-mentioned applications. This review will discuss recent advances in fluorescent probes with a special focus on activatable nanoprobes and highlight the potential implementation of activatable nanoprobes in fluorescence imaging-guided surgery as well as imaging-guided drug therapy.

Peptide-based diagnostic and therapeutic agents: Where we are and where we are heading?

Peptides are increasingly present in all branches of medicine as innovative drugs, imaging agents, theragnostic, and constituent moieties of other sophisticated drugs such as peptide-drug conjugates. Due to new developments in chemical synthesis strategies, computational biology, recombinant technology, and chemical biology, peptide drug development has made a great progress in the last decade. Numerous natural peptides and peptide mimics have been obtained and studied, covering multiple therapeutic areas. Even though peptides have been investigated across the wide therapeutic spectrum, oncology, metabolism, and endocrinology are the most frequent medical indications of them. This review summarizes the current use of and the emerging new opportunities of peptides for diagnosis and treatment of various diseases.

Nanoparticles in the diagnosis and treatment of cancer metastases: Current and future perspectives

Metastasis accounts for greater than 90% of cancer-related deaths. Despite recent advancements in conventional chemotherapy, immunotherapy, targeted therapy, and their rational combinations, metastatic cancers remain essentially untreatable. The distinct obstacles to treat metastases include their small size, high multiplicity, redundancy, therapeutic resistance, and dissemination to multiple organs. Recent advancements in nanotechnology provide the numerous applications in the diagnosis and prophylaxis of metastatic diseases, including the small particle size to penetrate cell membrane and blood vessels and their capacity to transport complex molecular 'cargo' particles to various metastatic regions such as bones, brain, liver, lungs, and lymph nodes. Indeed, nanoparticles (NPs) have demonstrated a significant ability to target specific cells within these organs. In this regard, the purpose of this review is to summarize the present state of nanotechnology in terms of its application in the diagnosis and treatment of metastatic cancer. We intensively reviewed applications of NPs in fluorescent imaging, PET scanning, MRI, and photoacoustic imaging to detect metastasis in various cancer models. The use of targeted NPs for cancer ablation in conjunction with chemotherapy, photothermal treatment, immuno therapy, and combination therapy is thoroughly discussed. The current review also highlights the research opportunities and challenges of leveraging engineering technologies with cancer cell biology and pharmacology to fabricate nanoscience-based tools for treating metastases.

Protease-Responsive Potential-Tunable AIEgens for Cell Selective Imaging of TMPRSS2 and Accurate Inhibitor Screening

Transmembrane protease serine 2 (TMPRSS2) is a plasma membrane protease that activates both spike protein of coronaviruses for cell entry and oncogenic signaling pathways for tumor progression. TMPRSS2 inhibition can reduce cancer invasion and metastasis and partially prevent the entry of SARS-CoV-2 into host cells. Thus, there is an urgent need for both TMPRSS2-selective imaging and precise screening of TMPRSS2 inhibitors. Here, we report a TMPRSS2-responsive surface-potential-tunable peptide-conjugated probe (EGTP) with aggregation-induced emission (AIE) features for TMPRSS2 selective imaging and accurate inhibitor screening. The amphiphilic EGTP was constructed with tunable surface potential and responsive efficiency with TMPRSS2 and its inhibitor. The rational construction of AIE luminogens (AIEgens) with modular peptides indicated that the cleavage of EGTP led to a gradual aggregation with bright fluorescence in high TMPRSS2-expressing cells. This strategy may have value for selective detection of cancer cells, SARS-CoV-2-target cells, and screening of protease inhibitors.

Combination of chemotherapy and immune checkpoint therapy by the immunoconjugates-based nanocomplexes synergistically improves therapeutic efficacy in SCLC

Although the etoposide and carboplatin (EP) combination strategy has been the first-line chemotherapy, patients with extensive-stage disease small-cell lung cancer (SCLC) still have poor survival outcomes. Our retrospective analysis revealed that 46 patients with SCLC only achieved medium overall survival (OS) of 11.6 months after treated by EP. Recently, it was demonstrated that combination therapy of PD1/PD-L1 immune checkpoint blocker and EP could significantly improve the OS of SCLC patients. However, the serious treatment-related toxicity leaded to a high rate of treatment-discontinuation or even death. In the present study, we have developed a novel TPP1-conjugated nanocomplex, abbreviated as TPP1NP-EP, which was co-loaded with carboplatin (CBP) and etoposide (VP16). The TPP1 was a PD-L1 targeting peptide and conjugated on the surface of nanocomplex by a matrix metalloproteinase (MMP-2/9)-cleavable peptide linker sequence PLGLAG. For dual-loading of CBP and VP16, the CBP was chemically conjugated with poly(ethylene glycol) (PEG)-poly(caprolactone) (PCL) by pH-sensitive hydrazone bond and the VP16 was physically encapsulated by emulsion-solvent evaporation method. In vitro and in vivo experiments demonstrated an excellent anti-tumor effect of TPP1NP-EP on SCLC and improved safety. In conclusion, the present study has provided a promising strategy for treatment of malignant SCLC.

