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Open Access Publications from the University of California

Scholarly Works (11 results)

  • Thesis
  • Peer Reviewed
UC San Diego Electronic Theses and Dissertations (2023)

Advancements in nanomedicines have enabled breakthroughs in both disease diagnosis and treatment, including ultrasound bioimaging and cancer immunotherapy. On the one hand, nanomedicines of various formulations have been used as ultrasound contrast and greatly improved the ultrasound imaging quality. However, an ideal ultrasound contrast agent— that has tunable, modifiable surface, biodegradability, biocompatibility, and sufficient stability (half-life) for transient ultrasound imaging— is yet to be explored. On the other hand, to overcome the limitations of immune checkpoint blockage therapy,— immune-related toxicity and inefficacy in immune-suppressive tumors— nanomedicines have been rationally designed to trigger immunogenic cell death (ICD) of tumor cells. However, further work is necessary to develop ICD-inducing nanomedicines that are biodegradable, biocompatible, and intrinsically potent in inducing ICD. In this dissertation, I will discuss how creating novel nanomedicines can benefit both ultrasound imaging and cancer immunotherapy.First chapter reviews applications of nanomedicines in both ultrasound imaging and ICD-based cancer immunotherapy, with a highlight of successes and limitations of existing nanomedicines. Second chapter describes how sol-gel reaction combined with electrospray can generate biodegradable calcium phosphate micro/nano particles. Effects of synthetic parameters on the particle size and morphology are discussed in detail. The biodegradability of these particles was validated. Third chapter illustrates a bio-inspired, facile, mild, and solution-based synthetic method for creating calcium phosphate micro/nano particles. Systematic investigations on synthetic parameters led to calcium phosphate particles with versatile sizes (396±128 nm to 63±8 µm) and morphologies (hexagonal micro-disc, micro-flower, micro-leaf, nano-butterfly, and nano-ribbon). A “phosphate sponge” mechanism was found to be the key for regulating the particle sizes and morphologies. These calcium phosphate micro/nano particles are proven to be biodegradable, non-toxic, and efficient in creating transient ultrasound contrast. Fourth chapter studies the building of proton sponge nano-assembly (PSNA) optimized for imaging and triggering ICD of cancer cells. By carefully tuning the hydrophilic and hydrophobic components, the self-assembly tendency of PSNA was optimized. In turn, the PSNA with the highest fluorescence, positive surface charge density, intracellular fluorescence, and cancer cell cytotoxicity was achieved. The lysosome rupturing-regulated pyroptosis and necroptosis were triggered by PSNA, suggesting the great potential of the PSNA for anticancer immunity.

    • Article
    • Peer Reviewed
    UC San Diego Previously Published Works (2022)
    Synchronization is important for photoacoustic (PA) tomography, but some fixed delays between the data acquisition (DAQ) and the light pulse are a common problem degrading imaging quality. Here, we present a simple yet versatile method named Scissors to help synchronize ultrasound open platforms (UOPs) for PA imaging. Scissors is a programed function that can cut or add a fixed delay to radio frequency (RF) data and, thus, synchronize it before reconstruction. Scissors applies the programmable metric of UOPs and has several advantages. It is compatible with many setups regardless of the synchronization methods, light sources, transducers, and delays. The synchronization is adjustable in steps reciprocal to the UOPs sampling rate (20-ns step with a 50-MHz sampling rate). Scissors works in real-time PA imaging, and no extra hardware is needed. We programed Scissors in Vantage UOP (Verasonics, Inc., Kirkland, WA, USA) and then imaged two 30- [Formula: see text] nichrome wires with a 20.2-MHz central frequency transducer. The PA image was severely distorted by an 828-ns delay; over 90% delay was caused by our Q -switch laser. The axial and lateral resolutions are 112 and [Formula: see text], respectively, after using Scissors. We imaged a human finger in vivo, and the imaging quality is tremendously improved after solving the 828-ns delay by using Scissors.
      Cover page: Synchronization of RF Data in Ultrasound Open Platforms (UOPs) for High-Accuracy and High-Resolution Photoacoustic Tomography Using the Scissors Programming Method.
      • Article
      • Peer Reviewed
      UC San Diego Previously Published Works (2023)
      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.
        Cover page: Protease-Responsive Potential-Tunable AIEgens for Cell Selective Imaging of TMPRSS2 and Accurate Inhibitor Screening.
