Level Of Cross-linking Research Articles

Effect of sodium bicarbonate on quality of machine-made Kongxin noodles

Kongxin (hollow) noodle is a traditional staple food in China and is well-known for its high eating quality. To meet the growing need of market, modern machine and fermentation technique have been applied to produce Kongxin noodles. In order to achieve high quality of food product, the effect of sodium bicarbonate (NaHCO3) ranging from 0 to 4 g/kg flour on quality of machine-made Kongxin noodles was investigated. The addition of NaHCO3 decreased the optimal cooking time of Kongxin noodles significantly (p < 0.05). Additionally, elasticity, firmness, chewiness of Kongxin noodles showed significant (p < 0.05) increasing trends. The improvement of NaHCO3 to quality of noodles may be because it promoted starch gelatinization and level of gluten cross-linking. However, the addition of NaHCO3 at 4 g/kg flour increased the cooking loss of Kongxin noodles significantly (p < 0.05), which might be because the gluten network formed by excessive crossing-linking limited the swelling of starch. Finally, the optimal cooking and textural qualities were observed at the level of 3 g/kg of NaHCO3. In conclusion, addition of NaHCO3 improved the quality of Kongxin noodles by promoting starch gelatinization and gluten cross-linking.

Chemical gradients in PIR foams as probed by ATR-FTIR analysis and consequences on fire resistance

Taking into account numerous results from the literature, an in-depth exploratory study on the chemical gradients in the rise (or depth) direction was performed on polyisocyanurate rigid (PIR) foam insulation panels using ATR-FTIR spectroscopy. In particular, it was found that the isocyanurate/phenyl ratio is a quick and effective technique for providing an indication of the level of trimer conversion within each sample. More importantly, a detailed analysis of the C–N stretching vibration of the isocyanurate ring as a function of depth revealed a linear decrease in the frequency peak maximum with the increase in the isocyanurate ratio for all investigated PIR foams. This result suggests for the first time that the position (frequency) of peak maximum (C–N stretching of isocyanurate ring) may be used to quantify the extent of isocyanurate formation without the issues linked to the use of absorbances. It is proposed that this reduction in the frequency of the C–N stretching vibration of isocyanurate ring reflects the decrease in hydrogen bonding between N–H of urethane group and CO within the isocyanurate ring when the isocyanurate content increases (lower mobility associated with higher level of cross-linking). The heterogeneity of the isocyanurate content was physically confirmed by investigating the flammability of the foam samples taken at different positions in the rise direction (z-axis).

Acid-Induced Gelation of Enzymatically and Nonenzymatically Cross-Linked Caseins-Texture Properties, and Microstructural Insights.

Casein gels consist of a fractal organized network of aggregated casein particles. The gel texture thereby depends on the structure, the spatial distribution, and the interaction forces of the network's elementary building blocks. The aim of this study was to explore the technofunctional consequences of a possible specificity of Maillard reaction-induced cross-linking reactions on casein with respect to texture and microstructure of acid gels. Therefore, sodium caseinate glycated with lactose in the dry state (60 °C, aw 0.5) was compared with casein samples cross-linked with methylglyoxal, with glutaraldehyde, or via microbial transglutaminase, respectively, at similar levels of protein cross-linking as confirmed by size-exclusion chromatography under denaturing conditions. Casein gels prepared by acidification with glucono-δ-lactone were characterized concerning pH kinetics during gelation, mechanical texture properties under large deformation, and water-holding capacity, while viscometric properties of casein suspensions were obtained prior to gelation. The gel microstructure was captured by confocal laser scanning microscopy and evaluated by means of image texture analysis. All protein cross-linking reactions studied led to an enhanced gel strength which was accompanied by an increased interconnectivity of the gel network and a decrease in apparent pore sizes. Gels with more densely packed strands, as was the case for enzymatically modified casein, exhibited pronounced mechanical stability. The spontaneous destabilization of the gel network upon prolonged glycation reactions, which was not obviously displayed by microstructural features but connected to an increased viscosity and pronounced pseudoplastic flow of the unacidified suspension, suggests a limitation of particle rearrangements and the weakening of interparticle protein-protein interactions by additional structure attributes formed during the early Maillard reaction (glycoconjugation).