Cell-Penetrating Peptides (CPPs) as Therapeutic and Diagnostic Agents for Cancer

Cell-Penetrating Peptides (CPPs) are short peptides consisting of <30 amino acids. Their ability to translocate through the cell membrane while carrying large cargo biomolecules has been the topic of pre-clinical and clinical trials. The ability to deliver cargo complexes through membranes yields potential for therapeutics and diagnostics for diseases such as cancer. Upon cellular entry, some CPPs have the ability to target specific organelles. CPP-based intracellular targeting strategies hold tremendous potential as they can improve efficacy and reduce toxicities and side effects. Further, recent clinical trials show a significant potential for future CPP-based cancer treatment. In this review, we summarize recent advances in CPPs based on systematic searches in PubMed, Embase, Web of Science, and Scopus databases until 30 September 2022. We highlight targeted delivery and explore the potential uses for CPPs as diagnostics, drug delivery, and intrinsic anti-cancer agents.

Tuning of Peptide Cytotoxicity with Cell Penetrating Motif Activatable by Matrix Metalloproteinase-2

Although diverse cell penetrating motifs not only from naturally occurring proteins but also from synthetic peptides have been discovered and developed, the selectivity of cargo delivery connected to these motifs into the desired target cells is generally low. Here, we demonstrate the selective cytotoxicity tuning of an anticancer KLA peptide with a cell penetrating motif activatable by matrix metalloproteinase-2 (MMP2). The anionic masking sequence introduced at the end of the KLA peptide through an MMP2-cleavable linker is selectively cleaved by MMP2 and the cationic cell penetrating motif is activated. Upon treatment of the peptide to H1299 cells (high MMP2 level), it is selectively internalized into the cells by MMP2, which consequently induces membrane disruption and cell death. In contrast, the peptide shows negligible cytotoxicity toward A549 cancer cells with low MMP2 levels. Furthermore, the selective therapeutic efficacy of the peptide induced by MMP2 is also corroborated using in vivo study.

Tumor-Associated Enzyme-Activatable Spherical Nucleic Acids

Maximizing the tissue-targeting efficiency of nanomaterials while also protecting them from rapid clearance from the bloodstream and limiting their immunogenicity remains a central problem in the field of systemic-administered nanomedicine. Herein, we introduce a generalizable strategy to simultaneously increase tumor accumulation, prolong blood circulation, and limit nonspecific immune activation of nanomaterials via peptide-based, tumor-responsive, "sheddable" coatings. Spherical nucleic acids (SNAs) were designed and synthesized to contain an exterior coating composed of zwitterionic polypeptides with recognition sequences for tumor-associated proteases. In the presence of matrix metalloproteinases (MMPs), the polypetide coating is rapidly cleaved, leading to increased cellular uptake of these SNAs, relative to SNAs containing nonsheddable shells. Moreover, the zwitterionic nature of the polypeptide shell shields the SNAs from immune system recognition, which extends their blood circulation time and improves tumor accumulation and in vivo cellular uptake relative to control SNAs with no protective coating. Taken together, these results indicate that this strategy is a viable method for increasing nanoparticle tumor accumulation and can have utility for the systemic delivery of oligonucleotides and nanomaterials to target cells in vivo with low immunogenicity.

Progress on Multifunction Enzyme-Activated Organic Fluorescent Probes for Bioimaging

Bioimaging techniques are of increasing importance in clinical and related fields, which also have been successfully applied in the in vivo/in vitro imaging system. Due to the vital factor of enzymes in biological systems, enzyme-activated fluorophores, which could turn “on” the fluorescence signal from an “off” state, offer non-invasive and effective potential for the accurate bioimaging of particular cells, tissues, or bacteria. Comparing with the traditional imaging probes, enzyme-activated organic small fluorophores can visualize living cells within small animals with high sensitivity, high imaging resolution, non-invasiveness, and real-time feedback. In this mini review, well-designed enzyme-activated organic fluorescent probes with multiple functions are exclusively reviewed through the latest development and progress, focusing on probe design strategy, fluorescence property, enzyme activation process, and bioimaging applications. It is worth noting that multi-enzyme-activated strategies, which could avoid the production of “false-positive” signals in complex biological systems, effectively provide high selective and real-time bioimaging, indicating the exciting potential of intraoperative fluorescence imaging and diagnosis tools.

Nanotechnology and Matrix Metalloproteinases in Cancer Diagnosis and Treatment

Cancer is still one of the leading causes of death worldwide. This great mortality is due to its late diagnosis when the disease is already at advanced stages. Although the efforts made to develop more effective treatments, around 90% of cancer deaths are due to metastasis that confers a systemic character to the disease. Likewise, matrix metalloproteinases (MMPs) are endopeptidases that participate in all the events of the metastatic process. MMPs’ augmented concentrations and an increased enzymatic activity have been considered bad prognosis markers of the disease. Therefore, synthetic inhibitors have been created to block MMPs’ enzymatic activity. However, they have been ineffective in addition to causing considerable side effects. On the other hand, nanotechnology offers the opportunity to formulate therapeutic agents that can act directly on a target cell, avoiding side effects and improving the diagnosis, follow-up, and treatment of cancer. The goal of the present review is to discuss novel nanotechnological strategies in which MMPs are used with theranostic purposes and as therapeutic targets to control cancer progression.

