Search Results (455)

Nanoparticles offer a versatile platform for the selective eradication of pathogenic or diseased cells by integrating therapeutic payload delivery with precision targeting. Precision targeting can be achieved (1) actively through ligand conjugation, (2) passively by exploiting the physiological abnormalities of diseased tissues, or (3) intrinsically through the innate biophysical properties of the nanoparticle. Intrinsically selective nanoplatforms (iNPs) are particularly advantageous when the disease-promoting agent does not possess distinct surface markers, such as in the case of certain “untargetable cancers” or cancers without known targets. Indeed, nanocarriers for chemotherapeutic or gene delivery have achieved selective cancer cell apoptosis without requiring marker presentation, thereby expanding the therapeutic window of the payload. Disease-promoting agents whose physical properties are different from those of healthy cells are also good candidates for intrinsic nanoparticle targeting. For example, antimicrobial nanomaterials have been designed to disrupt bacterial membranes and reduce the risk of antimicrobial resistance by leveraging stiffness differentials between bacterial cell walls and eukaryotic membranes. Nanoparticle systems with intrinsic targeting mechanisms can also enable non-invasive imaging with near-infrared fluorescence, MRI, and photoacoustic imaging for real-time biodistribution tracking and treatment monitoring. This review synthesizes current innovations in nanoplatform design with intrinsic targeting capabilities, spans applications in infectious and non-communicable diseases, and discusses emerging strategies to enhance specificity, overcome resistance, and translate these platforms toward clinical and field deployment. Full article

Objectives: To systematically map the existing literature on ultrasound-based techniques for non-invasive visualization of the dermal microvasculature and identify methodological strengths, limitations, and evidence gaps. Methods: This scoping review was conducted according to PRISMA-ScR guidelines and registered on the Open Science Framework (DOI: 10.17605/OSF.IO/7VDUK). MEDLINE, PubMed, Embase, Scopus, and Web of Science were searched (January 2000–October 2025). Studies involving human participants and ultrasound-based techniques explicitly aimed at visualizing dermal microvasculature were included. Data on study design, population characteristics, imaging parameters, and reported outcomes were extracted and synthesized narratively. Results: Thirty-six studies published between 2007 and 2025 were included. Most were small feasibility or experimental studies (n = 24), with a median sample size of three participants and substantial heterogeneity in imaging protocols. Photoacoustic-based techniques were most frequently reported (n = 21) and were the most consistently described as providing high microvascular detail and functional assessment capability. High-frequency ultrasound (n = 10) and advanced Doppler methods (n = 7) also enabled visualization of dermal vessels, but showed variability in sensitivity, reporting, and standardization. Validation against histopathology was reported in only one study. Conclusions: Ultrasound-based techniques can visualize dermal microvasculature in vivo; however, evidence remains fragmented, methodologically heterogeneous, and largely derived from small exploratory studies. Standardized imaging protocols, pathology-based clinical cohorts and robust validation studies are required to establish comparative performance and enable clinical translation in radiology. Full article

Background: Eyelid malignancies require accurate intraoperative margin control to achieve complete tumor excision while preserving the functional and aesthetic integrity of the periocular region. Mohs micrographic surgery (MMS) is widely regarded as the reference standard for margin-controlled excision, whereas frozen section–controlled excision (FSC) represents a reliable and widely used alternative in oculoplastic practice. In parallel, several emerging imaging technologies are being investigated to improve real-time tumor detection and surgical precision. Methods: A narrative review of the literature was conducted to summarize current evidence on intraoperative margin control in eyelid tumor surgery. The review focused on established surgical techniques, including MMS and FSC, as well as emerging imaging modalities such as fluorescence confocal microscopy, reflectance confocal microscopy, optical coherence tomography, line-field confocal optical coherence tomography, photoacoustic imaging, and artificial intelligence (AI)-assisted analysis. Results: MMS provides complete circumferential peripheral and deep margin assessment and remains the benchmark for high-risk, recurrent, and poorly defined periocular tumors, particularly basal cell carcinoma. FSC offers favorable oncologic outcomes, allows immediate reconstruction, and remains an effective option when MMS is not available. Emerging imaging modalities have shown promising diagnostic performance for tumor detection, presurgical mapping, and intraoperative support, particularly in basal cell carcinoma, although evidence in periocular tumors remains limited for most techniques. AI-assisted approaches have also demonstrated high accuracy in the interpretation of frozen sections and optical imaging data, suggesting potential to improve workflow efficiency and diagnostic consistency. Conclusions: MMS and FSC remain the current standards for intraoperative margin control in eyelid tumor surgery. Emerging imaging technologies and AI-based tools may further enhance surgical precision and tissue preservation, but most remain investigational in the periocular setting. Further prospective studies are needed to validate their clinical utility, define standardized workflows, and clarify their role alongside established histopathologic techniques. Full article

