We demonstrate a 968 nm diode end-pumped Er,Pr:GYSGG (Gd₁.₁₇Y₁.₈₃Sc₂Ga₃O₁₂) laser at 2.79 μm operated in the pulse and continuous-wave (CW) modes. The lifetimes for the upper laser level ⁴I₁₁/ ₂ and lower level ⁴I₁₃/₂ are 0.52 and 0.60 ms, respectively. The laser produces 284 mW of power in the CW mode, corresponding to the optical-to-optical efficiency of 14.8% and slope efficiency of 17.4%. The maximum laser energy achieved is 2.4 mJ at a repetition rate of 50 Hz and pulse duration of 0.5 ms, corresponding to a peak power of 4.8 W and slope efficiency of 18.3%. These results suggest that doping deactivator Pr3+ ions can effectively decrease the lower-level lifetime and improve the laser efficiency.

A series of vinylsulfonamides were synthesized and screened for site-selective modification of the ε-amino group of lysine-bearing free α-amine residues. N-Methyl-N-phenylethenesulfonamide has emerged as an applicable reagent and has been developed for efficient and highly selective modification of the lysine residue of native peptides in the presence of a free N-terminus via aza-Michael addition. We demonstrated that functional N-phenylvinylsulfonamide derivatives with a fluorescent moiety or drug could also be conjugated to the lysine residue of octreotide and insulin with high specificity, without modifying the N-terminus. Our method provides a promising strategy for site-selective lysine functionalization in native peptides with a free N-terminus.

We demonstrate a diode end-pumped Yb, Er, Ho:Gd(1.17)Y(1.83)Sc(2)Ga(3)O(12) (GYSGG) laser operated at 2.79 μm in continuous-wave mode. Spectral analysis shows that Yb(3+) and Ho(3+) act as sensitizer and deactivator ions, respectively. Pumping with a 967 nm laser diode produces the maximum output power of 411 mW, corresponding to optical-optical conversion and slope efficiencies of 11.6% and 13.1%, respectively. The minimum laser threshold is only 81 mW because of Ho(3+) doping. The laser properties are only slightly influenced by 100 mrad gamma irradiation. The Yb, Er, Ho:GYSGG crystal possesses excellent radiation resistance and is a potential laser gain medium in radiant environments.

A novel water soluble, phosphate-based enrichable, retro-Michael addition-driven MS-cleavable and multi-targeting cross-linker was developed.