Fibroblast growth factor homologous factors serve as a molecular rheostat in tuning arrhythmogenic cardiac late sodium current

Voltage-gated sodium (Nav1.5) channels support the genesis and brisk spatial propagation of action potentials in the heart. Disruption of NaV1.5 inactivation results in a small persistent Na influx known as late Na current (I Na,L), which has emerged as a common pathogenic mechanism in both congenital and acquired cardiac arrhythmogenic syndromes. Here, using low-noise multi-channel recordings in heterologous systems, LQTS3 patient-derived iPSCs cardiomyocytes, and mouse ventricular myocytes, we demonstrate that the intracellular fibroblast growth factor homologous factors (FHF1-4) tune pathogenic I Na,L in an isoform-specific manner. This scheme suggests a complex orchestration of I Na,L in cardiomyocytes that may contribute to variable disease expressivity of NaV1.5 channelopathies. We further leverage these observations to engineer a peptide-inhibitor of I Na,L with a higher efficacy as compared to a well-established small-molecule inhibitor. Overall, these findings lend insights into molecular mechanisms underlying FHF regulation of I Na,L in pathophysiology and outline potential therapeutic avenues.

Design, Synthesis, and Bioevaluation of Novel Enzyme-Triggerable Cell Penetrating Peptide-Based Dendrimers for Targeted Delivery of Camptothecin and Cancer Therapy

Novel enzyme-triggerable cell penetrating peptide (ETCPP) dendrimers with a camptothecin (CPT) warhead were designed and synthesized based on an amphiphilic penetrating peptide (FKKFFRKLL, discovered by us before). Among the newly synthesized ETCPP dendrimer conjugates, BL_Oc-SS-CPT (a high-generation dendrimer) exhibited the highest activity with IC₅₀s in the nanomolar range (31-747 nM) against a panel of cancer cells, which is 3-10 times better than that of CPT. BL_Oc-SS-CPT remained intact during transit to target cells and in normal tissues with a plasma half-life of 4.2 h, 2.3-fold longer than that of the monomer (1.8 h). Once reaching the tumor site, BL_Oc-SS-CPT gradually released CPT in the presence of excessive matrix metalloproteinase-2/9 and GSH in cancer cells. Importantly, BL_Oc-SS-CPT exhibited excellent in vivo tumor targeting capability and antitumor efficacy with benign toxicity profiles. Thus, the novel ETCPP dendrimer-based drug delivery system (e.g., BL_Oc-SS-CPT) represents a safe and effective strategy for targeted cancer therapy.

Advanced Optical Imaging-Guided Nanotheranostics towards Personalized Cancer Drug Delivery

Nanomedicine involves the use of nanotechnology for clinical applications and holds promise to improve treatments. Recent developments offer new hope for cancer detection, prevention and treatment; however, being a heterogenous disorder, cancer calls for a more targeted treatment approach. Personalized Medicine (PM) aims to revolutionize cancer therapy by matching the most effective treatment to individual patients. Nanotheranostics comprise a combination of therapy and diagnostic imaging incorporated in a nanosystem and are developed to fulfill the promise of PM by helping in the selection of treatments, the objective monitoring of response and the planning of follow-up therapy. Although well-established imaging techniques, such as Magnetic Resonance Imaging (MRI), Computed Tomography (CT), Positron Emission Tomography (PET) and Single-Photon Emission Computed Tomography (SPECT), are primarily used in the development of theranostics, Optical Imaging (OI) offers some advantages, such as high sensitivity, spatial and temporal resolution and less invasiveness. Additionally, it allows for multiplexing, using multi-color imaging and DNA barcoding, which further aids in the development of personalized treatments. Recent advances have also given rise to techniques permitting better penetration, opening new doors for OI-guided nanotheranostics. In this review, we describe in detail these recent advances that may be used to design and develop efficient and specific nanotheranostics for personalized cancer drug delivery.

Stimuli Induced Uptake of Protein-Like Peptide Brush Polymers

Recently, we presented a strategy for packaging peptides as side-chains in high-density brush polymers. For this globular protein-like polymer (PLP) formulation, therapeutic peptides were shown to resist proteolytic degradation, enter cells efficiently and maintain biological function. In this paper, we establish the role charge plays in dictating the cellular uptake of these peptide formulations, finding that peptides with a net positive charge will enter cells when polymerized, while those formed from anionic or neutral peptides remain outside of cells. Given these findings, we explored whether cellular uptake could be selectively induced by a stimulus. In our design, a cationic peptide is appended to a sequence of charge-neutralizing anionic amino acids through stimuli-responsive cleavable linkers. As a proof-of-concept study, we tested this strategy with two different classes of stimuli, exogenous UV light and an enzyme (a matrix metalloproteinase) associated with the inflammatory response. The key finding is that these materials enter cells only when acted upon by the stimulus. This approach makes it possible to achieve delivery of the polymers, therapeutic peptides or an appended cargo into cells in response to an appropriate stimulus.