Photoacoustic imaging (PAI) is an emerging hybrid biomedical imaging modality that combines the high molecular contrast of optical excitation with the deep tissue penetration of ultrasound detection. This review presents recent advances in PAI-based techniques for the detection and characterization of gynecological diseases in women, with particular focus on endometriosis and uterine-related disorders. We summarize the application of PAI across preclinical and translational studies, highlighting progress in photoacoustic microscopy, spectroscopic photoacoustic imaging, and endoscopic and probe-based implementations for non-invasive, high-resolution tissue evaluation. The role of functional and contrast-enhanced PAI approaches is discussed, emphasizing their ability to enhance diagnostic sensitivity, enable longitudinal monitoring, and provide detailed information on vascular, biochemical, and structural tissue characteristics. Furthermore, the expanding applications of PAI in assessing uterine, cervical, and ovarian pathologies, including tumor detection and tissue remodeling, are reviewed. Finally, current challenges, limitations, and future directions toward clinical translation are addressed. Collectively, this review underscores the potential of photoacoustic imaging as a powerful, non-invasive platform for early diagnosis, disease monitoring, and improved management of women’s health conditions. Full article

Capacitive micromachined ultrasonic transducers (CMUTs) have been developed over the past 30 years and achieved practical applications in both medical imaging and industrial non-destructive testing. This article presents the fundamental principles of CMUTs and surveys fabrication technologies, offering a comprehensive review of major advances and challenges in medical ultrasound and photoacoustic imaging applications. The article further reviews and analyzes three primary challenges currently confronting CMUTs in medical imaging applications: lower output acoustic pressure, dielectric charging effects, and the need for high bias voltage. It also presents and discusses a potential combined approach to comprehensively address these challenges, with the aim of enhancing CMUT performance and broadening clinical adoption. Full article

The design of novel aggregation-induced emission (AIE)-active molecules represents a cutting-edge strategy for integrated phototheranostics in the second near-infrared (NIR-II) window. This review systematically outlines rational molecular engineering approaches based on D-A, D-A-D, and A-D-A systems to achieve red-shifted NIR-II absorption/emission, enhanced AIE characteristics, and balanced radiative and non-radiative decay pathways. These AIEgens enable high-contrast NIR-II fluorescence imaging (FLI) and photoacoustic imaging (PAI) for precise tumor localization, while concurrently facilitating efficient photothermal therapy (PTT) and robust photodynamic therapy (PDT) through both type-I and type-II mechanisms. Nanoformulations of these molecules exhibit excellent stability, biocompatibility, and passive targeting via the enhanced permeability and retention (EPR) effect. We further highlight representative “all-in-one” AIE platforms that demonstrate synergistic PTT/PDT under multimodal imaging guidance, offering a promising paradigm for precision cancer theranostics. Challenges and future directions in clinical translation and combination therapy are also discussed. Full article

