Is it acceptable to use a transport trolley for material transfer from one cleanliness class to another?

No. Transport trolleys are generally used as means of transport within the respective GMP cleanliness grade. Travelling from clean room class D to clean room class C for example is not permitted. Here, the material must be transferred from class D to a trolley only used in class C, in compliance with the corresponding SOP which describes the measures such as cleaning, disinfection, etc. The same applies to higher cleanliness classes.

[GMP Compliance Adviser, Chapter 3.M.3]