The Impact of Tyrosine Iodination on the Aggregation and Cleavage Kinetics of MMP-9-Responsive Peptide Sequences

Matrix metalloproteinase (MMP) enzymes are over-expressed by some metastatic cancers, in which they are responsible for the degradation and remodeling of the extracellular matrix. In recent years, MMPs have emerged as promising targets for enzyme-responsive diagnostic probes because oligopeptides can be designed to be selectively hydrolyzed by exposure to these enzymes. With the ultimate goal of developing radio-iodinated peptides as supramolecular building blocks for MMP-sensitive tools for nuclear imaging and therapy, we designed three MMP-9-responsive peptides containing either tyrosine or iodotyrosine to assess the impact of iodotyrosine introduction to the peptide structure and cleavage kinetics. We found that the peptides containing iodotyrosine underwent more rapid and more complete hydrolysis by MMP-9. While the peptides under investigation were predominantly disordered, it was found that iodination increased the degree of aromatic residue-driven aggregation of the peptides. We determined that these iodination-related trends stem from the improved overall intramolecular order through H- and halogen bonding, in addition to intermolecular organization of the self-assembled peptides due to steric and electrostatic effects introduced by the halogenated tyrosine. These fundamental observations provide insights for the development of enzyme-triggered peptide aggregation tools for localized radioactive iodine-based tumor imaging.

Development of nanotechnology-mediated precision radiotherapy for anti-metastasis and radioprotection

Radiotherapy (RT), including external beam RT and internal radiation therapy, uses high-energy ionizing radiation to kill tumor cells.

Dimensionless parameter predicts bacterial prodrug success

Understanding mechanisms of antibiotic failure is foundational to combating the growing threat of multidrug-resistant bacteria. Prodrugs-which are converted into a pharmacologically active compound after administration-represent a growing class of therapeutics for treating bacterial infections but are understudied in the context of antibiotic failure. We hypothesize that strategies that rely on pathogen-specific pathways for prodrug conversion are susceptible to competing rates of prodrug activation and bacterial replication, which could lead to treatment escape and failure. Here, we construct a mathematical model of prodrug kinetics to predict rate-dependent conditions under which bacteria escape prodrug treatment. From this model, we derive a dimensionless parameter we call the Bacterial Advantage Heuristic (BAH) that predicts the transition between prodrug escape and successful treatment across a range of time scales (1-104  h), bacterial carrying capacities (5 × 104 -105  CFU/µl), and Michaelis constants (KM  = 0.747-7.47 mM). To verify these predictions in vitro, we use two models of bacteria-prodrug competition: (i) an antimicrobial peptide hairpin that is enzymatically activated by bacterial surface proteases and (ii) a thiomaltose-conjugated trimethoprim that is internalized by bacterial maltodextrin transporters and hydrolyzed by free thiols. We observe that prodrug failure occurs at BAH values above the same critical threshold predicted by the model. Furthermore, we demonstrate two examples of how failing prodrugs can be rescued by decreasing the BAH below the critical threshold via (i) substrate design and (ii) nutrient control. We envision such dimensionless parameters serving as supportive pharmacokinetic quantities that guide the design and administration of prodrug therapeutics.

Activatable molecular probes for fluorescence-guided surgery, endoscopy and tissue biopsy

The real-time, dynamic optical visualization of lesions and margins ensures not only complete resection of the malignant tissues but also better preservation of the vital organs/tissues during surgical procedures. Most imaging probes with an "always-on" signal encounter high background noise due to their non-specific accumulation in normal tissues. By contrast, activatable molecular probes only "turn on" their signals upon reaction with the targeted biomolecules that are overexpressed in malignant cells, offering high target-to-background ratios with high specificity and sensitivity. This review summarizes the recent progress of activatable molecular probes in surgical imaging and diagnosis. The design principle and mechanism of activatable molecular probes are discussed, followed by specific emphasis on applications ranging from fluorescence-guided surgery to endoscopy and tissue biopsy. Finally, potential challenges and perspectives in the field of activatable molecular probe-enabled surgical imaging are discussed.

Fluorescence-Based On-Resin Detection of Three Model Proteases

A new approach to on-resin detection of three model proteases (trypsin, chymotrypsin, and thrombin) has been developed, while at the same time already described methodology for simultaneous detection of two enzymes (trypsin and chymotrypsin) has been additionally generalized. Appropriate immobilized substrates, comprising specifically cleavable peptide sequences capped with fluorescent dyes, have been synthesized on Rink Amide PEGA resin or Amino PEGA resin modified with backbone amide linker (BAL). Resulting solid support-bound probes were then dispersed into Tris-HCl buffer solution (pH = 8.0) and subjected to enzymatic cleavage. Liberated fluorophores have been tracked by fluorescence measuring. The competitive activities of studied proteases towards the thrombin probe have been efficiently limited and controlled by employing a Bowman-Birk inhibitor into a system.