Properties of extruded cross-linked waxy maize starches and their effects on extruded oat flour

The objectives of this study were to study the extrusion of cross-linked waxy maize starches (CLWMS) with different cross-linking levels and their function as a secondary ingredient in extruded oat flour (OF) formulations. CLWMS (18 %) and OF (82 %) were hydrated to 20 % moisture content and subjected to twin-screw extrusion at the screw speed of 350 rpm. Low cross-linking level of CLWMS (0.05 % sodium trimetaphosphate/sodium tripolyphosphate) in OF formulation increased the void fraction and reduced the breaking strength of extrudates. The low cross-linked starch was more resistant to breakdown and had a higher pasting viscosity than the unmodified starch. Higher cross-linking levels of CLWMS restricted swelling of starch granule and increased the resistant starch level of OF formulation but had very poor structural and textural properties. Varying the level of cross-linking offers an alternative way to manipulate the structural, textural and nutritional properties of extrudates in snack and cereal applications.

Reducing False Negatives in COVID-19 Testing by Using Microneedle-Based Oropharyngeal Swabs

Coronavirus disease 2019 (COVID-19) has become a severe threat to human health worldwide. Early etiological diagnosis plays a critical role in controlling COVID-19 pandemic. However, etiological diagnosis has been largely compromised by high “false-negative” rates of viral nucleic acid testing, resulting from limited sampling efficiency using conventional oropharyngeal swabs. Here, we engineer regular swabs by using a microneedle (MN) patch to significantly improve the quality and quantity of virus collection. The combination of MNs with different crosslinking levels endows the patches with dual capability of mucus penetration and virus extraction. Moreover, the antibody (Ab) against viral spike protein was integrated into the patch, conferring MNs with an active virus capture potential. By taking advantage of the biological and engineered species, we believe that the designed MN/Ab swabs could serve as a promising tool to improve current sampling efficiency with fewer false negatives, contributing to the containment of the COVID-19 pandemic.

Atomic insights into the sintering process of polycyclic aromatic hydrocarbon clusters

In this work, we studied the sintering process of two homogeneous polycyclic aromatic hydrocarbon (PAH) clusters with diameters in the range of 3–6 nm using molecular dynamics (MD) simulations. The sintering process was quantified through monitoring the solvent accessible surface area (SASA) and the distance between the center of mass (COM) of the two PAH clusters. The effect of temperature and crosslinking level of PAH clusters on sintering was investigated. The results show that the sintering rate of two PAH clusters at a certain temperature T is largely dependent on the melting point (TMP) of the PAH cluster. When T is higher than TMP, the characteristic sintering time (τs) is around 10−2 ns and sintering is not affected by the crosslinking level as the PAH clusters are liquid-like. In contrast, when T is much lower than TMP, the PAH clusters sinter rather slowly with τs > 5 ns, and the sintering process is hindered by the crosslinks between PAH molecules within solid-like PAH clusters due to the enhanced steric effect.

The functional significance of redox-mediated intersubunit cross-linking in regulation of human type 2 ryanodine receptor

The type 2 ryanodine receptor (RyR2) plays a key role in the cardiac intracellular calcium (Ca2+) regulation. We have previously shown that oxidative stress activates RyR2 in rabbit cardiomyocytes by promoting the formation of disulfide bonds between neighboring RyR2 subunits. However, the functional significance of this redox modification for human RyR2 (hRyR2) remains largely unknown. Here, we studied the redox regulation of hRyR2 in HEK293 cells transiently expressing the ryr2 gene. Analysis of hRyR2 cross-linking and of the redox-GFP readout response to diamide oxidation revealed that hRyR2 cysteines involved in the intersubunit cross-linking are highly sensitive to oxidative stress. In parallel experiments, the effect of diamide on endoplasmic reticulum (ER) Ca2+ release was studied in cells co-transfected with hRyR2, ER Ca2+ pump (SERCA2a) and the ER-targeted Ca2+ sensor R-CEPIA1er. Expression of hRyR2 and SERCA2a produced “cardiac-like” Ca2+ waves due to spontaneous hRyR2 activation. Incubation with diamide caused a fast decline of the luminal ER Ca2+ (or ER Ca2+ load) followed by the cessation of Ca2+ waves. The maximal effect of diamide on ER Ca2+ load and Ca2+ waves positively correlates with the maximum level of hRyR2 cross-linking, indicating a functional significance of this redox modification. Furthermore, the level of hRyR2 cross-linking positively correlates with the degree of calmodulin (CaM) dissociation from the hRyR2 complex. In skeletal muscle RyR (RyR1), cysteine 3635 (C3635) is viewed as dominantly responsible for the redox regulation of the channel. Here, we showed that the corresponding cysteine 3602 (C3602) in hRyR2 does not participate in intersubunit cross-linking and plays a limited role in the hRyR2 regulation by CaM during oxidative stress. Collectively, these results suggest that redox-mediated intersubunit cross-linking is an important regulator of hRyR2 function under pathological conditions associated with oxidative stress.

