Plastic nanoparticles cause proteome stress and aggregation by compromising cellular protein homeostasis ex vivo and in vivo.

Decomposition of plastic materials into minuscule particles and their long-term uptake pose increasing concerns on environmental sustainability and biosafety. Besides common cell viability and cytotoxicity evaluations, how plastic nanoparticles interfere with different stress response pathways and affect cellular fitness has been less explored. Here, we provided the first piece of evidence to demonstrate plastic nanoparticles potentially can deteriorate proteome stability, compromise cellular protein homeostasis, and consequently cause global proteome misfolding and aggregation. Polystyrene (PS) nanoparticles of different sizes and surface charges were exploited as model plastic materials. In cell lysate and human blood plasma, naked PS nanoparticles with hydrophobic surface deteriorated proteome thermodynamic stability and exaggerated its aggregation propensity. While no cell viability ablation was observed in cells treated with PS nanoparticles up to 200 µg·mL-1, global proteome aggregation and stress was detected by a selective proteome aggregation sensor. Further proteomics analysis revealed how protein homeostasis network was remodeled by positively charged PS nanoparticles via differential expression of key proteins to counteract proteome stress. In mice model, size-dependent liver accumulation of positively charged PS nanoparticles induced hepatocellular proteome aggregation and compromised protein homeostasis network capacity that were invisible to standard alanine transaminase and aspartate transaminase (ALT/AST) liver function as-say and histology. Meanwhile, long-term liver accumulation of plastic nanoparticles deteriorated liver metabolism and saturated liver detoxification capacity of overdosed acetaminophen. This work highlighted the impact of nanoplastics on cellular proteome integrity and cellular fitness that are invisible to current biochemical assays and clinical tests.

Solvatochromic Cellular Stress Sensors Reveal the Compactness Heterogeneity and Dynamics of Aggregated Proteome.

Deterioration of protein homeostasis (proteostasis) often induces aberrant proteome aggregation. Visualization and dissection of the stressed proteome are of particular interest given their association with numerous degenerative diseases. Recent progress in chemical cellular stress sensors allows for direct visualization of aggregated proteome. Beyond its localization and morphology, the physicochemical nature and the dynamics of the aggregated proteome have been challenging to explore. Herein, we developed a series of solvatochromic fluorene-based D-π-A probes that can selectively and noncovalently bind to a misfolded and aggregated proteome and report on their compactness heterogeneity upon cellular stresses. We achieved this goal by variation of the heterocyclic acceptors to modulate their solvatochromism and binding affinity to amorphous aggregated proteins. The optimized sensor P6 was capable of sensing the polarity differences among different aggregated proteins via its fluorescence emission wavelength. In live cells, P6 revealed the cellular compactness heterogeneity in the aggregated proteome upon cellular stresses. Given the combinative solvatochromic and noncovalent properties, our probe can reversibly monitor the dynamic changes in the aggregated proteome compactness upon stress and after stress recovery, suggesting its potential applications in search of therapeutics to counteract disease-causing proteome stresses.

Derivatizing Nile Red fluorophores to quantify the heterogeneous polarity upon protein aggregation in the cell.

Protein aggregation in the cell is often manifested by the formation of subcellular punctate structures. Herein, we modulated the solvatochromism and solubility of Nile Red fluorophore derivatives to quantitatively study the polarity inside pathogenic protein aggregates, revealing structure- and protein-dependent polarity heterogeneity.

Dynamic calibration and compensation method of a large-scale laser beam based on specular reflection for a nonorthogonal shaft laser theodolite measurement system.

The nonorthogonal shaft laser theodolite (N-theodolite) measurement system is a new kind of instrument that can be applied to large-scale metrology. Different from traditional theodolites, the three axes of the N-theodolite have no requirements on the orthogonality and intersection. For the measurement in laser scale, the parameters of the system on a large scale must be known. A calibration method of the laser beam based on specular reflection and its compensation are proposed, which are at a range of 12 m. Through the experiments, the results show that the straightness accuracy of the laser beam of the left N-theodolite is 0.12 mm at a range of 12 m, and the right one is 0.14 mm. Through the measurement experiments, the maximum measurement deviation of the system is 0.27 mm, which is verified to be a feasible method to calibrate the laser beam in large-scale space.

Dynamic calibration method of the laser beam for a non-orthogonal shaft laser theodolite measurement system.

The non-orthogonal shaft laser theodolite (N-theodolite) measurement system is a new kind of instrument applied to large-scale metrology. The system consists of two identical N-theodolites, each of which is made up of a two-dimensional rotary table and one collimated laser. The three axes of the N-theodolite have no strict requirements on their orthogonality and intersection conditions. A novel method, to the best of our knowledge, is proposed to calibrate the N-theodolite measurement system, and the calibration method of the laser beam for N-theodolite is the key innovation aspect of this paper. The laser beam is calibrated through dynamic rotation. Throughout the experiment, the straightness accuracy of the laser beam of the left N-theodolite is 0.08 mm and the right N-theodolite is 0.074 mm. The repeatability of the straightness accuracy is ${\pm 0.032}\,\,{\rm mm}$±0.032mm. The uncertainty of straightness accuracy is 0.040 mm. The measurement experiment results show that the maximum deviation of the measured value of this system is 0.34 mm at a range of 5 m, which is verified to be a feasible method for the calibration of the laser beam.