Glioblastoma (GBM) remains the most aggressive primary malignant brain tumor in adults, with poor survival largely driven by diffuse cellular infiltration, profound heterogeneity, and near-universal recurrence following standard therapy. Although maximizing the extent of resection is a key determinant of patient outcome, current clinical imaging modalities lack the spatial resolution necessary to detect microscopic tumor invasion and therapy-resistant cell populations. Emerging in vivo imaging technologies capable of cellular and near-single-cell resolution have therefore become a major focus in preclinical neuro-oncology research, with growing relevance for surgical guidance, treatment adaptation, and translational discovery. This review evaluates multiple optical imaging modalities, including multi-photon microscopy, near-infrared II fluorescence imaging, bioluminescence imaging, photoacoustic imaging, optical coherence tomography, confocal laser endomicroscopy, Raman spectroscopy, autofluorescence microscopy, and fluorescence macroscopy with a focus on their ability to detect residual GBM cells. Despite significant advances, these approaches remain constrained by limitations in molecular target availability, probe delivery across the blood–brain barrier, and signal variability within heterogeneous tumor regions. The biological complexity of GBM further challenges detection, as residual tumor cells are spatially dispersed and phenotypically diverse, limiting the effectiveness of single-marker or single-modality strategies. Together, these findings highlight the need for integrated, biologically informed imaging approaches to improve detection of residual disease and guide surgical decision making. Full article

Recently, photoacoustic (PA) imaging has made a significant impact on biomedical imaging, providing detailed information on tissue structure and function by integrating optical and acoustic techniques. PA imaging can provide functional information at the cellular (e.g., oxygen saturation, hemoglobin concentration, metabolic rate) and molecular levels, owing to its substantial advantages over conventional imaging techniques. PA imaging is particularly useful for neuroimaging, cancer detection, and cardiovascular studies. Over the last decade, there has been a tremendous amount of research and development dedicated to nanomaterials that are ideal for PA imaging. Examples of nanomaterials include carbon-based and gold nanorods, both of which demonstrate greatly enhanced light absorption capabilities in the near-infrared range. Therefore, the properties of these materials make them perfect for achieving deep penetration into tissues. In addition, they exhibit biocompatibility, tunable optical properties, and enhance the acoustic signal for PA imaging, resulting in greater accuracy and precision in PA results. Researchers working in this area have focused on developing nanomaterials with fabrication capabilities, enabling real-time visualization of therapeutic events and enhancing light absorption. This review critically examines recent advances in nanomaterials for PA imaging, emphasizing strategies for signal enhancement and evaluating their impact on imaging performance, including imaging depth, photostability, and signal intensity, as well as their suitability for biomedical applications. Furthermore, complementary approaches for PA signal enhancement are discussed to provide a broader perspective and guide the selection and design of effective contrast agents for clinical and preclinical use. Full article

Light-based diagnostic and therapeutic approaches are increasingly important in modern biomedicine, with organic dyes emerging as versatile optical agents due to their tunable photophysical properties. Precise control over absorption and emission characteristics has enabled their application in fluorescence, photoacoustic, and Raman imaging, as well as in photodynamic and photothermal therapies. However, challenges related to biocompatibility, aqueous stability, and in vivo performance remain critical for clinical translation. Organic dyes that absorb in the near-infrared region are particularly attractive because of their deeper tissue penetration and reduced background interference. This review highlights key structure property relationships of organic dyes and summarizes current design strategies, including chromophore modification, peripheral functionalization for water solubility, and self-assembled nanotheranostic systems. Recent biomedical applications in cancer diagnosis and therapy, bacterial detection, and imaging-guided treatment are discussed, along with future directions for advancing dye-based technologies in healthcare. Full article