        • Article
        • Peer Reviewed
        UC San Diego Previously Published Works (2022)
        Heparin is a common anticoagulant, but heparin overdose is a common intensive care unit (ICU) medication error due to the narrow therapeutic window of heparin. Conventional methods to monitoring heparin suffer from long turnaround time, the need for skilled personnel, and low frequency of sampling. To overcome these issues, we describe here a fiber optic photoacoustic (PA) sensor for real-time heparin monitoring. The proposed sensor was validated with in vitro testing and in a simulated in vivo model using the following samples: (1) phosphate-buffered saline (PBS), (2) spiked human plasma, (3) spiked whole human blood, and (4) clinical samples from patients treated with heparin. Samples were validated by comparing the PA signal to the activated partial thromboplastin time (aPTT) as well as the activated clotting time (ACT). Importantly, the proposed sensor has a short turnaround time (3 min) and a limit of detection of 0.18 U/ml in whole human blood. The PA signal is linear with heparin dose and correlates with the aPTT value (Pearson's r = 0.99). The PA signal from 32 clinical samples collected from eight patients linearly correlated with ACT values (Pearson's r = 0.89, in vitro; Pearson's r = 0.93, simulated in vivo). The PA signal was also validated against the cumulative heparin dose (Pearson's r = 0.94, in vitro; Pearson's r = 0.96, simulated in vivo). This approach could have applications in both in vitro and real-time in vivo heparin monitoring.
          Cover page: A fiber optic photoacoustic sensor for real-time heparin monitoring
          • Article
          • Peer Reviewed
          UC San Diego Previously Published Works (2022)
          SIGNIFICANCE: Photoacoustic imaging has shown advantages over the periodontal probing method in measuring the periodontal probing depth, but the large size of conventional photoacoustic transducers prevents imaging of the more posterior teeth. AIM: Our aim is to develop a photoacoustic imaging system to image the more posterior periodontal pocket. APPROACH: We report a clinical hockey-stick-style transducer integrated with fibers for periodontal photoacoustic imaging. Cuttlefish ink labeled the periodontal pocket as the photoacoustic contrast agent. RESULTS: We characterized the imaging system and then measured the pocket depth of 35 swine teeth. Three raters evaluated the performance of the hockey-stick transducer. The measurements between the Williams probing (gold standard) and the photoacoustic methods were blinded but highly correlated. We showed a bias of ∼0.3  mm for the imaging-based technique versus Williams probing. The minimum inter-reliability was over 0.60 for three different raters of varying experience, suggesting that this approach to measure the periodontal pocket is reproducible. Finally, we imaged three pre-molars of a human subject. We could access more upper and posterior teeth than conventional linear transducers. CONCLUSIONS: The unique angle shape of the hockey-stick transducer allows it to image more posterior teeth than regular linear transducers. This study demonstrated the ability of a hockey-stick transducer to measure the periodontal pocket via photoacoustic imaging.
            Cover page: Photoacoustic imaging of posterior periodontal pocket using a commercial hockey-stick transducer.
            • Article
            • Peer Reviewed
            UC San Diego Previously Published Works (2024)
            Stability issues in membrane-free coacervates have been addressed with coating strategies, but these approaches often compromise the permeability of the coacervate. Here we report a facile approach to maintain both stability and permeability using tannic acid and then demonstrate the value of this approach in enzyme-triggered drug release. First, we develop size-tunable coacervates via self-assembly of heparin glycosaminoglycan with tyrosine and arginine-based peptides. A thrombin-recognition site within the peptide building block results in heparin release upon thrombin proteolysis. Notably, polyphenols are integrated within the nano-coacervates to improve stability in biofluids. Phenolic crosslinking at the liquid-liquid interface enables nano-coacervates to maintain exceptional structural integrity across various environments. We discover a pivotal polyphenol threshold for preserving enzymatic activity alongside enhanced stability. The disassembly rate of the nano-coacervates increases as a function of thrombin activity, thus preventing a coagulation cascade. This polyphenol-based approach not only improves stability but also opens the way for applications in biomedicine, protease sensing, and bio-responsive drug delivery.
              Cover page: Polyphenol-stabilized coacervates for enzyme-triggered drug delivery.