Emerging Nano-Based Strategies Against Drug Resistance in Tumor Chemotherapy

Drug resistance is the most significant causes of cancer chemotherapy failure. Various mechanisms of drug resistance include tumor heterogeneity, tumor microenvironment, changes at cellular levels, genetic factors, and other mechanisms. In recent years, more attention has been paid to tumor resistance mechanisms and countermeasures. Nanomedicine is an emerging treatment platform, focusing on alternative drug delivery and improved therapeutic effectiveness while reducing side effects on normal tissues. Here, we reviewed the principal forms of drug resistance and the new possibilities that nanomaterials offer for overcoming these therapeutic barriers. Novel nanomaterials based on tumor types are an excellent modality to equalize drug resistance that enables gain more rational and flexible drug selectivity for individual patient treatment. With the emergence of advanced designs and alternative drug delivery strategies with different nanomaterials, overcome of multidrug resistance shows promising and opens new horizons for cancer therapy. This review discussed different mechanisms of drug resistance and recent advances in nanotechnology-based therapeutic strategies to improve the sensitivity and effectiveness of chemotherapeutic drugs, aiming to show the advantages of nanomaterials in overcoming of drug resistance for tumor chemotherapy, which could accelerate the development of personalized medicine.

Enzymatically Transformable Polymersome-Based Nanotherapeutics to Eliminate Minimal Relapsable Cancer

Prevention of metastatic and local-regional recurrence of cancer after surgery remains difficult. Targeting postsurgical premetastatic niche and microresiduals presents an excellent prospective opportunity but is often challenged by poor therapeutic delivery into minimal residual tumors. Here, an enzymatically transformable polymer-based nanotherapeutic approach is presented that exploits matrix metalloproteinase (MMP) overactivation in tumor-associated tissues to guide the codelivery of colchicine (microtubule-disrupting and anti-inflammatory agent) and marimastat (MMP inhibitor). The dePEGylation of polymersomes catalyzed by MMPs not only exposes the guanidine moiety to improve tissue/cell-targeting/retention to increase bioavailability, but also differentially releases marimastat and colchicine to engage their extracellular (MMPs) and intracellular (microtubules) targets of action, respectively. In primary tumors/overt metastases, the vasculature-specific targeting of nanotherapeutics can function synchronously with the enhanced permeability and retention effect to deter malignant progression of metastatic breast cancer. After the surgical removal of large primary tumors, nanotherapeutic agents are localized in the premetastatic niche and at the site of the postsurgical wound, disrupting the premetastatic microenvironment and eliminating microresiduals, which radically reduces metastatic and local-regional recurrence. The findings suggest that nanotherapeutics can safely widen the therapeutic window to resuscitate colchicine and MMP inhibitors for other inflammatory disorders.

Recent Progress of Surface Modified Nanomaterials for Scavenging Reactive Oxygen Species in Organism

Reactive oxygen species (ROS) are essential for normal physiological processes and play important roles in signal transduction, immunity, and tissue homeostasis. However, excess ROS may have a negative effect on the normal cells leading to various diseases. Nanomaterials are an attractive therapeutic alternative of antioxidants and possess an intrinsic ability to scavenge ROS. Surface modification for nanomaterials is a critical strategy to improve their comprehensive performances. Herein, we review the different surface modified strategies for nanomaterials to scavenge ROS and their inherent antioxidant capability, mechanisms of action, and biological applications. At last, the primary challenges and future perspectives in this emerging research frontier have also been highlighted. It is believed that this review paper will offer a top understanding and guidance on engineering future high-performance surface modified ROS scavenging nanomaterials for wide biomedical applications.

Anti-Inflammatory Nanotherapeutics by Targeting Matrix Metalloproteinases for Immunotherapy of Spinal Cord Injury

Neuroinflammation is critically involved in the repair of spinal cord injury (SCI), and macrophages associated with inflammation propel the degeneration or recovery in the pathological process. Currently, efforts have been focused on obtaining efficient therapeutic anti-inflammatory drugs to treat SCI. However, these drugs are still unable to penetrate the blood spinal cord barrier and lack the ability to target lesion areas, resulting in unsatisfactory clinical efficacy. Herein, a polymer-based nanodrug delivery system is constructed to enhance the targeting ability. Because of increased expression of matrix metalloproteinases (MMPs) in injured site after SCI, MMP-responsive molecule, activated cell-penetrating peptides (ACPP), is introduced into the biocompatible polymer PLGA-PEI-mPEG (PPP) to endow the nanoparticles with the ability for diseased tissue-targeting. Meanwhile, etanercept (ET), a clinical anti-inflammation treatment medicine, is loaded on the polymer to regulate the polarization of macrophages, and promote locomotor recovery. The results show that PPP-ACPP nanoparticles possess satisfactory lesion targeting effects. Through inhibited consequential production of proinflammation cytokines and promoted anti-inflammation cytokines, ET@PPP-ACPP could decrease the percentage of M1 macrophages and increase M2 macrophages. As expected, ET@PPP-ACPP accumulates in lesion area and achieves effective treatment of SCI; this confirmed the potential of nano-drug loading systems in SCI immunotherapy.