Cross-linking/sulfonation to improve paste stability, adhesion and film properties of corn starch for warp sizing

To investigate the influence of cross-linking/sulfonation on the viscosity stability, adhesion, film properties and desizability of corn starch for ameliorating its end-use ability in application of warp sizing, a series of itaconic acid cross-linked and sulfonated starch (IACLSS) samples with different levels of cross-linking (LCL) and degrees of substitution (DS) were synthesized by the cross-linking of acid-converted starch (ACS) with itaconic acid (IA) and subsequent sulfonation with NaHSO3. The apparent viscosity and viscosity stability were determined and adhesion was evaluated using a standardized method (FZ/T 15,001–2008). Film properties were also estimated in terms of tensile strength, breaking elongation, bending endurance, and moisture regain and the desizability of the IACLSS samples was investigated by measuring the time required to break the films in hot water. The experimental results showed that cross-linking/sulfonation was capable of improving the viscosity stability of cooked starch paste, enhancing the adhesion of starch to cotton and polyester fibers, increasing breaking elongation, bending endurance and moisture regain of starch film as well as decreasing its tensile strength, thereby stabilizing paste viscosity, ameliorating the adhesion to fibers and diminishing film brittleness. In addition, modification could reduce the time required to break the films in 80 °C water, indicating that modification favored the desizing of starch in hot water. Increasing sulfonation levels whilst decreasing the LCL values favored improvement in stability and desizability, enhancement in the adhesion to cotton and polyester fibers, and decrease in brittleness. The IACLSS showed potential in the applications of cotton and polyester sizing.

Morphological, functional and thermal characteristics of hydroxypropylated-crosslinked barley starches

The present study investigated effects of three different levels of crosslinking using a mixture of sodium trimetaphosphate (STMP) and sodium tripolyphosphate (STPP) on hydroxypropylated barley starches. Hydroxypropylated barley starches crosslinked with 1%, 1.5% and 2% mixture of STMP and STPP were coded as HPCL(1), HPCL(1.5) and HPCL(2.0), respectively. However, the level of hydroxypropylation employed was same for all the modifications i.e. 6%. The results showed that increase in level of crosslinking increased swelling power, solubility and water holding capacity of starches. HPCL(2.0) starch demonstrated noticeably lower percent transmittance, higher percent retrogradation and elevated peak viscosity. Harder gels were produced by dual modified barley starches. A decline was observed in thermal transition temperatures after dual modification. FTIR was unable to detect much difference among different samples. However, peak at 1414 cm−1 associated with hydroxypropylation was detected. Hydroxypropylation followed by crosslinking led to roughness and grooves formation on the surface of barley starch granules.

Characterization of crosslinked Macrotyloma uniflorum(Horsegram) protein films for packaging and medical applications

Natural polymers such as proteins and polysaccharides are of great demand in packaging and medical applications. Horse gram (Macrotyloma uniflorum) is a good source of protein and possess excellent antioxidant properties. The present study investigates the development and potential applications of transparent and water-resistant horse gram protein-based films crosslinked with citric acid. Films prepared were further characterized for their physical, chemical and biological properties. Films crosslinked at higher concentrations (15%) of citric acid exhibited 50% reduction in water sorption and reduced water vapor permeability. At 15% citric acid concentration, the films showed excellent free radical scavenging of up to 96%. Also, maximum antimicrobial activity against clinical isolates were observed for the 15% citric acid crosslinked films. Increase in thermal stability and decrease in water vapor permeability was obtained at higher levels of crosslinking. The crosslinked films were cytocompatible and showed potential to be used as substrates for cell culture. Citric acid crosslinked horse gram protein films have good physicochemical properties along with biological activities and could be suitable for applications in the packaging and medical fields.