A robust and cost-effective fiber-optic ultrasound sensor based on a slope-symmetric Fabry–Perot interferometer (FPI) is presented, employing dual-channel quadrature-biased heterodyne interrogation with an acousto-optic modulator (AOM). By introducing a 200 MHz frequency shift that yields an effective π/2 phase offset between the direct (unshifted) and frequency-shifted optical paths, the system ensures complementary sensitivity: when one channel operates at zero slope on the FPI transfer function (minimum sensitivity), the other resides at maximum slope, providing inherent immunity to laser wavelength drift and environmental perturbations. Experimental validation demonstrates reliable ultrasound detection across varying operating points. At quadrature extremes, one channel achieves peak amplitudes of ±2 V while the other is quiescent, whereas intermediate points enable simultaneous detection with amplitudes of ±1.5 V (AOM channel) and ±0.05–0.1 V (direct channel), accompanied by corresponding DC levels ranging from ~0.4 V to 1.6 V. The AOM channel utilizes simple envelope detection after 9.5–11.5 MHz bandpass filtering, maintaining low cost, though coherent mixing is suggested for enhanced weak-signal performance. The angle-symmetric FPI design, combined with gold-disk reflector adaptations and potential femtosecond laser micromachining, further reduces fabrication costs without sacrificing finesse or sensitivity. This quadrature-biased approach offers superior stability compared to single-channel systems, making it highly suitable for practical applications in photoacoustic imaging, nondestructive testing, and structural health monitoring. Full article

The engineering of theranostic nanoparticles, which integrate diagnostics and therapy in a single administration, enables targeted drug delivery and disease visualization. In cancer theranostics, gadolinium-based nanoparticles are valuable tools for noninvasive magnetic resonance imaging (MRI) and provide high-resolution images of the tumor. When MRI is combined with other imaging modalities, complementary therapeutic information is obtained for more accurate identification of tumor characteristics and precise guidance of anticancer drug delivery. Among the many possible modalities combined with MRI, photoacoustic imaging (PAI) is a candidate that enables sensitive in vivo detection of tumors. We have already succeeded in synthesizing biocompatible gelatin-coated gadolinium oxide nanoparticles with a controlled size by adjusting the timing of gelatin addition, which were a highly efficient contrast agent for MR and PA dual imaging. Herein, we conjugated a clinically used anticancer drug (doxorubicin, DOX) to size-defined and biocompatible gadolinium oxide nanoparticles which are novel theranostic probes. Succinylated gelatin enabled the electrostatic conjugation of DOX with gadolinium oxide nanoparticles, and the release of DOX was controlled through the enzymatic degradation of gelatin by matrix metalloproteinases-2 and -9 (MMP-2 and MMP-9), which are highly expressed in cancer cells. The released DOX efficiently inhibited the growth of HeLa cells in vitro and the growth of the inoculated tumor tissues in vivo. The dual-modality MRI and PAI capabilities provide anatomical information that assists in the localization and targeting of theranostic probes. Full article

Circular-Scan photoacoustic tomography (PAT) can provide high-resolution images of optical absorption, but its analytical reconstructions, such as delay-and-sum (DAS), are highly sensitive to scanning radius (SR) inaccuracies, which cause severe geometric distortions and artifacts. In this work, we propose a deep learning framework, termed smooth deconvolution ResNet (SD-ResNet), to correct DAS reconstruction degradation induced by SR errors. SD-ResNet uses an ImageNet-pretrained ResNet-50 encoder and a lightweight deconvolutional decoder with additional smoothing convolutions to suppress checkerboard artifacts and restore fine structural details. A paired training dataset is generated using k-Wave simulations driven by human thoracic computed tomography (CT) slices: for each phantom, radiofrequency data are simulated once, and DAS images reconstructed with the true SR serve as ground truth, whereas images reconstructed with biased SR values serve as inputs. This design provides structurally diverse training samples and enhances generalization. In silico experiments show that SD-ResNet effectively recovers image quality across a range of SR deviations. Phantom experiments with polyethylene microspheres further confirm that the proposed method can substantially reduce artifacts and recover correct source shapes under practical SR mismatches, offering a robust tool for SR-error-resilient PAT imaging. Full article