Tumor-targeted Drug Delivery by Nanocomposites

BACKGROUND

Tumor-targeted delivery by nanoparticles is a great achievement towards the use of highly effective drug at very low doses. The conventional development of tumor-targeted delivery by nanoparticles is based on enhanced permeability and retention (EPR) effect and endocytosis based on receptor-mediated are very demanding due to the biological and natural complications of tumors as well as the restrictions on the design of the accurate nanoparticle delivery systems.

METHODS

Different tumor environment stimuli are responsible for triggered multistage drug delivery systems (MSDDS) for tumor therapy and imaging. Physicochemical properties, such as size, hydrophobicity and potential transform by MSDDS because of the physiological blood circulation different, intracellular tumor environment. This system accomplishes tumor penetration, cellular uptake improved, discharge of drugs on accurate time, and endosomal discharge.

RESULTS

Maximum drug delivery by MSDDS mechanism to target therapeutic cells and also tumor tissues and sub cellular organism. Poorly soluble compounds and bioavailability issues have been faced by pharmaceutical industries, which are resolved by nanoparticle formulation.

CONCLUSION

In our review, we illustrate different types of triggered moods and stimuli of the tumor environment, which help in smart multistage drug delivery systems by nanoparticles, basically a multi-stimuli sensitive delivery system, and elaborate their function, effects, and diagnosis.

Cell-Penetrating Peptides: Applications in Tumor Diagnosis and Therapeutics

Since their identification over twenty-five years ago, the plethora of cell-penetrating peptides (CPP) and their applications has skyrocketed. These 5 to 30 amino acid in length peptides have the unique property of breaching the cell membrane barrier while carrying cargoes larger than themselves into cells in an intact, functional form. CPPs can be conjugated to fluorophores, activatable probes, radioisotopes or contrast agents for imaging tissues, such as tumors. There is no singular mechanism for translocation of CPPs into a cell, and therefore, many CPPs are taken up by a multitude of cell types, creating the challenge of tumor-specific translocation and hindering clinical effectiveness. Varying strategies have been developed to combat this issue and enhance their diagnostic potential by derivatizing CPPs for better targeting by constructing specific cell-activated forms. These methods are currently being used to image integrin-expressing tumors, breast cancer cells, human histiocytic lymphoma and protease-secreting fibrosarcoma cells, to name a few. Additionally, identifying safe, effective therapeutics for malignant tumors has long been an active area of research. CPPs can circumvent many of the complications found in treating cancer with conventional therapeutics by targeted delivery of drugs into tumors, thereby decreasing off-target side effects, a feat not achievable by currently employed conventional chemotherapeutics. Myriad types of chemotherapeutics such as tyrosine kinase inhibitors, antitumor antibodies and nanoparticles can be functionally attached to these peptides, leading to the possibility of delivering established and novel cancer therapeutics directly to tumor tissue. While much research is needed to overcome potential issues with these peptides, they offer a significant advancement over current mechanisms to treat cancer. In this review, we present a brief overview of the research, leading to identification of CPPs with a comprehensive state-of-the-art review on the role of these novel peptides in both cancer diagnostics as well as therapeutics.

Quantifying and visualising the nuances of cellular dynamics in vivo using intravital imaging

Intravital imaging is a powerful technology used to quantify and track dynamic changes in live cells and tissues within an intact environment. The ability to watch cell biology in real-time 'as it happens' has provided novel insight into tissue homeostasis, as well as disease initiation, progression and response to treatment. In this minireview, we highlight recent advances in the field of intravital microscopy, touching upon advances in awake versus anaesthesia-based approaches, as well as the integration of biosensors into intravital imaging. We also discuss current challenges that, in our opinion, need to be overcome to further advance the field of intravital imaging at the single-cell, subcellular and molecular resolution to reveal nuances of cell behaviour that can be targeted in complex disease settings.

A size-shrinkable matrix metallopeptidase-2-sensitive delivery nanosystem improves the penetration of human programmed death-ligand 1 siRNA into lung-tumor spheroids

Given the maturation of small-interfering RNA (siRNA) techniques with nanotechnology, and because overexpression of human programmed death-ligand 1 (PD-L1) is crucial for T cell inactivation and immunosuppression of the tumor microenvironment, application of siRNA-PD-L1 has demonstrated positive progress in preclinical studies; however, the limited penetration of this compound into solid tumors remains a challenge. To decrease PD-L1 expression and increase the penetration efficacy of solid tumors, we synthesized a novel tumor-microenvironment-sensitive delivery polymer by conjugating hyaluronic acid (HA) to polyethyleneimine (PEI), with a matrix metalloproteinase-2 (MMP-2)-sensitive peptide acting as the linker (HA-P-PEI), for use in delivery of PD-L1-siRNA. Concurrent synthesis of a linker-less HA-PEI compound allowed confirmation that negatively charged siRNA can be complexed onto the positively charged HA-PEI and HA-P-PEI compounds to form nanoparticles with the same particle size and uniform distribution with serum stability. We found that the size of the HA-P-PEI/siRNA nanoparticles decreased to <10 nm upon addition of MMP-2, and that H1975 cells overexpressing CD44, PD-L1, and MMP-2 aided confirmation of the delivery efficacy of the HA-P-PEI/siRNA nanocomplexes. Additionally, the use of HA-P-PEI caused less cytotoxicity than PEI alone, demonstrating its high cellular uptake. Moreover, pretreatment with MMP-2 increased nanocomplex tumor permeability, and western blot showed that HA-P-PEI/PD-L1-siRNA efficiently downregulated the PD-L1 expression in H1975 cells. These results demonstrated a novel approach for siRNA delivery and tumor penetration for future clinical applications in cancer treatment.