Design of pH-responsive SAP polymer for pore solution chemistry regulation and crack sealing in cementitious materials

The crack development is considered to be one of the most severe threats to the durability of concrete infrastructure. This study aims to enhance the durability performance of cementitious material with the pH-responsive Superabsorbent Polymer (SAP). The SAP was synthesized with acrylic acid (AA)-methyl acrylate (MA) precursors, and three type samples with different crosslinking levels were prepared. The examination on the pH sensitivity indicated that the swelling capacity of the prepared SAP would first increase and then decrease with solution alkalinity, and the peak swelling potential was achieved around pH value of 12 for all the three type SAP with solution/gel mass ratio of 500. Further examination indicated the alkalinity of the buffer solution was reduced during the adsorption test, which can be caused by the hydrolysis of the amide groups and the crosslinker. Besides that, it was also found the solution/gel ratio and the Ca(OH)2 content could affect the swelling potential of the SAP. After that, the performance tests were conducted for the evaluation of concrete with SAP. A wax-coating protocol for the SAP was designed by using the hot-water method to prevent its swelling during mixing process. It was found that the strength reduction for samples with wax-coated SAP was insignificant compared to that of the control samples. Furthermore, durability tests supported the wax-shell could be broken by the crack propagation in concrete. And further experimental studies are needed to optimize the wax-size and shell thickness for enhanced self-sealing efficiency.

Recycling Waste Tires into Ground Tire Rubber (GTR)/Rubber Compounds: A Review

Recycling and recovery of waste tires is a serious environmental problem since vulcanized rubbers require several years to degrade naturally and remain for long periods of time in the environment. This is associated to a complex three dimensional (3D) crosslinked structure and the presence of a high number of different additives inside a tire formulation. Most end-of-life tires are discarded as waste in landfills taking space or incinerated for energy recovery, especially for highly degraded rubber wastes. All these options are no longer acceptable for the environment and circular economy. However, a great deal of progress has been made on the sustainability of waste tires via recycling as this material has high potential being a source of valuable raw materials. Extensive researches were performed on using these end-of-life tires as fillers in civil engineering applications (concrete and asphalt), as well as blending with polymeric matrices (thermoplastics, thermosets or virgin rubber). Several grinding technologies, such as ambient, wet or cryogenic processes, are widely used for downsizing waste tires and converting them into ground tire rubber (GTR) with a larger specific surface area. Here, a focus is made on the use of GTR as a partial replacement in virgin rubber compounds. The paper also presents a review of the possible physical and chemical surface treatments to improve the GTR adhesion and interaction with different matrices, including rubber regeneration processes such as thermomechanical, microwave, ultrasonic and thermochemical producing regenerated tire rubber (RTR). This review also includes a detailed discussion on the effect of GTR/RTR particle size, concentration and crosslinking level on the curing, rheological, mechanical, aging, thermal, dynamic mechanical and swelling properties of rubber compounds. Finally, a conclusion on the current situation is provided with openings for future works.

3D-Printed Strain-Gauge Micro Force Sensors

This paper presents the development of 3D-printed micro force sensors with micronewton sensing resolutions. Two representative 3D printing techniques, fused deposition method (FDM) and stereolithography (SLA), are utilized to establish polymeric micro sensor structures with a resolution down to 300 μm. Two types of 3D-printed strain-gauge force sensors have been designed aiming at different force measurement ranges (0-2.5 mN and 0-120 mN) with micronewton force sensing resolutions (4.3 <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">μ</sub> N and 56 <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">μ</sub> N, respectively). As a proof-of-concept demonstration, the two 3D-printed force sensors are used in custom-made mechanical characterization systems for measuring Young's moduli of polydimethylsiloxane (PDMS) samples at different crosslinking levels. The experimental technique presented here could empower rapid prototyping of high-performance force sensors utilizing consumer-level 3D printers, and will significantly boost the flexible design and customization of force-sensing systems with a variety of design requirements.

Age-related changes in the physical properties, cross-linking, and glycation of collagen from mouse tail tendon

Collagen is a structural protein whose internal cross-linking critically determines the properties and functions of connective tissue. Knowing how the cross-linking of collagen changes with age is key to understanding why the mechanical properties of tissues change over a lifetime. The current scientific consensus is that collagen cross-linking increases with age and that this increase leads to tendon stiffening. Here, we show that this view should be reconsidered. Using MS-based analyses, we demonstrated that during aging of healthy C57BL/6 mice, the overall levels of collagen cross-linking in tail tendon decreased with age. However, the levels of lysine glycation in collagen, which is not considered a cross-link, increased dramatically with age. We found that in 16-week-old diabetic db/db mice, glycation reaches levels similar to those observed in 98-week-old C57BL/6 mice, while the other cross-links typical of tendon collagen either decreased or remained the same as those observed in 20-week-old WT mice. These results, combined with findings from mechanical testing of tendons from these mice, indicate that overall collagen cross-linking in mouse tendon decreases with age. Our findings also reveal that lysine glycation appears to be an important factor that contributes to tendon stiffening with age and in diabetes.