Background/Objectives: Autologous fat grafting (AFG) is widely used in breast reconstruction; however, graft retention remains unpredictable due to recipient-bed variability. Photoacoustic imaging (PAI) is a contrast-free, noninvasive modality enabling visualization of vascular structures in detail. This study used PAI to visualize and quantitatively assess neovascularization and vascular structure in breasts reconstructed with AFG. Methods: In this retrospective, cross-sectional study, data from eight patients who underwent PAI of both reconstructed and contralateral breasts at least three months after their final AFG procedure for total breast reconstruction were used. Excluding the nipple–areola complex and skin markings, four 3 × 3 cm regions of interest (one per quadrant) were selected in the periareolar region. Vascular density in terms of depth from the skin surface was analyzed in five cases with adequate contact between the device and the skin. Visible vessel diameters within the regions of interest were manually measured and categorized as small, medium, or large to assess distribution patterns. Results: PAI successfully enabled visualization of vascular structures on the reconstructed side in all cases, even at depths greater than 10 mm. In five cases, vascular density in the superficial layer (0–2.5 mm) was higher on the reconstructed side than on the contralateral side. A longer postoperative interval was associated with a higher proportion of small vessels and fewer large vessels. Conclusions: PAI enabled noninvasive visualization of vascular structures consistent with neovascularization on the reconstructed side after AFG. Temporal changes in vessel diameter distribution suggest ongoing vascular remodeling, supporting the potential utility of PAI in assessing vascular structural changes in grafted tissue over time. Full article

The tumor microenvironment, characterized by higher acidity, hypoxia, and dense cellular structures, plays a pivotal role in cancer progression, therapeutic resistance, and treatment response. Nanoparticle-based contrast agents enable the precise delineation of solid regions within heterogeneous tumors through advanced molecular imaging techniques. Since 1956, ultrasound (US) medical imaging has provided essential anatomical and functional insights about internal organs. More recently, magnetomotive ultrasound (MMUS) has emerged as a promising imaging modality, using a modulated magnetic field to exert force on superparamagnetic iron oxide nanoparticles (SPIONs), inducing motion in the surrounding tissues through mechanical coupling. In parallel, magnetic hyperthermia (MH), which employs localized heating by alternating magnetic fields, has demonstrated significant potential in selectively destroying cancer cells while sparing healthy tissues. This review summarizes the current state of IONP-based contrast agents, with particular emphasis on their use in MH for cancer treatment, as well as their potential in multimodal imaging, including MMUS, and photoacoustic (PA) imaging. The advantages and limitations of IONPs in tumor detection and characterization are discussed, examining the development of surface-functionalized MNPs, and analyzing how material properties and environmental factors affect their diagnostic and therapeutical performance. Finally, strategies for combining MMUS and PA modalities for pre-clinical cancer imaging are proposed. Full article

Recent advancements in nanotechnology have led to the development of multifunctional nanoplatforms that significantly enhance both cancer diagnosis and treatment. Gold-based nanoparticles, such as peptide-functionalized nanostructures and PEG-coated nanorods, offer improved tumor targeting, multimodal imaging (including photoacoustic and fluorescence), and effective photothermal therapy. Similarly, ultrafine iron oxide nanoprobes provide superior tumor imaging, while silver-based nanoparticles exhibit rapid systemic circulation, near-infrared fluorescence, and powerful photothermal properties. Titanium-based nanoplatforms enable a combination of therapies and advanced imaging methods. On the therapeutic side, polymeric nanoparticles (PNPs), silica-based platforms, PEG-based nanoparticles, and graphene oxide-based systems each offer unique advantages for targeted drug delivery and theranostics. PNPs, with tunable size, shape, and surface chemistry, enable controlled drug release and reduced side effects, while silica-based nanoplatforms improve tumor targeting and imaging. PEG-based nanoparticles enhance drug release and tumor penetration, and graphene oxide-based systems facilitate subcellular targeting and synergistic therapies. Collectively, these innovations are paving the way for more efficient, precise, and safer cancer therapies, leading to improved clinical outcomes. Full article