Cell-penetrating peptides (CPPs): an overview of applications for improving the potential of nanotherapeutics

In the field of nanotherapeutics, gaining cellular entry into the cytoplasm of the target cell continues to be an ultimate challenge. There are many physicochemical factors such as charge, size and molecular weight of the molecules and delivery vehicles, which restrict their cellular entry. Hence, to dodge such situations, a class of short peptides called cell-penetrating peptides (CPPs) was brought into use. CPPs can effectively interact with the cell membrane and can assist in achieving the desired intracellular entry. Such strategy is majorly employed in the field of cancer therapy and diagnosis, but now it is also used for other purposes such as evaluation of atherosclerotic plaques, determination of thrombin levels and HIV therapy. Thus, the current review expounds on each of these mentioned aspects. Further, the review briefly summarizes the basic know-how of CPPs, their utility as therapeutic molecules, their use in cancer therapy, tumor imaging and their assistance to nanocarriers in improving their membrane penetrability. The review also discusses the challenges faced with CPPs pertaining to their stability and also mentions the strategies to overcome them. Thus, in a nutshell, this review will assist in understanding how CPPs can present novel possibilities for resolving the conventional issues faced with the present-day nanotherapeutics.

In Vitro and In Vivo Cell Uptake of a Cell-Penetrating Peptide Conjugated with Fluorescent Dyes Having Different Chemical Properties

Simple Summary

In fluorescence imaging employing a targeting strategy, fluorescent dyes conjugated with ligands may alter the pharmacokinetics of the conjugates. The aim of this study was to investigate whether in vitro and in vivo cell uptake are affected when fluorescent dyes with different chemical properties are conjugated with a ligand. The results show that attention should be paid to the chemical properties of fluorescent dyes in designing fluorescent imaging agents.

Abstract

In molecular imaging, a targeting strategy with ligands is widely used because specificity can be significantly improved. In fluorescence imaging based on a targeting strategy, the fluorescent dyes conjugated with ligands may affect the targeting efficiency depending on the chemical properties. Herein, we used a cell-penetrating peptide (CPP) as a ligand with a variety of fluorescent cyanine dye. We investigated in vitro and in vivo cell uptake of the dye-CPP conjugates when cyanine dyes with differing charge and hydrophilicity/lipophilicity were used. The results showed that the conjugates with positively charged and lipophilic cyanine dyes accumulated in cancer cells in vitro, but there was almost no accumulation in tumors in vivo. On the other hand, the conjugates with negatively charged and hydrophilic cyanine dyes did not accumulate in cancer cells in vitro, but fluorescence was observed in tumors in vivo. These results show that there are some cases in which the cell uptake of the dye-peptide conjugates may differ significantly between in vitro and in vivo experiments due to the chemical properties of the fluorescent dyes. This suggests that attention should be paid to the chemical properties of fluorescent dyes in fluorescence imaging based on a targeting strategy.

Improvement of Gold Nanorods in Photothermal Therapy: Recent Progress and Perspective

Cancer is a life-threatening disease, and there is a significant need for novel technologies to treat cancer with an effective outcome and low toxicity. Photothermal therapy (PTT) is a noninvasive therapeutic tool that transports nanomaterials into tumors, absorbing light energy and converting it into heat, thus killing tumor cells. Gold nanorods (GNRs) have attracted widespread attention in recent years due to their unique optical and electronic properties and potential applications in biological imaging, molecular detection, and drug delivery, especially in the PTT of cancer and other diseases. This review summarizes the recent progress in the synthesis methods and surface functionalization of GNRs for PTT. The current major synthetic methods of GNRs and recently improved measures to reduce toxicity, increase yield, and control particle size and shape are first introduced, followed by various surface functionalization approaches to construct a controlled drug release system, increase cell uptake, and improve pharmacokinetics and tumor-targeting effect, thus enhancing the photothermal effect of killing the tumor. Finally, a brief outlook for the future development of GNRs modification and functionalization in PTT is proposed.