Physical, mechanical and transport properties of emulsified films based on alginate with soybean oil: Effects of soybean oil concentration, number of passes and degree of surface crosslinking

Edible films and coatings have been applied on fruits to improve their quality during growth and development as well as during postharvest storage. A response surface methodology was used to determine the effects of oil concentration, number of passes and calcium chloride concentration on the physical, mechanical and transport properties of oil-alginate composite films. Alginate-based films were developed using alginate (1.0% w/v), soybean oil (0.5%, 1.0% and 1.5% v/v) and Tween 80® (1% v/v). Coarse emulsions were passed 2, 4 and 6 times through a microfluidizer at 200 MPa. Calcium chloride solutions (0%, 1.5% and 3%) were then applied on the cast films to crosslink them. The oil particle sizes ranged from 360 to 445 nm, regardless of the emulsion composition and number of passes. The lowest water permeability value (1.8857E-10 g/msPa) was obtained for 1.5% oil concentration, 6 passes and no crosslinking. The porosity of the films at low oil concentrations increased with an increase in crosslinking level. In comparison, the porosity of the films at high oil concentrations decreased with an increase in crosslinking level. Emulsified films showed reduced strength and increased elongation with an increase in oil concentration. Films treated with calcium chloride showed lower strength due to greater effects from oil than calcium chloride. In conclusion, oil incorporation in films was the predominant factor in improved film properties, especially for water vapor permeability.

LOCAL NANO-MECHANICAL PROPERTIES OF CROSS-LINKED POLYBUTYLENE

Cross-linking is a process in which polymer chains are associated through chemical bonds. The cross-linking level can be adjusted by the irradiation dosage and often by means of a cross-linking booster. The polymer additional cross-linking influences the surface nano and micro layers in the way comparable to metals during the thermal and chemical-thermal treatments. Polybutylene terephthalate (PBT) can be found in a group of structural polymers, which are often used in industry, especially in automotive. Applying the technology of electron radiation induces a creation of 3D network structure, which improves the local mechanical properties. These were later measured by a depth sensing indentation (DSI) test. This state of the art method is based on immediate detection of indentation depth in relation to applied force. The creation of 3D network caused an increase in nano-mechanical properties values, such as indentation hardness and indentation modulus, in comparison to the virgin material. The indentation hardness rose by 80%, while the indentation modulus elevated by 62%. The selected structural materials, e.g. PBT, were modified by the electron irradiation in a positive way and as such could be moved to a group of high performance materials.

Bio-based removable pressure-sensitive adhesives derived from carboxyl-terminated polyricinoleate and epoxidized soybean oil

A novel kind of fully bio-based PSAs were obtained through the curing reaction between two components derived from the plant oils: carboxyl-terminated polyricinoleate (PRA) from the castor oil and epoxidized soybean oil (ESO). The gel content, glass transition temperature (Tg), rheological behavior, tensile strength, creep resistance and 180° peel strength of the PSAs were feasibly tailored by adjusting the component ratio of ESO to PRA. At low cross-linking level, the PSAs behaved like a viscous liquid and did not possess enough cohesiveness to sustain the mechanical stress during peeling. The PSAs cross-linked at or near the optimal stoichiometric conditions displayed an adhesive (interfacial) failure between the substrate and the adhesive layer, which were associated with the lowest adhesion levels. The PSAs with the dosage amount of ESO ranging from 10∼20 wt% were tacky and flexible, which exhibited 180° peel strength ranging from 0.4∼2.3 N/cm; and could be easily removed without any residues on the adherend. The process for the preparation of the fully bio-based PSAs was environmentally friendly without using any organic solvent or other toxic chemical, herein showing the great potential as sustainable materials.