              • Article
              • Peer Reviewed
              UC San Diego Previously Published Works (2023)
              Electrostatic interactions are a key driving force that mediates colloidal assembly. The Schulze-Hardy rule states that nanoparticles have a higher tendency to coagulate in the presence of counterions with high charge valence. However, it is unclear how the Schulze-Hardy rule works when the simple electrolytes are replaced with more sophisticated charge carriers. Here, we designed cationic peptides of varying valencies and demonstrate that their charge screening behaviors on anionic gold nanoparticles (AuNPs) follow the six-power relationship in the Schulze-Hardy rule. This finding further inspires a simple yet effective strategy for measuring SARS-CoV-2 main protease (Mpro) via naked eyes. This work provides a unique avenue for fundamental NP disassembly based on the Schulze-Hardy rule and can help design versatile substrates for colorimetric sensing of other proteases.
                Cover page: Peptide valence-induced breaks in plasmonic coupling
                • Article
                • Peer Reviewed
                UC San Diego Previously Published Works (2022)
                Existing tools to detect and visualize severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) suffer from low selectivity, poor cell permeability, and high cytotoxicity. Here we report a novel self-immolative fluorescent probe (MP590) for the highly selective and sensitive detection of the SARS-CoV-2 main protease (Mpro). This fluorescent probe was prepared by connecting a Mpro-cleavable peptide (N-acetyl-Abu-Tle-Leu-Gln) with a fluorophore (i.e., resorufin) via a self-immolative aromatic linker. Fluorescent titration results show that MP590 can detect Mpro with a limit of detection (LoD) of 35 nM and is selective over interferents such as hemoglobin, bovine serum albumin (BSA), thrombin, amylase, SARS-CoV-2 papain-like protease (PLpro), and trypsin. The cell imaging data indicate that this probe can report Mpro in HEK 293T cells transfected with a Mpro expression plasmid as well as in TMPRSS2-VeroE6 cells infected with SARS-CoV-2. Our results suggest that MP590 can both measure and monitor Mpro activity and quantitatively evaluate Mpro inhibition in infected cells, making it an important tool for diagnostic and therapeutic research on SARS-CoV-2.
                  Cover page: A Self-Immolative Fluorescent Probe for Selective Detection of SARS-CoV‑2 Main Protease
                  • Article
                  • Peer Reviewed
                  UC San Diego Previously Published Works (2023)
                  Aromatic interactions are commonly involved in the assembly of naturally occurring building blocks, and these interactions can be replicated in an artificial setting to produce functional materials. Here we describe a colorimetric biosensor using co-assembly experiments with plasmonic gold and surfactant-like peptides (SLPs) spanning a wide range of aromatic residues, polar stretches, and interfacial affinities. The SLPs programmed in DDD-(ZZ)x -FFPC self-assemble into higher-order structures in response to a protease and subsequently modulate the colloidal dispersity of gold leading to a colorimetric readout. Results show the strong aggregation propensity of the FFPC tail without polar DDD head. The SLPs were specific to the target protease, i.e., Mpro , a biomarker for SARS-CoV-2. This system is a simple and visual tool that senses Mpro in phosphate buffer, exhaled breath condensate, and saliva with detection limits of 15.7, 20.8, and 26.1 nM, respectively. These results may have value in designing other protease testing methods.
                    Cover page: Peptide Amphiphile Mediated Co‐assembly for Nanoplasmonic Sensing
                    • Article
                    • Peer Reviewed
                    UC San Diego Previously Published Works (2022)
                    Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a serious threat to human health and lacks an effective treatment. There is an urgent need for both real-time tracking and precise treatment of the SARS-CoV-2-infected cells to mitigate and ultimately prevent viral transmission. However, selective triggering and tracking of the therapeutic process in the infected cells remains challenging. Here, we report a main protease (Mpro)-responsive, mitochondrial-targeting, and modular-peptide-conjugated probe (PSGMR) for selective imaging and inhibition of SARS-CoV-2-infected cells via enzyme-instructed self-assembly and aggregation-induced emission (AIE) effect. The amphiphilic PSGMR was constructed with tunable structure and responsive efficiency and validated with recombinant proteins, cells transfected with Mpro plasmid or infected by SARS-CoV-2, and a Mpro inhibitor. By rational construction of AIE luminogen (AIEgen) with modular peptides and Mpro, we verified that the cleavage of PSGMR yielded gradual aggregation with bright fluorescence and enhanced cytotoxicity to induce mitochondrial interference of the infected cells. This strategy may have value for selective detection and treatment of SARS-CoV-2-infected cells.
                      Cover page: Protease-Responsive Peptide-Conjugated Mitochondrial-Targeting AIEgens for Selective Imaging and Inhibition of SARS-CoV-2-Infected Cells.
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