Application of Dendrimers for Treating Parasitic Diseases

Despite advances in medical knowledge, parasitic diseases remain a significant global health burden and their pharmacological treatment is often hampered by drug toxicity. Therefore, drug delivery systems may provide useful advantages when used in combination with conventional therapeutic compounds. Dendrimers are three-dimensional polymeric structures, characterized by a central core, branches and terminal functional groups. These nanostructures are known for their defined structure, great water solubility, biocompatibility and high encapsulation ability against a wide range of molecules. Furthermore, the high ratio between terminal groups and molecular volume render them a hopeful vector for drug delivery. These nanostructures offer several advantages compared to conventional drugs for the treatment of parasitic infection. Dendrimers deliver drugs to target sites with reduced dosage, solving side effects that occur with accepted marketed drugs. In recent years, extensive progress has been made towards the use of dendrimers for therapeutic, prophylactic and diagnostic purposes for the management of parasitic infections. The present review highlights the potential of several dendrimers in the management of parasitic diseases.

The Tumor Proteolytic Landscape: A Challenging Frontier in Cancer Diagnosis and Therapy

In recent decades, dysregulation of proteases and atypical proteolysis have become increasingly recognized as important hallmarks of cancer, driving community-wide efforts to explore the proteolytic landscape of oncologic disease. With more than 100 proteases currently associated with different aspects of cancer development and progression, there is a clear impetus to harness their potential in the context of oncology. Advances in the protease field have yielded technologies enabling sensitive protease detection in various settings, paving the way towards diagnostic profiling of disease-related protease activity patterns. Methods including activity-based probes and substrates, antibodies, and various nanosystems that generate reporter signals, i.e., for PET or MRI, after interaction with the target protease have shown potential for clinical translation. Nevertheless, these technologies are costly, not easily multiplexed, and require advanced imaging technologies. While the current clinical applications of protease-responsive technologies in oncologic settings are still limited, emerging technologies and protease sensors are poised to enable comprehensive exploration of the tumor proteolytic landscape as a diagnostic and therapeutic frontier. This review aims to give an overview of the most relevant classes of proteases as indicators for tumor diagnosis, current approaches to detect and monitor their activity in vivo, and associated therapeutic applications.

Internally Responsive Nanomaterials for Activatable Multimodal Imaging of Cancer

Advances in technology and nanomedicine have led to the development of nanoparticles that can be activated for multimodal imaging of cancer, where a stimulus induces a material modification that enhances image contrast. Multimodal imaging using nanomaterials with this capability can combine the advantages and overcome the limitations of any single imaging modality. When designed with stimuli-responsive abilities, the target-to-background ratio of multimodal imaging nanoprobes increases because specific stimuli in the tumor enhance the signal. Several aspects of the tumor microenvironment can be exploited as an internal stimulus response for multimodal imaging applications, such as the pH gradient, redox processes, overproduction of various enzymes, or combinations of these. In this review, design strategies are discussed and an overview of the recent developments of internally responsive multimodal nanomaterials is provided. Properly implementing this approach improves noninvasive cancer diagnosis and staging as well as provides a method to monitor drug delivery and treatment response.

Manganese-nitrogen and gadolinium-nitrogen Co-doped graphene quantum dots as bimodal magnetic resonance and fluorescence imaging nanoprobes

Graphene quantum dots (GQDs) are unique derivatives of graphene that show promise in multiple biomedical applications as biosensors, bioimaging agents, and drug/gene delivery vehicles. Their ease in functionalization, biocompatibility, and intrinsic fluorescence enable those modalities. However, GQDs lack deep tissue magnetic resonance imaging (MRI) capabilities desirable for diagnostics. Considering that the drawbacks of MRI contrast agent toxicity are still poorly addressed, we develop novel Mn²⁺ or Gd³⁺ doped nitrogen-containing graphene quantum dots (NGQDs) to equip the GQDs with MRI capabilities and at the same time render contrast agents biocompatible. Water-soluble biocompatible Mn-NGQDs and Gd-NGQDs synthesized via single-step microwave-assisted scalable hydrothermal reaction enable dual MRI and fluorescence modalities. These quasi-spherical 3.9-6.6 nm average-sized structures possess highly crystalline graphitic lattice structure with 0.24 and 0.53 atomic % for Mn²⁺ and Gd³⁺ doping. This structure ensures high in vitro biocompatibility of up to 1.3 mg ml^-1 and 1.5 mg ml^-1 for Mn-NGQDs and Gd-NGQDs, respectively, and effective internalization in HEK-293 cells traced by intrinsic NGQD fluorescence. As MRI contrast agents with considerably low Gd and Mn content, Mn-NGQDs exhibit substantial transverse/longitudinal relaxivity (r ₂/r ₁) ratios of 11.190, showing potential as dual-mode longitudinal or transverse relaxation time (T ₁ or T ₂) contrast agents, while Gd-NGQDs possess r ₂/r ₁ of 1.148 with high r ₁ of 9.546 mM^-1 s^-1 compared to commercial contrast agents, suggesting their potential as T1 contrast agents. Compared to other nanoplatforms, these novel Mn²⁺ and Gd³⁺ doped NGQDs not only provide scalable biocompatible alternatives as T1/T2 and T1 contrast agents but also enable in vitro intrinsic fluorescence imaging.