Effect of cross-linking and hydration on microscale flat punch indentation contact to collagen-hyaluronic acid films in the viscoelastic limit

The properties of the extracellular matrix (ECM) have profound impact upon cell behaviour. As an abundant protein in mammals, collagen is a desirable base material to engineer an ECM tissue scaffold, but its structural weakness generally requires molecular crosslinking or incorporation of additional ECM-based macromolecules such as glycosaminoglycans. We have performed microscopic indentation to test collagen films under dry and aqueous conditions prepared with different levels of physical and chemical crosslinking. Our technique isolates intrinsic properties of the poro-viscoelastic matrix in a regime minimizing the influence of drainage hydrodynamics and allows direct measurement of the effect of hydrating a specific sample. A doubling of the effective stress-strain stiffness under crosslinking could be directly correlated to structural changes in X-ray diffraction spectra, while electron microscopy revealed possible fibril bridging mechanisms explaining observed toughness. Overall, an intrinsic viscoelastic stress-strain response of collagen under various conditions of cross-linking was observed for both dry and wet conditions, with the latter most affected by indentation rate. Under creep testing, a three order of magnitude increase in dynamic compliance and factor three reduction in relaxation time was found going from the dry to hydrated state. When fitted to a simple viscoelastic model, crosslinking showed a tendency to decrease relaxation time in both states, but reduced dynamic compliance only in the hydrated case. This suggests a reduced role of virtual crosslinks under hydration. This is the first study reporting consistent mechanical testing of dry and hydrated ECM-derived biomaterials, accessing the intrinsic material mechanics under in vivo-like conditions. Statement of SignificanceThis manuscript presents new insights into the effect of crosslinking on mechanical properties of dry and hydrated collagen intended for tissue scaffolding applications. A novel microscopic indentation technique allowed testing of the poro-viscoelastic matrix isolated in a regime minimizing the influence of drainage hydrodynamics, so direct comparison of the effect of hydration on the intrinsic material behaviour to could be made. A variety of experimental techniques including X-ray diffraction, infrared spectroscopy, and scanning electron and atomic force microscopy were used to augment the mechanical testing. The results of creep testing were numerically analysed using a four-component viscoelastic model. This is the first mechanical testing of dry and hydrated ECM-derived biomaterials, accessing the intrinsic material mechanics under in vivo-like conditions.

Tuning of adhesion and disintegration of oxidized starch adhesives for the recycling of medium density fiberboard

Oxidized starch (OS) adhesives with a balance between their adhesion and disintegration properties were prepared by controlling the degree of oxidation and modifying the cross-linker type and level to replace urea-formaldehyde (UF) resins for easy recycling of medium density fiberboard (MDF). Four molar ratios of H2O2/starch, two types of cross-linker, i.e., blocked-pMDI (B-pMDI) and citric acid (CA), and three levels of the cross-linkers were employed to tailor the performance of the OS adhesives. The OS reacted with the isocyanate groups from the B-pMDI to form amide linkages, while it formed ester linkages by reacting with the CA. The resulting B-pMDI/OS-bonded MDF had better physical and mechanical properties than the CA/OS-bonded MDF, with comparable adhesion (0.34 MPa) to UF resins and ten times greater degree of fiber disintegration than UF resins. The combination of a 0.5 molar ratio OS with 7.5 wt% of B-pMDI produced MDF exhibiting an optimal balance between adhesion and disintegration, suggesting that such OS adhesives could someday replace UF resins in manufacturing and recycling of MDF without formaldehyde emission.

Generation of Aggregates of α-Lactalbumin by UV-B Light Exposure.

Whey proteins are widely used as ingredients in the form of aggregates to obtain certain functionalities in food applications. The aim of this study was to understand how UV illumination generates aggregates of α-lactalbumin (α-LA) as an alternative to heat treatments traditionally used for industrial production of protein aggregates. Absorption of UV light by α-LA caused cleavage of disulfide bonds and release of thiol groups, which resulted in primarily disulfide-mediated aggregation. This process mediated efficient aggregation with up to 98% monomer conversion into aggregates through formation of intermolecular disulfide bonds, while only minor levels of nonreducible cross-links were observed. SDS-PAGE analysis revealed that illumination led to formation of dimeric, trimeric, and oligomeric forms of α-LA. LC-MS/MS analysis showed that all of the four native disulfide bonds in α-LA were cleaved by UV illumination but to different extents, and the extent of cleavage was found to be higher in the absence of calcium. Seventeen different non-native disulfides were formed after 24 h of UV illumination. Two dityrosine bonds were identified (Tyr103-Tyr103 and Tyr36-Tyr103) alongside ditryptophan (Trp118-Trp118) and tyrosine-tryptophan (Tyr50-Trp60) cross-links. In addition, Trp60, Trp118, Cys73, Cys91, Cys120, Phe80, Met90, His68, and His107 were found to be oxidized up to 12% as compared to a nonilluminated control. Our work illustrates that light exposure can be used for generation of α-LA aggregates, but optimization of the illumination conditions is required to reduce oxidative damage to Trp, Cys, Phe, Met, and His residues.